[PATCH v1] hw/pci-host: save/restore pci host config register

Wang King posted 1 patch 3 years, 9 months ago
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git fetch https://github.com/patchew-project/qemu tags/patchew/20200723125303.2390-1-king.wang@huawei.com
Maintainers: "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
There is a newer version of this series
hw/pci-host/i440fx.c       | 11 +++++++++++
hw/pci-host/q35.c          | 11 +++++++++++
hw/pci/pci_host.c          | 11 +++++++++++
hw/pci/pcie_host.c         | 11 +++++++++++
include/hw/pci/pci_host.h  | 10 ++++++++++
include/hw/pci/pcie_host.h | 10 ++++++++++
6 files changed, 64 insertions(+)
[PATCH v1] hw/pci-host: save/restore pci host config register
Posted by Wang King 3 years, 9 months ago
From: Hogan Wang <king.wang@huawei.com>

The pci host config register is used to save PCI address for
read/write config data. If guest write a value to config register,
and then pause the vcpu to migrate, After the migration, the guest
continue to write pci config data, and the write data will be ignored
because of new qemu process lost the config register state.

Reproduction steps are:
1. guest booting in seabios.
2. guest enable the SMRAM in seabios:piix4_apmc_smm_setup, and then
   expect to disable the SMRAM by pci_config_writeb.
3. after guest write the pci host config register, and then pasued vcpu
   to finish migration.
4. guest write config data(0x0A) fail to disable the SMRAM becasue of
   config register state lost.
5. guest continue to boot and crash in ipxe option ROM due to SMRAM in
   enabled state.

Signed-off-by: Hogan Wang <king.wang@huawei.com>

---
 hw/pci-host/i440fx.c       | 11 +++++++++++
 hw/pci-host/q35.c          | 11 +++++++++++
 hw/pci/pci_host.c          | 11 +++++++++++
 hw/pci/pcie_host.c         | 11 +++++++++++
 include/hw/pci/pci_host.h  | 10 ++++++++++
 include/hw/pci/pcie_host.h | 10 ++++++++++
 6 files changed, 64 insertions(+)

diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c
index 8ed2417f0c..17705bb025 100644
--- a/hw/pci-host/i440fx.c
+++ b/hw/pci-host/i440fx.c
@@ -118,6 +118,16 @@ static const VMStateDescription vmstate_i440fx = {
     }
 };
 
+static const VMStateDescription vmstate_i440fx_pcihost = {
+    .name = "I440FX_PCIHost",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_PCI_HOST(parent_obj, I440FXState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static void i440fx_pcihost_get_pci_hole_start(Object *obj, Visitor *v,
                                               const char *name, void *opaque,
                                               Error **errp)
@@ -398,6 +408,7 @@ static void i440fx_pcihost_class_init(ObjectClass *klass, void *data)
     hc->root_bus_path = i440fx_pcihost_root_bus_path;
     dc->realize = i440fx_pcihost_realize;
     dc->fw_name = "pci";
+    dc->vmsd = &vmstate_i440fx_pcihost;
     device_class_set_props(dc, i440fx_props);
     /* Reason: needs to be wired up by pc_init1 */
     dc->user_creatable = false;
diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index b67cb9c29f..5e323be2e3 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -165,6 +165,16 @@ static void q35_host_get_pci_hole64_end(Object *obj, Visitor *v,
     visit_type_uint64(v, name, &value, errp);
 }
 
+static const VMStateDescription vmstate_q35_pcihost = {
+    .name = "Q35_PCIHost",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_PCIE_HOST(parent_obj, Q35PCIHost),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 /*
  * NOTE: setting defaults for the mch.* fields in this table
  * doesn't work, because mch is a separate QOM object that is
@@ -194,6 +204,7 @@ static void q35_host_class_init(ObjectClass *klass, void *data)
 
     hc->root_bus_path = q35_host_root_bus_path;
     dc->realize = q35_host_realize;
+    dc->vmsd = &vmstate_q35_pcihost;
     device_class_set_props(dc, q35_host_props);
     /* Reason: needs to be wired up by pc_q35_init */
     dc->user_creatable = false;
diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
index ce7bcdb1d5..7cdd5a3ea3 100644
--- a/hw/pci/pci_host.c
+++ b/hw/pci/pci_host.c
@@ -24,6 +24,7 @@
 #include "hw/pci/pci_host.h"
 #include "qemu/module.h"
 #include "hw/pci/pci_bus.h"
+#include "migration/vmstate.h"
 #include "trace.h"
 
 /* debug PCI */
@@ -200,6 +201,16 @@ const MemoryRegionOps pci_host_data_be_ops = {
     .endianness = DEVICE_BIG_ENDIAN,
 };
 
+const VMStateDescription vmstate_pcihost = {
+    .name = "PCIHost",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(config_reg, PCIHostState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const TypeInfo pci_host_type_info = {
     .name = TYPE_PCI_HOST_BRIDGE,
     .parent = TYPE_SYS_BUS_DEVICE,
diff --git a/hw/pci/pcie_host.c b/hw/pci/pcie_host.c
index 3534006f99..a653c39bb7 100644
--- a/hw/pci/pcie_host.c
+++ b/hw/pci/pcie_host.c
@@ -24,6 +24,7 @@
 #include "hw/pci/pcie_host.h"
 #include "qemu/module.h"
 #include "exec/address-spaces.h"
+#include "migration/vmstate.h"
 
 /* a helper function to get a PCIDevice for a given mmconfig address */
 static inline PCIDevice *pcie_dev_find_by_mmcfg_addr(PCIBus *s,
@@ -121,6 +122,16 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
     memory_region_transaction_commit();
 }
 
+const VMStateDescription vmstate_pciehost = {
+    .name = "PCIEHost",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_PCI_HOST(pci, PCIExpressHost),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const TypeInfo pcie_host_type_info = {
     .name = TYPE_PCIE_HOST_BRIDGE,
     .parent = TYPE_PCI_HOST_BRIDGE,
diff --git a/include/hw/pci/pci_host.h b/include/hw/pci/pci_host.h
index 9ce088bd13..fc88305e04 100644
--- a/include/hw/pci/pci_host.h
+++ b/include/hw/pci/pci_host.h
@@ -70,4 +70,14 @@ extern const MemoryRegionOps pci_host_conf_be_ops;
 extern const MemoryRegionOps pci_host_data_le_ops;
 extern const MemoryRegionOps pci_host_data_be_ops;
 
+extern const VMStateDescription vmstate_pcihost;
+
+#define VMSTATE_PCI_HOST(_field, _state) {                           \
+    .name       = (stringify(_field)),                               \
+    .size       = sizeof(PCIHostState),                              \
+    .vmsd       = &vmstate_pcihost,                                  \
+    .flags      = VMS_STRUCT,                                        \
+    .offset     = vmstate_offset_value(_state, _field, PCIHostState),\
+}
+
 #endif /* PCI_HOST_H */
diff --git a/include/hw/pci/pcie_host.h b/include/hw/pci/pcie_host.h
index 3f7b9886d1..e8856f03e9 100644
--- a/include/hw/pci/pcie_host.h
+++ b/include/hw/pci/pcie_host.h
@@ -78,4 +78,14 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
                                          PCIE_MMCFG_DEVFN_MASK)
 #define PCIE_MMCFG_CONFOFFSET(addr)     ((addr) & PCIE_MMCFG_CONFOFFSET_MASK)
 
+extern const VMStateDescription vmstate_pciehost;
+
+#define VMSTATE_PCIE_HOST(_field, _state) {                            \
+    .name       = (stringify(_field)),                                 \
+    .size       = sizeof(PCIExpressHost),                              \
+    .vmsd       = &vmstate_pciehost,                                   \
+    .flags      = VMS_STRUCT,                                          \
+    .offset     = vmstate_offset_value(_state, _field, PCIExpressHost),\
+}
+
 #endif /* PCIE_HOST_H */
-- 
2.23.0



Re: [PATCH v1] hw/pci-host: save/restore pci host config register
Posted by Michael S. Tsirkin 3 years, 9 months ago
On Thu, Jul 23, 2020 at 08:53:03PM +0800, Wang King wrote:
> From: Hogan Wang <king.wang@huawei.com>
> 
> The pci host config register is used to save PCI address for
> read/write config data. If guest write a value to config register,
> and then pause the vcpu to migrate, After the migration, the guest
> continue to write pci config data, and the write data will be ignored
> because of new qemu process lost the config register state.
> 
> Reproduction steps are:
> 1. guest booting in seabios.
> 2. guest enable the SMRAM in seabios:piix4_apmc_smm_setup, and then
>    expect to disable the SMRAM by pci_config_writeb.
> 3. after guest write the pci host config register, and then pasued vcpu
>    to finish migration.
> 4. guest write config data(0x0A) fail to disable the SMRAM becasue of
>    config register state lost.
> 5. guest continue to boot and crash in ipxe option ROM due to SMRAM in
>    enabled state.
> 
> Signed-off-by: Hogan Wang <king.wang@huawei.com>

I guess this is like v3 right?

thanks a lot for the patch!

My question stands : does anyone see a way to pass this
info around without breaking migration for all existing
machine types?


