hw/core/qdev.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
When Libvirt start, it get the vcpu's unavailable-features from
/machine/unattached/device[0] path by qom-get command, but in SGX
guest, since the sgx-epc virtual device is initialized before VCPU
creation(virtual sgx need set the virtual EPC info in the cpuid). This
/machine/unattached/device[0] is occupied by sgx-epc device, which
fail to get the unvailable-features from /machine/unattached/device[0].
This patch make one new /machine/sgx object to avoid this issue.
(qemu) qom-list /machine/unattached/
device[0] (child<host-x86_64-cpu>)
(qemu) qom-list /machine/sgx
device[0] (child<sgx-epc>)
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
---
hw/core/qdev.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 84f3019440..4154eef0d8 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -497,7 +497,7 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
NamedClockList *ncl;
Error *local_err = NULL;
bool unattached_parent = false;
- static int unattached_count;
+ static int unattached_count, sgx_count;
if (dev->hotplugged && !dc->hotpluggable) {
error_setg(errp, QERR_DEVICE_NO_HOTPLUG, object_get_typename(obj));
@@ -509,7 +509,15 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
goto fail;
}
- if (!obj->parent) {
+ if (!obj->parent && !strcmp(object_get_typename(obj), "sgx-epc")) {
+ gchar *name = g_strdup_printf("device[%d]", sgx_count++);
+
+ object_property_add_child(container_get(qdev_get_machine(),
+ "/sgx"),
+ name, obj);
+ unattached_parent = true;
+ g_free(name);
+ } else if (!obj->parent) {
gchar *name = g_strdup_printf("device[%d]", unattached_count++);
object_property_add_child(container_get(qdev_get_machine(),
On Wed, Jan 12, 2022 at 11:55:17AM -0500, Yang Zhong wrote: > When Libvirt start, it get the vcpu's unavailable-features from > /machine/unattached/device[0] path by qom-get command, but in SGX > guest, since the sgx-epc virtual device is initialized before VCPU > creation(virtual sgx need set the virtual EPC info in the cpuid). This > /machine/unattached/device[0] is occupied by sgx-epc device, which > fail to get the unvailable-features from /machine/unattached/device[0]. If libvirt decides to enable SGX in a VM, then surely it knows that it should just query /machine/unattached/device[1] to get the CPU features instead. Why do we need to do anything in QEMU ? > > This patch make one new /machine/sgx object to avoid this issue. > (qemu) qom-list /machine/unattached/ > device[0] (child<host-x86_64-cpu>) > > (qemu) qom-list /machine/sgx > device[0] (child<sgx-epc>) > > Signed-off-by: Yang Zhong <yang.zhong@intel.com> > --- > hw/core/qdev.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/hw/core/qdev.c b/hw/core/qdev.c > index 84f3019440..4154eef0d8 100644 > --- a/hw/core/qdev.c > +++ b/hw/core/qdev.c > @@ -497,7 +497,7 @@ static void device_set_realized(Object *obj, bool value, Error **errp) > NamedClockList *ncl; > Error *local_err = NULL; > bool unattached_parent = false; > - static int unattached_count; > + static int unattached_count, sgx_count; > > if (dev->hotplugged && !dc->hotpluggable) { > error_setg(errp, QERR_DEVICE_NO_HOTPLUG, object_get_typename(obj)); > @@ -509,7 +509,15 @@ static void device_set_realized(Object *obj, bool value, Error **errp) > goto fail; > } > > - if (!obj->parent) { > + if (!obj->parent && !strcmp(object_get_typename(obj), "sgx-epc")) { > + gchar *name = g_strdup_printf("device[%d]", sgx_count++); > + > + object_property_add_child(container_get(qdev_get_machine(), > + "/sgx"), > + name, obj); > + unattached_parent = true; > + g_free(name); The qdev.c file is part of our generic object code. It should not contain any code that is tied to very specific object types like this. > + } else if (!obj->parent) { > gchar *name = g_strdup_printf("device[%d]", unattached_count++); > > object_property_add_child(container_get(qdev_get_machine(), Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