> ---
>  hw/pci-host/i440fx.c       | 11 +++++++++++
>  hw/pci-host/q35.c          | 11 +++++++++++
>  hw/pci/pci_host.c          | 11 +++++++++++
>  hw/pci/pcie_host.c         | 11 +++++++++++
>  include/hw/pci/pci_host.h  | 10 ++++++++++
>  include/hw/pci/pcie_host.h | 10 ++++++++++
>  6 files changed, 64 insertions(+)
> 
> diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c
> index 8ed2417f0c..17705bb025 100644
> --- a/hw/pci-host/i440fx.c
> +++ b/hw/pci-host/i440fx.c
> @@ -118,6 +118,16 @@ static const VMStateDescription vmstate_i440fx = {
>      }
>  };
>  
> +static const VMStateDescription vmstate_i440fx_pcihost = {
> +    .name = "I440FX_PCIHost",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_PCI_HOST(parent_obj, I440FXState),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
>  static void i440fx_pcihost_get_pci_hole_start(Object *obj, Visitor *v,
>                                                const char *name, void *opaque,
>                                                Error **errp)
> @@ -398,6 +408,7 @@ static void i440fx_pcihost_class_init(ObjectClass *klass, void *data)
>      hc->root_bus_path = i440fx_pcihost_root_bus_path;
>      dc->realize = i440fx_pcihost_realize;
>      dc->fw_name = "pci";
> +    dc->vmsd = &vmstate_i440fx_pcihost;
>      device_class_set_props(dc, i440fx_props);
>      /* Reason: needs to be wired up by pc_init1 */
>      dc->user_creatable = false;
> diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
> index b67cb9c29f..5e323be2e3 100644
> --- a/hw/pci-host/q35.c
> +++ b/hw/pci-host/q35.c
> @@ -165,6 +165,16 @@ static void q35_host_get_pci_hole64_end(Object *obj, Visitor *v,
>      visit_type_uint64(v, name, &value, errp);
>  }
>  
> +static const VMStateDescription vmstate_q35_pcihost = {
> +    .name = "Q35_PCIHost",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_PCIE_HOST(parent_obj, Q35PCIHost),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
>  /*
>   * NOTE: setting defaults for the mch.* fields in this table
>   * doesn't work, because mch is a separate QOM object that is
> @@ -194,6 +204,7 @@ static void q35_host_class_init(ObjectClass *klass, void *data)
>  
>      hc->root_bus_path = q35_host_root_bus_path;
>      dc->realize = q35_host_realize;
> +    dc->vmsd = &vmstate_q35_pcihost;
>      device_class_set_props(dc, q35_host_props);
>      /* Reason: needs to be wired up by pc_q35_init */
>      dc->user_creatable = false;
> diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
> index ce7bcdb1d5..7cdd5a3ea3 100644
> --- a/hw/pci/pci_host.c
> +++ b/hw/pci/pci_host.c
> @@ -24,6 +24,7 @@
>  #include "hw/pci/pci_host.h"
>  #include "qemu/module.h"
>  #include "hw/pci/pci_bus.h"
> +#include "migration/vmstate.h"
>  #include "trace.h"
>  
>  /* debug PCI */
> @@ -200,6 +201,16 @@ const MemoryRegionOps pci_host_data_be_ops = {
>      .endianness = DEVICE_BIG_ENDIAN,
>  };
>  
> +const VMStateDescription vmstate_pcihost = {
> +    .name = "PCIHost",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_UINT32(config_reg, PCIHostState),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
>  static const TypeInfo pci_host_type_info = {
>      .name = TYPE_PCI_HOST_BRIDGE,
>      .parent = TYPE_SYS_BUS_DEVICE,
> diff --git a/hw/pci/pcie_host.c b/hw/pci/pcie_host.c
> index 3534006f99..a653c39bb7 100644
> --- a/hw/pci/pcie_host.c
> +++ b/hw/pci/pcie_host.c
> @@ -24,6 +24,7 @@
>  #include "hw/pci/pcie_host.h"
>  #include "qemu/module.h"
>  #include "exec/address-spaces.h"
> +#include "migration/vmstate.h"
>  
>  /* a helper function to get a PCIDevice for a given mmconfig address */
>  static inline PCIDevice *pcie_dev_find_by_mmcfg_addr(PCIBus *s,
> @@ -121,6 +122,16 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
>      memory_region_transaction_commit();
>  }
>  
> +const VMStateDescription vmstate_pciehost = {
> +    .name = "PCIEHost",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_PCI_HOST(pci, PCIExpressHost),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
>  static const TypeInfo pcie_host_type_info = {
>      .name = TYPE_PCIE_HOST_BRIDGE,
>      .parent = TYPE_PCI_HOST_BRIDGE,
> diff --git a/include/hw/pci/pci_host.h b/include/hw/pci/pci_host.h
> index 9ce088bd13..fc88305e04 100644
> --- a/include/hw/pci/pci_host.h
> +++ b/include/hw/pci/pci_host.h
> @@ -70,4 +70,14 @@ extern const MemoryRegionOps pci_host_conf_be_ops;
>  extern const MemoryRegionOps pci_host_data_le_ops;
>  extern const MemoryRegionOps pci_host_data_be_ops;
>  
> +extern const VMStateDescription vmstate_pcihost;
> +
> +#define VMSTATE_PCI_HOST(_field, _state) {                           \
> +    .name       = (stringify(_field)),                               \
> +    .size       = sizeof(PCIHostState),                              \
> +    .vmsd       = &vmstate_pcihost,                                  \
> +    .flags      = VMS_STRUCT,                                        \
> +    .offset     = vmstate_offset_value(_state, _field, PCIHostState),\
> +}
> +
>  #endif /* PCI_HOST_H */
> diff --git a/include/hw/pci/pcie_host.h b/include/hw/pci/pcie_host.h
> index 3f7b9886d1..e8856f03e9 100644
> --- a/include/hw/pci/pcie_host.h
> +++ b/include/hw/pci/pcie_host.h
> @@ -78,4 +78,14 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
>                                           PCIE_MMCFG_DEVFN_MASK)
>  #define PCIE_MMCFG_CONFOFFSET(addr)     ((addr) & PCIE_MMCFG_CONFOFFSET_MASK)
>  
> +extern const VMStateDescription vmstate_pciehost;
> +
> +#define VMSTATE_PCIE_HOST(_field, _state) {                            \
> +    .name       = (stringify(_field)),                                 \
> +    .size       = sizeof(PCIExpressHost),                              \
> +    .vmsd       = &vmstate_pciehost,                                   \
> +    .flags      = VMS_STRUCT,                                          \
> +    .offset     = vmstate_offset_value(_state, _field, PCIExpressHost),\
> +}
> +
>  #endif /* PCIE_HOST_H */
> -- 
> 2.23.0
> 


Re: [PATCH v1] hw/pci-host: save/restore pci host config register
Posted by Dr. David Alan Gilbert 3 years, 9 months ago
* Michael S. Tsirkin (mst@redhat.com) wrote:
> On Thu, Jul 23, 2020 at 08:53:03PM +0800, Wang King wrote:
> > From: Hogan Wang <king.wang@huawei.com>
> > 
> > The pci host config register is used to save PCI address for
> > read/write config data. If guest write a value to config register,
> > and then pause the vcpu to migrate, After the migration, the guest
> > continue to write pci config data, and the write data will be ignored
> > because of new qemu process lost the config register state.
> > 
> > Reproduction steps are:
> > 1. guest booting in seabios.
> > 2. guest enable the SMRAM in seabios:piix4_apmc_smm_setup, and then
> >    expect to disable the SMRAM by pci_config_writeb.
> > 3. after guest write the pci host config register, and then pasued vcpu
> >    to finish migration.
> > 4. guest write config data(0x0A) fail to disable the SMRAM becasue of
> >    config register state lost.
> > 5. guest continue to boot and crash in ipxe option ROM due to SMRAM in
> >    enabled state.
> > 
> > Signed-off-by: Hogan Wang <king.wang@huawei.com>
> 
> I guess this is like v3 right?
> 
> thanks a lot for the patch!
> 
> My question stands : does anyone see a way to pass this
> info around without breaking migration for all existing
> machine types?

You need a .needed clause in the vmstate_i440fx_pcihost and
vmstate_q35_pcihost which is a pointer to a function which enables it on
new machine types and ignores it on old ones.

Or, if it always crashes if the SMRAM is enabled, then the migration is
dead anyway; so you could make the .needed only save the config if
the SMRAM is opened, so you'd get a unknown section error, which is
nasty but it would only happen in the case it would crash anyway.

Dave

> 
> > ---
> >  hw/pci-host/i440fx.c       | 11 +++++++++++
> >  hw/pci-host/q35.c          | 11 +++++++++++
> >  hw/pci/pci_host.c          | 11 +++++++++++
> >  hw/pci/pcie_host.c         | 11 +++++++++++
> >  include/hw/pci/pci_host.h  | 10 ++++++++++
> >  include/hw/pci/pcie_host.h | 10 ++++++++++
> >  6 files changed, 64 insertions(+)
> > 
> > diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c
> > index 8ed2417f0c..17705bb025 100644
> > --- a/hw/pci-host/i440fx.c
> > +++ b/hw/pci-host/i440fx.c
> > @@ -118,6 +118,16 @@ static const VMStateDescription vmstate_i440fx = {
> >      }
> >  };
> >  
> > +static const VMStateDescription vmstate_i440fx_pcihost = {
> > +    .name = "I440FX_PCIHost",
> > +    .version_id = 1,
> > +    .minimum_version_id = 1,
> > +    .fields = (VMStateField[]) {
> > +        VMSTATE_PCI_HOST(parent_obj, I440FXState),
> > +        VMSTATE_END_OF_LIST()
> > +    }
> > +};
> > +
> >  static void i440fx_pcihost_get_pci_hole_start(Object *obj, Visitor *v,
> >                                                const char *name, void *opaque,
> >                                                Error **errp)
> > @@ -398,6 +408,7 @@ static void i440fx_pcihost_class_init(ObjectClass *klass, void *data)
> >      hc->root_bus_path = i440fx_pcihost_root_bus_path;
> >      dc->realize = i440fx_pcihost_realize;
> >      dc->fw_name = "pci";
> > +    dc->vmsd = &vmstate_i440fx_pcihost;
> >      device_class_set_props(dc, i440fx_props);
> >      /* Reason: needs to be wired up by pc_init1 */
> >      dc->user_creatable = false;
> > diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
> > index b67cb9c29f..5e323be2e3 100644
> > --- a/hw/pci-host/q35.c
> > +++ b/hw/pci-host/q35.c
> > @@ -165,6 +165,16 @@ static void q35_host_get_pci_hole64_end(Object *obj, Visitor *v,
> >      visit_type_uint64(v, name, &value, errp);
> >  }
> >  
> > +static const VMStateDescription vmstate_q35_pcihost = {
> > +    .name = "Q35_PCIHost",
> > +    .version_id = 1,
> > +    .minimum_version_id = 1,
> > +    .fields = (VMStateField[]) {
> > +        VMSTATE_PCIE_HOST(parent_obj, Q35PCIHost),
> > +        VMSTATE_END_OF_LIST()
> > +    }
> > +};
> > +
> >  /*
> >   * NOTE: setting defaults for the mch.* fields in this table
> >   * doesn't work, because mch is a separate QOM object that is
> > @@ -194,6 +204,7 @@ static void q35_host_class_init(ObjectClass *klass, void *data)
> >  
> >      hc->root_bus_path = q35_host_root_bus_path;
> >      dc->realize = q35_host_realize;
> > +    dc->vmsd = &vmstate_q35_pcihost;
> >      device_class_set_props(dc, q35_host_props);
> >      /* Reason: needs to be wired up by pc_q35_init */
> >      dc->user_creatable = false;
> > diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
> > index ce7bcdb1d5..7cdd5a3ea3 100644
> > --- a/hw/pci/pci_host.c
> > +++ b/hw/pci/pci_host.c
> > @@ -24,6 +24,7 @@
> >  #include "hw/pci/pci_host.h"
> >  #include "qemu/module.h"
> >  #include "hw/pci/pci_bus.h"
> > +#include "migration/vmstate.h"
> >  #include "trace.h"
> >  
> >  /* debug PCI */
> > @@ -200,6 +201,16 @@ const MemoryRegionOps pci_host_data_be_ops = {
> >      .endianness = DEVICE_BIG_ENDIAN,
> >  };
> >  
> > +const VMStateDescription vmstate_pcihost = {
> > +    .name = "PCIHost",
> > +    .version_id = 1,
> > +    .minimum_version_id = 1,
> > +    .fields = (VMStateField[]) {
> > +        VMSTATE_UINT32(config_reg, PCIHostState),
> > +        VMSTATE_END_OF_LIST()
> > +    }
> > +};
> > +
> >  static const TypeInfo pci_host_type_info = {
> >      .name = TYPE_PCI_HOST_BRIDGE,
> >      .parent = TYPE_SYS_BUS_DEVICE,
> > diff --git a/hw/pci/pcie_host.c b/hw/pci/pcie_host.c
> > index 3534006f99..a653c39bb7 100644
> > --- a/hw/pci/pcie_host.c
> > +++ b/hw/pci/pcie_host.c
> > @@ -24,6 +24,7 @@
> >  #include "hw/pci/pcie_host.h"
> >  #include "qemu/module.h"
> >  #include "exec/address-spaces.h"
> > +#include "migration/vmstate.h"
> >  
> >  /* a helper function to get a PCIDevice for a given mmconfig address */
> >  static inline PCIDevice *pcie_dev_find_by_mmcfg_addr(PCIBus *s,
> > @@ -121,6 +122,16 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
> >      memory_region_transaction_commit();
> >  }
> >  
> > +const VMStateDescription vmstate_pciehost = {
> > +    .name = "PCIEHost",
> > +    .version_id = 1,
> > +    .minimum_version_id = 1,
> > +    .fields = (VMStateField[]) {
> > +        VMSTATE_PCI_HOST(pci, PCIExpressHost),
> > +        VMSTATE_END_OF_LIST()
> > +    }
> > +};
> > +
> >  static const TypeInfo pcie_host_type_info = {
> >      .name = TYPE_PCIE_HOST_BRIDGE,
> >      .parent = TYPE_PCI_HOST_BRIDGE,
> > diff --git a/include/hw/pci/pci_host.h b/include/hw/pci/pci_host.h
> > index 9ce088bd13..fc88305e04 100644
> > --- a/include/hw/pci/pci_host.h
> > +++ b/include/hw/pci/pci_host.h
> > @@ -70,4 +70,14 @@ extern const MemoryRegionOps pci_host_conf_be_ops;
> >  extern const MemoryRegionOps pci_host_data_le_ops;
> >  extern const MemoryRegionOps pci_host_data_be_ops;
> >  
> > +extern const VMStateDescription vmstate_pcihost;
> > +
> > +#define VMSTATE_PCI_HOST(_field, _state) {                           \
> > +    .name       = (stringify(_field)),                               \
> > +    .size       = sizeof(PCIHostState),                              \
> > +    .vmsd       = &vmstate_pcihost,                                  \
> > +    .flags      = VMS_STRUCT,                                        \
> > +    .offset     = vmstate_offset_value(_state, _field, PCIHostState),\
> > +}
> > +
> >  #endif /* PCI_HOST_H */
> > diff --git a/include/hw/pci/pcie_host.h b/include/hw/pci/pcie_host.h
> > index 3f7b9886d1..e8856f03e9 100644
> > --- a/include/hw/pci/pcie_host.h
> > +++ b/include/hw/pci/pcie_host.h
> > @@ -78,4 +78,14 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
> >                                           PCIE_MMCFG_DEVFN_MASK)
> >  #define PCIE_MMCFG_CONFOFFSET(addr)     ((addr) & PCIE_MMCFG_CONFOFFSET_MASK)
> >  
> > +extern const VMStateDescription vmstate_pciehost;
> > +
> > +#define VMSTATE_PCIE_HOST(_field, _state) {                            \
> > +    .name       = (stringify(_field)),                                 \
> > +    .size       = sizeof(PCIExpressHost),                              \
> > +    .vmsd       = &vmstate_pciehost,                                   \
> > +    .flags      = VMS_STRUCT,                                          \
> > +    .offset     = vmstate_offset_value(_state, _field, PCIExpressHost),\
> > +}
> > +
> >  #endif /* PCIE_HOST_H */
> > -- 
> > 2.23.0
> > 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK


答复: [PATCH v1] hw/pci-host: save/restore pci host config register
Posted by Wangjing (Hogan, Cloud Infrastructure Service Product Dept.) 3 years, 9 months ago
Wang King wrote:
> * Michael S. Tsirkin (mst@redhat.com) wrote:
> > On Thu, Jul 23, 2020 at 08:53:03PM +0800, Wang King wrote:
> > > From: Hogan Wang <king.wang@huawei.com>
> > > 
> > > The pci host config register is used to save PCI address for 
> > > read/write config data. If guest write a value to config register, 
> > > and then pause the vcpu to migrate, After the migration, the guest 
> > > continue to write pci config data, and the write data will be 
> > > ignored because of new qemu process lost the config register state.
> > > 
> > > Reproduction steps are:
> > > 1. guest booting in seabios.
> > > 2. guest enable the SMRAM in seabios:piix4_apmc_smm_setup, and then
> > >    expect to disable the SMRAM by pci_config_writeb.
> > > 3. after guest write the pci host config register, and then pasued vcpu
> > >    to finish migration.
> > > 4. guest write config data(0x0A) fail to disable the SMRAM becasue of
> > >    config register state lost.
> > > 5. guest continue to boot and crash in ipxe option ROM due to SMRAM in
> > >    enabled state.
> > > 
> > > Signed-off-by: Hogan Wang <king.wang@huawei.com>
> > 
> > I guess this is like v3 right?
> > 
> > thanks a lot for the patch!
> > 
> > My question stands : does anyone see a way to pass this info around 
> > without breaking migration for all existing machine types?
> 
> You need a .needed clause in the vmstate_i440fx_pcihost and vmstate_q35_pcihost which is a pointer to a function which enables it on new machine types and ignores it on old ones.
> 
> Or, if it always crashes if the SMRAM is enabled, then the migration is dead anyway; so you could make the .needed only save the config if the SMRAM is opened, so you'd get a unknown section error, which is nasty but it would only happen in the case it would crash anyway.
> 
> Dave
> 

It always crashes if the SMRAM is enabled, but it's just one case, config register
state lost may cause other uncertain errors, so it's need on new machine types.