On Wed, 12 Jan 2022 at 10:14, Daniel P. Berrangé <berrange@redhat.com> wrote: > > On Wed, Jan 12, 2022 at 11:55:17AM -0500, Yang Zhong wrote: > > When Libvirt start, it get the vcpu's unavailable-features from > > /machine/unattached/device[0] path by qom-get command, but in SGX > > guest, since the sgx-epc virtual device is initialized before VCPU > > creation(virtual sgx need set the virtual EPC info in the cpuid). This > > /machine/unattached/device[0] is occupied by sgx-epc device, which > > fail to get the unvailable-features from /machine/unattached/device[0]. > > If libvirt decides to enable SGX in a VM, then surely it knows > that it should just query /machine/unattached/device[1] to get > the CPU features instead. Why do we need to do anything in QEMU ? libvirt having to know it needs to look at /machine/unattached/device[n] for anything is a bit fragile, really... it's effectively encoding knowledge about what order things happen to get created inside QEMU. -- PMM
On Wed, Jan 12, 2022 at 10:16:33AM +0000, Peter Maydell wrote: > On Wed, 12 Jan 2022 at 10:14, Daniel P. Berrangé <berrange@redhat.com> wrote: > > > > On Wed, Jan 12, 2022 at 11:55:17AM -0500, Yang Zhong wrote: > > > When Libvirt start, it get the vcpu's unavailable-features from > > > /machine/unattached/device[0] path by qom-get command, but in SGX > > > guest, since the sgx-epc virtual device is initialized before VCPU > > > creation(virtual sgx need set the virtual EPC info in the cpuid). This > > > /machine/unattached/device[0] is occupied by sgx-epc device, which > > > fail to get the unvailable-features from /machine/unattached/device[0]. > > > > If libvirt decides to enable SGX in a VM, then surely it knows > > that it should just query /machine/unattached/device[1] to get > > the CPU features instead. Why do we need to do anything in QEMU ? > > libvirt having to know it needs to look at /machine/unattached/device[n] > for anything is a bit fragile, really... it's effectively encoding > knowledge about what order things happen to get created inside QEMU. So how do CPUs and other devices end up being under /unattached/ ? Can we ensure that *all* QEMU devices have a well defined attachment point ? Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
Hi Daniel, On Wed, Jan 12, 2022 at 10:11:35AM +0000, Daniel P. Berrangé wrote: > On Wed, Jan 12, 2022 at 11:55:17AM -0500, Yang Zhong wrote: > > When Libvirt start, it get the vcpu's unavailable-features from > > /machine/unattached/device[0] path by qom-get command, but in SGX > > guest, since the sgx-epc virtual device is initialized before VCPU > > creation(virtual sgx need set the virtual EPC info in the cpuid). This > > /machine/unattached/device[0] is occupied by sgx-epc device, which > > fail to get the unvailable-features from /machine/unattached/device[0]. > > If libvirt decides to enable SGX in a VM, then surely it knows > that it should just query /machine/unattached/device[1] to get > the CPU features instead. Why do we need to do anything in QEMU ? > I listed two solutions in the Qemu or Libvirt before: https://lists.nongnu.org/archive/html/qemu-devel/2021-11/msg05670.html This time, I posted this patch and hope to have a talk for this issue. If Libvirt side should handle this, I will drop this patch and inform them to do this. Thanks! > > > > This patch make one new /machine/sgx object to avoid this issue. > > (qemu) qom-list /machine/unattached/ > > device[0] (child<host-x86_64-cpu>) > > > > (qemu) qom-list /machine/sgx > > device[0] (child<sgx-epc>) > > > > Signed-off-by: Yang Zhong <yang.zhong@intel.com> > > --- > > hw/core/qdev.c | 12 ++++++++++-- > > 1 file changed, 10 insertions(+), 2 deletions(-) > > > > diff --git a/hw/core/qdev.c b/hw/core/qdev.c > > index 84f3019440..4154eef0d8 100644 > > --- a/hw/core/qdev.c > > +++ b/hw/core/qdev.c > > @@ -497,7 +497,7 @@ static void device_set_realized(Object *obj, bool value, Error **errp) > > NamedClockList *ncl; > > Error *local_err = NULL; > > bool unattached_parent = false; > > - static int unattached_count; > > + static int unattached_count, sgx_count; > > > > if (dev->hotplugged && !dc->hotpluggable) { > > error_setg(errp, QERR_DEVICE_NO_HOTPLUG, object_get_typename(obj)); > > @@ -509,7 +509,15 @@ static void device_set_realized(Object *obj, bool value, Error **errp) > > goto fail; > > } > > > > - if (!obj->parent) { > > + if