> > 
> > > ---
> > >  hw/pci-host/i440fx.c       | 11 +++++++++++
> > >  hw/pci-host/q35.c          | 11 +++++++++++
> > >  hw/pci/pci_host.c          | 11 +++++++++++
> > >  hw/pci/pcie_host.c         | 11 +++++++++++
> > >  include/hw/pci/pci_host.h  | 10 ++++++++++  
> > > include/hw/pci/pcie_host.h | 10 ++++++++++
> > >  6 files changed, 64 insertions(+)
> > > 
> > > diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c index 
> > > 8ed2417f0c..17705bb025 100644
> > > --- a/hw/pci-host/i440fx.c
> > > +++ b/hw/pci-host/i440fx.c
> > > @@ -118,6 +118,16 @@ static const VMStateDescription vmstate_i440fx = {
> > >      }
> > >  };
> > >  
> > > +static const VMStateDescription vmstate_i440fx_pcihost = {
> > > +    .name = "I440FX_PCIHost",
> > > +    .version_id = 1,
> > > +    .minimum_version_id = 1,
> > > +    .fields = (VMStateField[]) {
> > > +        VMSTATE_PCI_HOST(parent_obj, I440FXState),
> > > +        VMSTATE_END_OF_LIST()
> > > +    }
> > > +};
> > > +
> > >  static void i440fx_pcihost_get_pci_hole_start(Object *obj, Visitor *v,
> > >                                                const char *name, void *opaque,
> > >                                                Error **errp) @@ 
> > > -398,6 +408,7 @@ static void i440fx_pcihost_class_init(ObjectClass *klass, void *data)
> > >      hc->root_bus_path = i440fx_pcihost_root_bus_path;
> > >      dc->realize = i440fx_pcihost_realize;
> > >      dc->fw_name = "pci";
> > > +    dc->vmsd = &vmstate_i440fx_pcihost;
> > >      device_class_set_props(dc, i440fx_props);
> > >      /* Reason: needs to be wired up by pc_init1 */
> > >      dc->user_creatable = false;
> > > diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c index 
> > > b67cb9c29f..5e323be2e3 100644
> > > --- a/hw/pci-host/q35.c
> > > +++ b/hw/pci-host/q35.c
> > > @@ -165,6 +165,16 @@ static void q35_host_get_pci_hole64_end(Object *obj, Visitor *v,
> > >      visit_type_uint64(v, name, &value, errp);  }
> > >  
> > > +static const VMStateDescription vmstate_q35_pcihost = {
> > > +    .name = "Q35_PCIHost",
> > > +    .version_id = 1,
> > > +    .minimum_version_id = 1,
> > > +    .fields = (VMStateField[]) {
> > > +        VMSTATE_PCIE_HOST(parent_obj, Q35PCIHost),
> > > +        VMSTATE_END_OF_LIST()
> > > +    }
> > > +};
> > > +
> > >  /*
> > >   * NOTE: setting defaults for the mch.* fields in this table
> > >   * doesn't work, because mch is a separate QOM object that is @@ 
> > > -194,6 +204,7 @@ static void q35_host_class_init(ObjectClass *klass, 
> > > void *data)
> > >  
> > >      hc->root_bus_path = q35_host_root_bus_path;
> > >      dc->realize = q35_host_realize;
> > > +    dc->vmsd = &vmstate_q35_pcihost;
> > >      device_class_set_props(dc, q35_host_props);
> > >      /* Reason: needs to be wired up by pc_q35_init */
> > >      dc->user_creatable = false;
> > > diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c index 
> > > ce7bcdb1d5..7cdd5a3ea3 100644
> > > --- a/hw/pci/pci_host.c
> > > +++ b/hw/pci/pci_host.c
> > > @@ -24,6 +24,7 @@
> > >  #include "hw/pci/pci_host.h"
> > >  #include "qemu/module.h"
> > >  #include "hw/pci/pci_bus.h"
> > > +#include "migration/vmstate.h"
> > >  #include "trace.h"
> > >  
> > >  /* debug PCI */
> > > @@ -200,6 +201,16 @@ const MemoryRegionOps pci_host_data_be_ops = {
> > >      .endianness = DEVICE_BIG_ENDIAN,  };
> > >  
> > > +const VMStateDescription vmstate_pcihost = {
> > > +    .name = "PCIHost",
> > > +    .version_id = 1,
> > > +    .minimum_version_id = 1,
> > > +    .fields = (VMStateField[]) {
> > > +        VMSTATE_UINT32(config_reg, PCIHostState),
> > > +        VMSTATE_END_OF_LIST()
> > > +    }
> > > +};
> > > +
> > >  static const TypeInfo pci_host_type_info = {
> > >      .name = TYPE_PCI_HOST_BRIDGE,
> > >      .parent = TYPE_SYS_BUS_DEVICE,
> > > diff --git a/hw/pci/pcie_host.c b/hw/pci/pcie_host.c index 
> > > 3534006f99..a653c39bb7 100644
> > > --- a/hw/pci/pcie_host.c
> > > +++ b/hw/pci/pcie_host.c
> > > @@ -24,6 +24,7 @@
> > >  #include "hw/pci/pcie_host.h"
> > >  #include "qemu/module.h"
> > >  #include "exec/address-spaces.h"
> > > +#include "migration/vmstate.h"
> > >  
> > >  /* a helper function to get a PCIDevice for a given mmconfig 
> > > address */  static inline PCIDevice 
> > > *pcie_dev_find_by_mmcfg_addr(PCIBus *s, @@ -121,6 +122,16 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
> > >      memory_region_transaction_commit();
> > >  }
> > >  
> > > +const VMStateDescription vmstate_pciehost = {
> > > +    .name = "PCIEHost",
> > > +    .version_id = 1,
> > > +    .minimum_version_id = 1,
> > > +    .fields = (VMStateField[]) {
> > > +        VMSTATE_PCI_HOST(pci, PCIExpressHost),
> > > +        VMSTATE_END_OF_LIST()
> > > +    }
> > > +};
> > > +
> > >  static const TypeInfo pcie_host_type_info = {
> > >      .name = TYPE_PCIE_HOST_BRIDGE,
> > >      .parent = TYPE_PCI_HOST_BRIDGE, diff --git 
> > > a/include/hw/pci/pci_host.h b/include/hw/pci/pci_host.h index 
> > > 9ce088bd13..fc88305e04 100644
> > > --- a/include/hw/pci/pci_host.h
> > > +++ b/include/hw/pci/pci_host.h
> > > @@ -70,4 +70,14 @@ extern const MemoryRegionOps 
> > > pci_host_conf_be_ops;  extern const MemoryRegionOps 
> > > pci_host_data_le_ops;  extern const MemoryRegionOps 
> > > pci_host_data_be_ops;
> > >  
> > > +extern const VMStateDescription vmstate_pcihost;
> > > +
> > > +#define VMSTATE_PCI_HOST(_field, _state) {                           \
> > > +    .name       = (stringify(_field)),                               \
> > > +    .size       = sizeof(PCIHostState),                              \
> > > +    .vmsd       = &vmstate_pcihost,                                  \
> > > +    .flags      = VMS_STRUCT,                                        \
> > > +    .offset     = vmstate_offset_value(_state, _field, PCIHostState),\
> > > +}
> > > +
> > >  #endif /* PCI_HOST_H */
> > > diff --git a/include/hw/pci/pcie_host.h b/include/hw/pci/pcie_host.h 
> > > index 3f7b9886d1..e8856f03e9 100644
> > > --- a/include/hw/pci/pcie_host.h
> > > +++ b/include/hw/pci/pcie_host.h
> > > @@ -78,4 +78,14 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
> > >                                           PCIE_MMCFG_DEVFN_MASK)
> > >  #define PCIE_MMCFG_CONFOFFSET(addr)     ((addr) & PCIE_MMCFG_CONFOFFSET_MASK)
> > >  
> > > +extern const VMStateDescription vmstate_pciehost;
> > > +
> > > +#define VMSTATE_PCIE_HOST(_field, _state) {                            \
> > > +    .name       = (stringify(_field)),                                 \
> > > +    .size       = sizeof(PCIExpressHost),                              \
> > > +    .vmsd       = &vmstate_pciehost,                                   \
> > > +    .flags      = VMS_STRUCT,                                          \
> > > +    .offset     = vmstate_offset_value(_state, _field, PCIExpressHost),\
> > > +}
> > > +
> > >  #endif /* PCIE_HOST_H */
> > > --
> > > 2.23.0
> > > 
> > 
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: 答复: [PATCH v1] hw/pci-host: save/restore pci host config register
Posted by Michael S. Tsirkin 3 years, 9 months ago
On Thu, Jul 23, 2020 at 02:29:36PM +0000, Wangjing (Hogan, Cloud Infrastructure Service Product Dept.) wrote:
> Wang King wrote:
> > * Michael S. Tsirkin (mst@redhat.com) wrote:
> > > On Thu, Jul 23, 2020 at 08:53:03PM +0800, Wang King wrote:
> > > > From: Hogan Wang <king.wang@huawei.com>
> > > > 
> > > > The pci host config register is used to save PCI address for 
> > > > read/write config data. If guest write a value to config register, 
> > > > and then pause the vcpu to migrate, After the migration, the guest 
> > > > continue to write pci config data, and the write data will be 
> > > > ignored because of new qemu process lost the config register state.
> > > > 
> > > > Reproduction steps are:
> > > > 1. guest booting in seabios.
> > > > 2. guest enable the SMRAM in seabios:piix4_apmc_smm_setup, and then
> > > >    expect to disable the SMRAM by pci_config_writeb.
> > > > 3. after guest write the pci host config register, and then pasued vcpu
> > > >    to finish migration.
> > > > 4. guest write config data(0x0A) fail to disable the SMRAM becasue of
> > > >    config register state lost.
> > > > 5. guest continue to boot and crash in ipxe option ROM due to SMRAM in
> > > >    enabled state.
> > > > 
> > > > Signed-off-by: Hogan Wang <king.wang@huawei.com>
> > > 
> > > I guess this is like v3 right?
> > > 
> > > thanks a lot for the patch!
> > > 
> > > My question stands : does anyone see a way to pass this info around 
> > > without breaking migration for all existing machine types?
> > 
> > You need a .needed clause in the vmstate_i440fx_pcihost and vmstate_q35_pcihost which is a pointer to a function which enables it on new machine types and ignores it on old ones.
> > 
> > Or, if it always crashes if the SMRAM is enabled, then the migration is dead anyway; so you could make the .needed only save the config if the SMRAM is opened, so you'd get a unknown section error, which is nasty but it would only happen in the case it would crash anyway.
> > 
> > Dave
> > 
> 
> It always crashes if the SMRAM is enabled, but it's just one case, config register
> state lost may cause other uncertain errors, so it's need on new machine types.

Well, let's limit this to new machine types for now?
Declaring all machine types broken is unattractive ...

> > > 
> > > > ---
> > > >  hw/pci-host/i440fx.c       | 11 +++++++++++
> > > >  hw/pci-host/q35.c          | 11 +++++++++++
> > > >  hw/pci/pci_host.c          | 11 +++++++++++
> > > >  hw/pci/pcie_host.c         | 11 +++++++++++
> > > >  include/hw/pci/pci_host.h  | 10 ++++++++++  
> > > > include/hw/pci/pcie_host.h | 10 ++++++++++
> > > >  6 files changed, 64 insertions(+)
> > > > 
> > > > diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c index 
> > > > 8ed2417f0c..17705bb025 100644
> > > > --- a/hw/pci-host/i440fx.c
> > > > +++ b/hw/pci-host/i440fx.c
> > > > @@ -118,6 +118,16 @@ static const VMStateDescription vmstate_i440fx = {
> > > >      }
> > > >  };
> > > >  
> > > > +static const VMStateDescription vmstate_i440fx_pcihost = {
> > > > +    .name = "I440FX_PCIHost",
> > > > +    .version_id = 1,
> > > > +    .minimum_version_id = 1,
> > > > +    .fields = (VMStateField[]) {
> > > > +        VMSTATE_PCI_HOST(parent_obj, I440FXState),
> > > > +        VMSTATE_END_OF_LIST()
> > > > +    }
> > > > +};
> > > > +
> > > >  static void i440fx_pcihost_get_pci_hole_start(Object *obj, Visitor *v,
> > > >                                                const char *name, void *opaque,
> > > >                                                Error **errp) @@ 
> > > > -398,6 +408,7 @@ static void i440fx_pcihost_class_init(ObjectClass *klass, void *data)
> > > >      hc->root_bus_path = i440fx_pcihost_root_bus_path;
> > > >      dc->realize = i440fx_pcihost_realize;
> > > >      dc->fw_name = "pci";
> > > > +    dc->vmsd = &vmstate_i440fx_pcihost;
> > > >      device_class_set_props(dc, i440fx_props);
> > > >      /* Reason: needs to be wired up by pc_init1 */
> > > >      dc->user_creatable = false;
> > > > diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c index 
> > > > b67cb9c29f..5e323be2e3 100644
> > > > --- a/hw/pci-host/q35.c
> > > > +++ b/hw/pci-host/q35.c
> > > > @@ -165,6 +165,16 @@ static void q35_host_get_pci_hole64_end(Object *obj, Visitor *v,
> > > >      visit_type_uint64(v, name, &value, errp);  }
> > > >  
> > > > +static const VMStateDescription vmstate_q35_pcihost = {
> > > > +    .name = "Q35_PCIHost",
> > > > +    .version_id = 1,
> > > > +    .minimum_version_id = 1,
> > > > +    .fields = (VMStateField[]) {
> > > > +        VMSTATE_PCIE_HOST(parent_obj, Q35PCIHost),
> > > > +        VMSTATE_END_OF_LIST()
> > > > +    }
> > > > +};
> > > > +
> > > >  /*
> > > >   * NOTE: setting defaults for the mch.* fields in this table
> > > >   * doesn't work, because mch is a separate QOM object that is @@ 
> > > > -194,6 +204,7 @@ static void q35_host_class_init(ObjectClass *klass, 
> > > > void *data)
> > > >  
> > > >      hc->root_bus_path = q35_host_root_bus_path;
> > > >      dc->realize = q35_host_realize;
> > > > +    dc->vmsd = &vmstate_q35_pcihost;
> > > >      device_class_set_props(dc, q35_host_props);
> > > >      /* Reason: needs to be wired up by pc_q35_init */
> > > >      dc->user_creatable = false;
> > > > diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c index 
> > > > ce7bcdb1d5..7cdd5a3ea3 100644
> > > > --- a/hw/pci/pci_host.c
> > > > +++ b/hw/pci/pci_host.c
> > > > @@ -24,6 +24,7 @@
> > > >  #include "hw/pci/pci_host.h"
> > > >  #include "qemu/module.h"
> > > >  #include "hw/pci/pci_bus.h"
> > > > +#include "migration/vmstate.h"
> > > >  #include "trace.h"
> > > >  
> > > >  /* debug PCI */
> > > > @@ -200,6 +201,16 @@ const MemoryRegionOps pci_host_data_be_ops = {
> > > >      .endianness = DEVICE_BIG_ENDIAN,  };
> > > >  
> > > > +const VMStateDescription vmstate_pcihost = {
> > > > +    .name = "PCIHost",
> > > > +    .version_id = 1,
> > > > +    .minimum_version_id = 1,
> > > > +    .fields = (VMStateField[]) {
> > > > +        VMSTATE_UINT32(config_reg, PCIHostState),
> > > > +        VMSTATE_END_OF_LIST()
> > > > +    }
> > > > +};
> > > > +
> > > >  static const TypeInfo pci_host_type_info = {
> > > >      .name = TYPE_PCI_HOST_BRIDGE,
> > > >      .parent = TYPE_SYS_BUS_DEVICE,
> > > > diff --git a/hw/pci/pcie_host.c b/hw/pci/pcie_host.c index 
> > > > 3534006f99..a653c39bb7 100644
> > > > --- a/hw/pci/pcie_host.c
> > > > +++ b/hw/pci/pcie_host.c
> > > > @@ -24,6 +24,7 @@
> > > >  #include "hw/pci/pcie_host.h"
> > > >  #include "qemu/module.h"
> > > >  #include "exec/address-spaces.h"
> > > > +#include "migration/vmstate.h"
> > > >  
> > > >  /* a helper function to get a PCIDevice for a given mmconfig 
> > > > address */  static inline PCIDevice 
> > > > *pcie_dev_find_by_mmcfg_addr(PCIBus *s, @@ -121,6 +122,16 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
> > > >      memory_region_transaction_commit();
> > > >  }
> > > >  
> > > > +const VMStateDescription vmstate_pciehost = {
> > > > +    .name = "PCIEHost",
> > > > +    .version_id = 1,
> > > > +    .minimum_version_id = 1,
> > > > +    .fields = (VMStateField[]) {
> > > > +        VMSTATE_PCI_HOST(pci, PCIExpressHost),
> > > > +        VMSTATE_END_OF_LIST()
> > > > +    }
> > > > +};
> > > > +
> > > >  static const TypeInfo pcie_host_type_info = {
> > > >      .name = TYPE_PCIE_HOST_BRIDGE,
> > > >      .parent = TYPE_PCI_HOST_BRIDGE, diff --git 
> > > > a/include/hw/pci/pci_host.h b/include/hw/pci/pci_host.h index 
> > > > 9ce088bd13..fc88305e04 100644
> > > > --- a/include/hw/pci/pci_host.h
> > > > +++ b/include/hw/pci/pci_host.h
> > > > @@ -70,4 +70,14 @@ extern const MemoryRegionOps 
> > > > pci_host_conf_be_ops;  extern const MemoryRegionOps 
> > > > pci_host_data_le_ops;  extern const MemoryRegionOps 
> > > > pci_host_data_be_ops;
> > > >  
> > > > +extern const VMStateDescription vmstate_pcihost;
> > > > +
> > > > +#define VMSTATE_PCI_HOST(_field, _state) {                           \
> > > > +    .name       = (stringify(_field)),                               \
> > > > +    .size       = sizeof(PCIHostState),                              \
> > > > +    .vmsd       = &vmstate_pcihost,                                  \
> > > > +    .flags      = VMS_STRUCT,                                        \
> > > > +    .offset     = vmstate_offset_value(_state, _field, PCIHostState),\
> > > > +}
> > > > +
> > > >  #endif /* PCI_HOST_H */
> > > > diff --git a/include/hw/pci/pcie_host.h b/include/hw/pci/pcie_host.h 
> > > > index 3f7b9886d1..e8856f03e9 100644
> > > > --- a/include/hw/pci/pcie_host.h
> > > > +++ b/include/hw/pci/pcie_host.h
> > > > @@ -78,4 +78,14 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
> > > >                                           PCIE_MMCFG_DEVFN_MASK)
> > > >  #define PCIE_MMCFG_CONFOFFSET(addr)     ((addr) & PCIE_MMCFG_CONFOFFSET_MASK)
> > > >  
> > > > +extern const VMStateDescription vmstate_pciehost;
> > > > +
> > > > +#define VMSTATE_PCIE_HOST(_field, _state) {                            \
> > > > +    .name       = (stringify(_field)),                                 \
> > > > +    .size       = sizeof(PCIExpressHost),                              \
> > > > +    .vmsd       = &vmstate_pciehost,                                   \
> > > > +    .flags      = VMS_STRUCT,                                          \
> > > > +    .offset     = vmstate_offset_value(_state, _field, PCIExpressHost),\
> > > > +}
> > > > +
> > > >  #endif /* PCIE_HOST_H */
> > > > --
> > > > 2.23.0
> > > > 
> > > 
> > --
> > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> 


Re: [PATCH v1] hw/pci-host: save/restore pci host config register
Posted by Michael S. Tsirkin 3 years, 9 months ago
On Thu, Jul 23, 2020 at 02:12:54PM +0100, Dr. David Alan Gilbert wrote:
> * Michael S. Tsirkin (mst@redhat.com) wrote:
> > On Thu, Jul 23, 2020 at 08:53:03PM +0800, Wang King wrote:
> > > From: Hogan Wang <king.wang@huawei.com>
> > > 
> > > The pci host config register is used to save PCI address for
> > > read/write config data. If guest write a value to config register,
> > > and then pause the vcpu to migrate, After the migration, the guest
> > > continue to write pci config data, and the write data will be ignored
> > > because of new qemu process lost the config register state.
> > > 
> > > Reproduction steps are:
> > > 1. guest booting in seabios.
> > > 2. guest enable the SMRAM in seabios:piix4_apmc_smm_setup, and then
> > >    expect to disable the SMRAM by pci_config_writeb.
> > > 3. after guest write the pci host config register, and then pasued vcpu
> > >    to finish migration.
> > > 4. guest write config data(0x0A) fail to disable the SMRAM becasue of
> > >    config register state lost.
> > > 5. guest continue to boot and crash in ipxe option ROM due to SMRAM in
> > >    enabled state.
> > > 
> > > Signed-off-by: Hogan Wang <king.wang@huawei.com>
> > 
> > I guess this is like v3 right?
> > 
> > thanks a lot for the patch!
> > 
> > My question stands : does anyone see a way to pass this
> > info around without breaking migration for all existing
> > machine types?
> 
> You need a .needed clause in the vmstate_i440fx_pcihost and
> vmstate_q35_pcihost which is a pointer to a function which enables it on
> new machine types and ignores it on old ones.
> 
> Or, if it always crashes if the SMRAM is enabled, then the migration is
> dead anyway; so you could make the .needed only save the config if
> the SMRAM is opened, so you'd get a unknown section error, which is
> nasty but it would only happen in the case it would crash anyway.
> 
> Dave

Problem is we never know whether it's needed.

For example: guest programs cf8, then cfc.
Guest on destination can crash if migrated after
writing cf8 before writing cfc.
But in theory it can also crash if guest assumes
cf8 is unchanged and just writes cfc.

So what I'd prefer to do is put it in some data that
old qemu ignores. Then once qemu on destination
is updated, it will start interpreting it.


> > 
> > > ---
> > >  hw/pci-host/i440fx.c       | 11 +++++++++++
> > >  hw/pci-host/q35.c          | 11 +++++++++++
> > >  hw/pci/pci_host.c          | 11 +++++++++++
> > >  hw/pci/pcie_host.c         | 11 +++++++++++
> > >  include/hw/pci/pci_host.h  | 10 ++++++++++
> > >  include/hw/pci/pcie_host.h | 10 ++++++++++
> > >  6 files changed, 64 insertions(+)
> > > 
> > > diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c
> > > index 8ed2417f0c..17705bb025 100644
> > > --- a/hw/pci-host/i440fx.c
> > > +++ b/hw/pci-host/i440fx.c
> > > @@ -118,6 +118,16 @@ static const VMStateDescription vmstate_i440fx = {
> > >      }
> > >  };
> > >  
> > > +static const VMStateDescription vmstate_i440fx_pcihost = {
> > > +    .name = "I440FX_PCIHost",
> > > +    .version_id = 1,
> > > +    .minimum_version_id = 1,
> > > +    .fields = (VMStateField[]) {
> > > +        VMSTATE_PCI_HOST(parent_obj, I440FXState),
> > > +        VMSTATE_END_OF_LIST()
> > > +    }
> > > +};
> > > +
> > >  static void i440fx_pcihost_get_pci_hole_start(Object *obj, Visitor *v,
> > >                                                const char *name, void *opaque,
> > >                                                Error **errp)
> > > @@ -398,6 +408,7 @@ static void i440fx_pcihost_class_init(ObjectClass *klass, void *data)
> > >      hc->root_bus_path = i440fx_pcihost_root_bus_path;
> > >      dc->realize = i440fx_pcihost_realize;
> > >      dc->fw_name = "pci";
> > > +    dc->vmsd = &vmstate_i440fx_pcihost;
> > >      device_class_set_props(dc, i440fx_props);
> > >      /* Reason: needs to be wired up by pc_init1 */
> > >      dc->user_creatable = false;
> > > diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
> > > index b67cb9c29f..5e323be2e3 100644
> > > --- a/hw/pci-host/q35.c
> > > +++ b/hw/pci-host/q35.c
> > > @@ -165,6 +165,16 @@ static void q35_host_get_pci_hole64_end(Object *obj, Visitor *v,
> > >      visit_type_uint64(v, name, &value, errp);
> > >  }
> > >  
> > > +static const VMStateDescription vmstate_q35_pcihost = {
> > > +    .name = "Q35_PCIHost",
> > > +    .version_id = 1,
> > > +    .minimum_version_id = 1,
> > > +    .fields = (VMStateField[]) {
> > > +        VMSTATE_PCIE_HOST(parent_obj, Q35PCIHost),
> > > +        VMSTATE_END_OF_LIST()
> > > +    }
> > > +};
> > > +
> > >  /*
> > >   * NOTE: setting defaults for the mch.* fields in this table
> > >   * doesn't work, because mch is a separate QOM object that is
> > > @@ -194,6 +204,7 @@ static void q35_host_class_init(ObjectClass *klass, void *data)
> > >  
> > >      hc->root_bus_path = q35_host_root_bus_path;
> > >      dc->realize = q35_host_realize;
> > > +    dc->vmsd = &vmstate_q35_pcihost;
> > >      device_class_set_props(dc, q35_host_props);
> > >      /* Reason: needs to be wired up by pc_q35_init */
> > >      dc->user_creatable = false;
> > > diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
> > > index ce7bcdb1d5..7cdd5a3ea3 100644
> > > --- a/hw/pci/pci_host.c
> > > +++ b/hw/pci/pci_host.c
> > > @@ -24,6 +24,7 @@
> > >  #include "hw/pci/pci_host.h"
> > >  #include "qemu/module.h"
> > >  #include "hw/pci/pci_bus.h"
> > > +#include "migration/vmstate.h"
> > >  #include "trace.h"
> > >  
> > >  /* debug PCI */
> > > @@ -200,6 +201,16 @@ const MemoryRegionOps pci_host_data_be_ops = {
> > >      .endianness = DEVICE_BIG_ENDIAN,
> > >  };
> > >  
> > > +const VMStateDescription vmstate_pcihost = {
> > > +    .name = "PCIHost",
> > > +    .version_id = 1,
> > > +    .minimum_version_id = 1,
> > > +    .fields = (VMStateField[]) {
> > > +        VMSTATE_UINT32(config_reg, PCIHostState),
> > > +        VMSTATE_END_OF_LIST()
> > > +    }
> > > +};
> > > +
> > >  static const TypeInfo pci_host_type_info = {
> > >      .name = TYPE_PCI_HOST_BRIDGE,
> > >      .parent = TYPE_SYS_BUS_DEVICE,
> > > diff --git a/hw/pci/pcie_host.c b/hw/pci/pcie_host.c
> > > index 3534006f99..a653c39bb7 100644
> > > --- a/hw/pci/pcie_host.c
> > > +++ b/hw/pci/pcie_host.c
> > > @@ -24,6 +24,7 @@
> > >  #include "hw/pci/pcie_host.h"
> > >  #include "qemu/module.h"
> > >  #include "exec/address-spaces.h"
> > > +#include "migration/vmstate.h"
> > >  
> > >  /* a helper function to get a PCIDevice for a given mmconfig address */
> > >  static inline PCIDevice *pcie_dev_find_by_mmcfg_addr(PCIBus *s,
> > > @@ -121,6 +122,16 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
> > >      memory_region_transaction_commit();
> > >  }
> > >  
> > > +const VMStateDescription vmstate_pciehost = {
> > > +    .name = "PCIEHost",
> > > +    .version_id = 1,
> > > +    .minimum_version_id = 1,
> > > +    .fields = (VMStateField[]) {
> > > +        VMSTATE_PCI_HOST(pci, PCIExpressHost),
> > > +        VMSTATE_END_OF_LIST()
> > > +    }
> > > +};
> > > +
> > >  static const TypeInfo pcie_host_type_info = {
> > >      .name = TYPE_PCIE_HOST_BRIDGE,
> > >      .parent = TYPE_PCI_HOST_BRIDGE,
> > > diff --git a/include/hw/pci/pci_host.h b/include/hw/pci/pci_host.h
> > > index 9ce088bd13..fc88305e04 100644
> > > --- a/include/hw/pci/pci_host.h
> > > +++ b/include/hw/pci/pci_host.h
> > > @@ -70,4 +70,14 @@ extern const MemoryRegionOps pci_host_conf_be_ops;
> > >  extern const MemoryRegionOps pci_host_data_le_ops;
> > >  extern const MemoryRegionOps pci_host_data_be_ops;
> > >  
> > > +extern const VMStateDescription vmstate_pcihost;
> > > +
> > > +#define VMSTATE_PCI_HOST(_field, _state) {                           \
> > > +    .name       = (stringify(_field)),                               \
> > > +    .size       = sizeof(PCIHostState),                              \
> > > +    .vmsd       = &vmstate_pcihost,                                  \
> > > +    .flags      = VMS_STRUCT,                                        \
> > > +    .offset     = vmstate_offset_value(_state, _field, PCIHostState),\
> > > +}
> > > +
> > >  #endif /* PCI_HOST_H */
> > > diff --git a/include/hw/pci/pcie_host.h b/include/hw/pci/pcie_host.h
> > > index 3f7b9886d1..e8856f03e9 100644
> > > --- a/include/hw/pci/pcie_host.h
> > > +++ b/include/hw/pci/pcie_host.h
> > > @@ -78,4 +78,14 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
> > >                                           PCIE_MMCFG_DEVFN_MASK)
> > >  #define PCIE_MMCFG_CONFOFFSET(addr)     ((addr) & PCIE_MMCFG_CONFOFFSET_MASK)
> > >  
> > > +extern const VMStateDescription vmstate_pciehost;
> > > +
> > > +#define VMSTATE_PCIE_HOST(_field, _state) {                            \
> > > +    .name       = (stringify(_field)),                                 \
> > > +    .size       = sizeof(PCIExpressHost),                              \
> > > +    .vmsd       = &vmstate_pciehost,                                   \
> > > +    .flags      = VMS_STRUCT,                                          \
> > > +    .offset     = vmstate_offset_value(_state, _field, PCIExpressHost),\
> > > +}
> > > +
> > >  #endif /* PCIE_HOST_H */
> > > -- 
> > > 2.23.0
> > > 
> > 
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK


Re: [PATCH v1] hw/pci-host: save/restore pci host config register
Posted by Dr. David Alan Gilbert 3 years, 9 months ago
* Michael S. Tsirkin (mst@redhat.com) wrote:
> On Thu, Jul 23, 2020 at 02:12:54PM +0100, Dr. David Alan Gilbert wrote:
> > * Michael S. Tsirkin (mst@redhat.com) wrote:
> > > On Thu, Jul 23, 2020 at 08:53:03PM +0800, Wang King wrote:
> > > > From: Hogan Wang <king.wang@huawei.com>
> > > > 
> > > > The pci host config register is used to save PCI address for
> > > > read/write config data. If guest write a value to config register,
> > > > and then pause the vcpu to migrate, After the migration, the guest
> > > > continue to write pci config data, and the write data will be ignored
> > > > because of new qemu process lost the config register state.
> > > > 
> > > > Reproduction steps are:
> > > > 1. guest booting in seabios.
> > > > 2. guest enable the SMRAM in seabios:piix4_apmc_smm_setup, and then
> > > >    expect to disable the SMRAM by pci_config_writeb.
> > > > 3. after guest write the pci host config register, and then pasued vcpu
> > > >    to finish migration.
> > > > 4. guest write config data(0x0A) fail to disable the SMRAM becasue of
> > > >    config register state lost.
> > > > 5. guest continue to boot and crash in ipxe option ROM due to SMRAM in
> > > >    enabled state.
> > > > 
> > > > Signed-off-by: Hogan Wang <king.wang@huawei.com>
> > > 
> > > I guess this is like v3 right?
> > > 
> > > thanks a lot for the patch!
> > > 
> > > My question stands : does anyone see a way to pass this
> > > info around without breaking migration for all existing
> > > machine types?
> > 
> > You need a .needed clause in the vmstate_i440fx_pcihost and
> > vmstate_q35_pcihost which is a pointer to a function which enables it on
> > new machine types and ignores it on old ones.
> > 
> > Or, if it always crashes if the SMRAM is enabled, then the migration is
> > dead anyway; so you could make the .needed only save the config if
> > the SMRAM is opened, so you'd get a unknown section error, which is
> > nasty but it would only happen in the case it would crash anyway.
> > 
> > Dave
> 
> Problem is we never know whether it's needed.
> 
> For example: guest programs cf8, then cfc.
> Guest on destination can crash if migrated after
> writing cf8 before writing cfc.
> But in theory it can also crash if guest assumes
> cf8 is unchanged and just writes cfc.
> 
> So what I'd prefer to do is put it in some data that
> old qemu ignores. Then once qemu on destination
> is updated, it will start interpreting it.

We don't have a way to do that; the choice is:
  a) Not sending it for old versions, so you only get the
    fix for new machine types

  b) Trying to second guess when it will crash

I recommend (a) generally - but the format has no
way to ignore unknown data.

Dave

> 
> > > 
> > > > ---
> > > >  hw/pci-host/i440fx.c       | 11 +++++++++++
> > > >  hw/pci-host/q35.c          | 11 +++++++++++
> > > >  hw/pci/pci_host.c          | 11 +++++++++++
> > > >  hw/pci/pcie_host.c         | 11 +++++++++++
> > > >  include/hw/pci/pci_host.h  | 10 ++++++++++
> > > >  include/hw/pci/pcie_host.h | 10 ++++++++++
> > > >  6 files changed, 64 insertions(+)
> > > > 
> > > > diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c
> > > > index 8ed2417f0c..17705bb025 100644
> > > > --- a/hw/pci-host/i440fx.c
> > > > +++ b/hw/pci-host/i440fx.c
> > > > @@ -118,6 +118,16 @@ static const VMStateDescription vmstate_i440fx = {
> > > >      }
> > > >  };
> > > >  
> > > > +static const VMStateDescription vmstate_i440fx_pcihost = {
> > > > +    .name = "I440FX_PCIHost",
> > > > +    .version_id = 1,
> > > > +    .minimum_version_id = 1,
> > > > +    .fields = (VMStateField[]) {
> > > > +        VMSTATE_PCI_HOST(parent_obj, I440FXState),
> > > > +        VMSTATE_END_OF_LIST()
> > > > +    }
> > > > +};
> > > > +
> > > >  static void i440fx_pcihost_get_pci_hole_start(Object *obj, Visitor *v,
> > > >                                                const char *name, void *opaque,
> > > >                                                Error **errp)
> > > > @@ -398,6 +408,7 @@ static void i440fx_pcihost_class_init(ObjectClass *klass, void *data)
> > > >      hc->root_bus_path = i440fx_pcihost_root_bus_path;
> > > >      dc->realize = i440fx_pcihost_realize;
> > > >      dc->fw_name = "pci";
> > > > +    dc->vmsd = &vmstate_i440fx_pcihost;
> > > >      device_class_set_props(dc, i440fx_props);
> > > >      /* Reason: needs to be wired up by pc_init1 */
> > > >      dc->user_creatable = false;
> > > > diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
> > > > index b67cb9c29f..5e323be2e3 100644
> > > > --- a/hw/pci-host/q35.c
> > > > +++ b/hw/pci-host/q35.c
> > > > @@ -165,6 +165,16 @@ static void q35_host_get_pci_hole64_end(Object *obj, Visitor *v,
> > > >      visit_type_uint64(v, name, &value, errp);
> > > >  }
> > > >  
> > > > +static const VMStateDescription vmstate_q35_pcihost = {
> > > > +    .name = "Q35_PCIHost",
> > > > +    .version_id = 1,
> > > > +    .minimum_version_id = 1,
> > > > +    .fields = (VMStateField[]) {
> > > > +        VMSTATE_PCIE_HOST(parent_obj, Q35PCIHost),
> > > > +        VMSTATE_END_OF_LIST()
> > > > +    }
> > > > +};
> > > > +
> > > >  /*
> > > >   * NOTE: setting defaults for the mch.* fields in this table
> > > >   * doesn't work, because mch is a separate QOM object that is
> > > > @@ -194,6 +204,7 @@ static void q35_host_class_init(ObjectClass *klass, void *data)
> > > >  
> > > >      hc->root_bus_path = q35_host_root_bus_path;
> > > >      dc->realize = q35_host_realize;
> > > > +    dc->vmsd = &vmstate_q35_pcihost;
> > > >      device_class_set_props(dc, q35_host_props);
> > > >      /* Reason: needs to be wired up by pc_q35_init */
> > > >      dc->user_creatable = false;
> > > > diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
> > > > index ce7bcdb1d5..7cdd5a3ea3 100644
> > > > --- a/hw/pci/pci_host.c
> > > > +++ b/hw/pci/pci_host.c
> > > > @@ -24,6 +24,7 @@
> > > >  #include "hw/pci/pci_host.h"
> > > >  #include "qemu/module.h"
> > > >  #include "hw/pci/pci_bus.h"
> > > > +#include "migration/vmstate.h"
> > > >  #include "trace.h"
> > > >  
> > > >  /* debug PCI */
> > > > @@ -200,6 +201,16 @@ const MemoryRegionOps pci_host_data_be_ops = {
> > > >      .endianness = DEVICE_BIG_ENDIAN,
> > > >  };
> > > >  
> > > > +const VMStateDescription vmstate_pcihost = {
> > > > +    .name = "PCIHost",
> > > > +    .version_id = 1,
> > > > +    .minimum_version_id = 1,
> > > > +    .fields = (VMStateField[]) {
> > > > +        VMSTATE_UINT32(config_reg, PCIHostState),
> > > > +        VMSTATE_END_OF_LIST()
> > > > +    }
> > > > +};
> > > > +
> > > >  static const TypeInfo pci_host_type_info = {
> > > >      .name = TYPE_PCI_HOST_BRIDGE,
> > > >      .parent = TYPE_SYS_BUS_DEVICE,
> > > > diff --git a/hw/pci/pcie_host.c b/hw/pci/pcie_host.c
> > > > index 3534006f99..a653c39bb7 100644
> > > > --- a/hw/pci/pcie_host.c
> > > > +++ b/hw/pci/pcie_host.c
> > > > @@ -24,6 +24,7 @@
> > > >  #include "hw/pci/pcie_host.h"
> > > >  #include "qemu/module.h"
> > > >  #include "exec/address-spaces.h"
> > > > +#include "migration/vmstate.h"
> > > >  
> > > >  /* a helper function to get a PCIDevice for a given mmconfig address */
> > > >  static inline PCIDevice *pcie_dev_find_by_mmcfg_addr(PCIBus *s,
> > > > @@ -121,6 +122,16 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
> > > >      memory_region_transaction_commit();
> > > >  }
> > > >  
> > > > +const VMStateDescription vmstate_pciehost = {
> > > > +    .name = "PCIEHost",
> > > > +    .version_id = 1,
> > > > +    .minimum_version_id = 1,
> > > > +    .fields = (VMStateField[]) {
> > > > +        VMSTATE_PCI_HOST(pci, PCIExpressHost),
> > > > +        VMSTATE_END_OF_LIST()
> > > > +    }
> > > > +};
> > > > +
> > > >  static const TypeInfo pcie_host_type_info = {
> > > >      .name = TYPE_PCIE_HOST_BRIDGE,
> > > >      .parent = TYPE_PCI_HOST_BRIDGE,
> > > > diff --git a/include/hw/pci/pci_host.h b/include/hw/pci/pci_host.h
> > > > index 9ce088bd13..fc88305e04 100644
> > > > --- a/include/hw/pci/pci_host.h
> > > > +++ b/include/hw/pci/pci_host.h
> > > > @@ -70,4 +70,14 @@ extern const MemoryRegionOps pci_host_conf_be_ops;
> > > >  extern const MemoryRegionOps pci_host_data_le_ops;
> > > >  extern const MemoryRegionOps pci_host_data_be_ops;
> > > >  
> > > > +extern const VMStateDescription vmstate_pcihost;
> > > > +
> > > > +#define VMSTATE_PCI_HOST(_field, _state) {                           \
> > > > +    .name       = (stringify(_field)),                               \
> > > > +    .size       = sizeof(PCIHostState),                              \
> > > > +    .vmsd       = &vmstate_pcihost,                                  \
> > > > +    .flags      = VMS_STRUCT,                                        \
> > > > +    .offset     = vmstate_offset_value(_state, _field, PCIHostState),\
> > > > +}
> > > > +
> > > >  #endif /* PCI_HOST_H */
> > > > diff --git a/include/hw/pci/pcie_host.h b/include/hw/pci/pcie_host.h
> > > > index 3f7b9886d1..e8856f03e9 100644
> > > > --- a/include/hw/pci/pcie_host.h
> > > > +++ b/include/hw/pci/pcie_host.h
> > > > @@ -78,4 +78,14 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
> > > >                                           PCIE_MMCFG_DEVFN_MASK)
> > > >  #define PCIE_MMCFG_CONFOFFSET(addr)     ((addr) & PCIE_MMCFG_CONFOFFSET_MASK)
> > > >  
> > > > +extern const VMStateDescription vmstate_pciehost;
> > > > +
> > > > +#define VMSTATE_PCIE_HOST(_field, _state) {                            \
> > > > +    .name       = (stringify(_field)),                                 \
> > > > +    .size       = sizeof(PCIExpressHost),                              \
> > > > +    .vmsd       = &vmstate_pciehost,                                   \
> > > > +    .flags      = VMS_STRUCT,                                          \
> > > > +    .offset     = vmstate_offset_value(_state, _field, PCIExpressHost),\
> > > > +}
> > > > +
> > > >  #endif /* PCIE_HOST_H */
> > > > -- 
> > > > 2.23.0
> > > > 
> > > 
> > --
> > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK


Re: [PATCH v1] hw/pci-host: save/restore pci host config register
Posted by Michael S. Tsirkin 3 years, 9 months ago
On Thu, Jul 23, 2020 at 05:04:53PM +0100, Dr. David Alan Gilbert wrote:
> * Michael S. Tsirkin (mst@redhat.com) wrote:
> > On Thu, Jul 23, 2020 at 02:12:54PM +0100, Dr. David Alan Gilbert wrote:
> > > * Michael S. Tsirkin (mst@redhat.com) wrote:
> > > > On Thu, Jul 23, 2020 at 08:53:03PM +0800, Wang King wrote:
> > > > > From: Hogan Wang <king.wang@huawei.com>
> > > > > 
> > > > > The pci host config register is used to save PCI address for
> > > > > read/write config data. If guest write a value to config register,
> > > > > and then pause the vcpu to migrate, After the migration, the guest
> > > > > continue to write pci config data, and the write data will be ignored
> > > > > because of new qemu process lost the config register state.
> > > > > 
> > > > > Reproduction steps are:
> > > > > 1. guest booting in seabios.
> > > > > 2. guest enable the SMRAM in seabios:piix4_apmc_smm_setup, and then
> > > > >    expect to disable the SMRAM by pci_config_writeb.
> > > > > 3. after guest write the pci host config register, and then pasued vcpu
> > > > >    to finish migration.
> > > > > 4. guest write config data(0x0A) fail to disable the SMRAM becasue of
> > > > >    config register state lost.
> > > > > 5. guest continue to boot and crash in ipxe option ROM due to SMRAM in
> > > > >    enabled state.
> > > > > 
> > > > > Signed-off-by: Hogan Wang <king.wang@huawei.com>
> > > > 
> > > > I guess this is like v3 right?
> > > > 
> > > > thanks a lot for the patch!
> > > > 
> > > > My question stands : does anyone see a way to pass this
> > > > info around without breaking migration for all existing
> > > > machine types?
> > > 
> > > You need a .needed clause in the vmstate_i440fx_pcihost and
> > > vmstate_q35_pcihost which is a pointer to a function which enables it on
> > > new machine types and ignores it on old ones.
> > > 
> > > Or, if it always crashes if the SMRAM is enabled, then the migration is
> > > dead anyway; so you could make the .needed only save the config if
> > > the SMRAM is opened, so you'd get a unknown section error, which is
> > > nasty but it would only happen in the case it would crash anyway.
> > > 
> > > Dave
> > 
> > Problem is we never know whether it's needed.
> > 
> > For example: guest programs cf8, then cfc.
> > Guest on destination can crash if migrated after
> > writing cf8 before writing cfc.
> > But in theory it can also crash if guest assumes
> > cf8 is unchanged and just writes cfc.
> > 
> > So what I'd prefer to do is put it in some data that
> > old qemu ignores. Then once qemu on destination
> > is updated, it will start interpreting it.
> 
> We don't have a way to do that; the choice is:
>   a) Not sending it for old versions, so you only get the
>     fix for new machine types
> 
>   b) Trying to second guess when it will crash
> 
> I recommend (a) generally - but the format has no
> way to ignore unknown data.
> 
> Dave

How about adding that finally, so we have a way to fix bugs like this one?

> > 
> > > > 
> > > > > ---
> > > > >  hw/pci-host/i440fx.c       | 11 +++++++++++
> > > > >  hw/pci-host/q35.c          | 11 +++++++++++
> > > > >  hw/pci/pci_host.c          | 11 +++++++++++
> > > > >  hw/pci/pcie_host.c         | 11 +++++++++++
> > > > >  include/hw/pci/pci_host.h  | 10 ++++++++++
> > > > >  include/hw/pci/pcie_host.h | 10 ++++++++++
> > > > >  6 files changed, 64 insertions(+)
> > > > > 
> > > > > diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c
> > > > > index 8ed2417f0c..17705bb025 100644
> > > > > --- a/hw/pci-host/i440fx.c
> > > > > +++ b/hw/pci-host/i440fx.c
> > > > > @@ -118,6 +118,16 @@ static const VMStateDescription vmstate_i440fx = {
> > > > >      }
> > > > >  };
> > > > >  
> > > > > +static const VMStateDescription vmstate_i440fx_pcihost = {
> > > > > +    .name = "I440FX_PCIHost",
> > > > > +    .version_id = 1,
> > > > > +    .minimum_version_id = 1,
> > > > > +    .fields = (VMStateField[]) {
> > > > > +        VMSTATE_PCI_HOST(parent_obj, I440FXState),
> > > > > +        VMSTATE_END_OF_LIST()
> > > > > +    }
> > > > > +};
> > > > > +
> > > > >  static void i440fx_pcihost_get_pci_hole_start(Object *obj, Visitor *v,
> > > > >                                                const char *name, void *opaque,
> > > > >                                                Error **errp)
> > > > > @@ -398,6 +408,7 @@ static void i440fx_pcihost_class_init(ObjectClass *klass, void *data)
> > > > >      hc->root_bus_path = i440fx_pcihost_root_bus_path;
> > > > >      dc->realize = i440fx_pcihost_realize;
> > > > >      dc->fw_name = "pci";
> > > > > +    dc->vmsd = &vmstate_i440fx_pcihost;
> > > > >      device_class_set_props(dc, i440fx_props);
> > > > >      /* Reason: needs to be wired up by pc_init1 */
> > > > >      dc->user_creatable = false;
> > > > > diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
> > > > > index b67cb9c29f..5e323be2e3 100644
> > > > > --- a/hw/pci-host/q35.c
> > > > > +++ b/hw/pci-host/q35.c
> > > > > @@ -165,6 +165,16 @@ static void q35_host_get_pci_hole64_end(Object *obj, Visitor *v,
> > > > >      visit_type_uint64(v, name, &value, errp);
> > > > >  }
> > > > >  
> > > > > +static const VMStateDescription vmstate_q35_pcihost = {
> > > > > +    .name = "Q35_PCIHost",
> > > > > +    .version_id = 1,
> > > > > +    .minimum_version_id = 1,
> > > > > +    .fields = (VMStateField[]) {
> > > > > +        VMSTATE_PCIE_HOST(parent_obj, Q35PCIHost),
> > > > > +        VMSTATE_END_OF_LIST()
> > > > > +    }
> > > > > +};
> > > > > +
> > > > >  /*
> > > > >   * NOTE: setting defaults for the mch.* fields in this table
> > > > >   * doesn't work, because mch is a separate QOM object that is
> > > > > @@ -194,6 +204,7 @@ static void q35_host_class_init(ObjectClass *klass, void *data)
> > > > >  
> > > > >      hc->root_bus_path = q35_host_root_bus_path;
> > > > >      dc->realize = q35_host_realize;
> > > > > +    dc->vmsd = &vmstate_q35_pcihost;
> > > > >      device_class_set_props(dc, q35_host_props);
> > > > >      /* Reason: needs to be wired up by pc_q35_init */
> > > > >      dc->user_creatable = false;
> > > > > diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
> > > > > index ce7bcdb1d5..7cdd5a3ea3 100644
> > > > > --- a/hw/pci/pci_host.c
> > > > > +++ b/hw/pci/pci_host.c
> > > > > @@ -24,6 +24,7 @@
> > > > >  #include "hw/pci/pci_host.h"
> > > > >  #include "qemu/module.h"
> > > > >  #include "hw/pci/pci_bus.h"
> > > > > +#include "migration/vmstate.h"
> > > > >  #include "trace.h"
> > > > >  
> > > > >  /* debug PCI */
> > > > > @@ -200,6 +201,16 @@ const MemoryRegionOps pci_host_data_be_ops = {
> > > > >      .endianness = DEVICE_BIG_ENDIAN,
> > > > >  };
> > > > >  
> > > > > +const VMStateDescription vmstate_pcihost = {
> > > > > +    .name = "PCIHost",
> > > > > +    .version_id = 1,
> > > > > +    .minimum_version_id = 1,
> > > > > +    .fields = (VMStateField[]) {
> > > > > +        VMSTATE_UINT32(config_reg, PCIHostState),
> > > > > +        VMSTATE_END_OF_LIST()
> > > > > +    }
> > > > > +};
> > > > > +
> > > > >  static const TypeInfo pci_host_type_info = {
> > > > >      .name = TYPE_PCI_HOST_BRIDGE,
> > > > >      .parent = TYPE_SYS_BUS_DEVICE,
> > > > > diff --git a/hw/pci/pcie_host.c b/hw/pci/pcie_host.c
> > > > > index 3534006f99..a653c39bb7 100644
> > > > > --- a/hw/pci/pcie_host.c
> > > > > +++ b/hw/pci/pcie_host.c
> > > > > @@ -24,6 +24,7 @@
> > > > >  #include "hw/pci/pcie_host.h"
> > > > >  #include "qemu/module.h"
> > > > >  #include "exec/address-spaces.h"
> > > > > +#include "migration/vmstate.h"
> > > > >  
> > > > >  /* a helper function to get a PCIDevice for a given mmconfig address */
> > > > >  static inline PCIDevice *pcie_dev_find_by_mmcfg_addr(PCIBus *s,
> > > > > @@ -121,6 +122,16 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
> > > > >      memory_region_transaction_commit();
> > > > >  }
> > > > >  
> > > > > +const VMStateDescription vmstate_pciehost = {
> > > > > +    .name = "PCIEHost",
> > > > > +    .version_id = 1,
> > > > > +    .minimum_version_id = 1,
> > > > > +    .fields = (VMStateField[]) {
> > > > > +        VMSTATE_PCI_HOST(pci, PCIExpressHost),
> > > > > +        VMSTATE_END_OF_LIST()
> > > > > +    }
> > > > > +};
> > > > > +
> > > > >  static const TypeInfo pcie_host_type_info = {
> > > > >      .name = TYPE_PCIE_HOST_BRIDGE,
> > > > >      .parent = TYPE_PCI_HOST_BRIDGE,
> > > > > diff --git a/include/hw/pci/pci_host.h b/include/hw/pci/pci_host.h
> > > > > index 9ce088bd13..fc88305e04 100644
> > > > > --- a/include/hw/pci/pci_host.h
> > > > > +++ b/include/hw/pci/pci_host.h
> > > > > @@ -70,4 +70,14 @@ extern const MemoryRegionOps pci_host_conf_be_ops;
> > > > >  extern const MemoryRegionOps pci_host_data_le_ops;
> > > > >  extern const MemoryRegionOps pci_host_data_be_ops;
> > > > >  
> > > > > +extern const VMStateDescription vmstate_pcihost;
> > > > > +
> > > > > +#define VMSTATE_PCI_HOST(_field, _state) {                           \
> > > > > +    .name       = (stringify(_field)),                               \
> > > > > +    .size       = sizeof(PCIHostState),                              \
> > > > > +    .vmsd       = &vmstate_pcihost,                                  \
> > > > > +    .flags      = VMS_STRUCT,                                        \
> > > > > +    .offset     = vmstate_offset_value(_state, _field, PCIHostState),\
> > > > > +}
> > > > > +
> > > > >  #endif /* PCI_HOST_H */
> > > > > diff --git a/include/hw/pci/pcie_host.h b/include/hw/pci/pcie_host.h
> > > > > index 3f7b9886d1..e8856f03e9 100644
> > > > > --- a/include/hw/pci/pcie_host.h
> > > > > +++ b/include/hw/pci/pcie_host.h
> > > > > @@ -78,4 +78,14 @@ void pcie_host_mmcfg_update(PCIExpressHost *e,
> > > > >                                           PCIE_MMCFG_DEVFN_MASK)
> > > > >  #define PCIE_MMCFG_CONFOFFSET(addr)     ((addr) & PCIE_MMCFG_CONFOFFSET_MASK)
> > > > >  
> > > > > +extern const VMStateDescription vmstate_pciehost;
> > > > > +
> > > > > +#define VMSTATE_PCIE_HOST(_field, _state) {                            \
> > > > > +    .name       = (stringify(_field)),                                 \
> > > > > +    .size       = sizeof(PCIExpressHost),                              \
> > > > > +    .vmsd       = &vmstate_pciehost,                                   \
> > > > > +    .flags      = VMS_STRUCT,                                          \
> > > > > +    .offset     = vmstate_offset_value(_state, _field, PCIExpressHost),\
> > > > > +}
> > > > > +
> > > > >  #endif /* PCIE_HOST_H */
> > > > > -- 
> > > > > 2.23.0
> > > > > 
> > > > 
> > > --
> > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> > 
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK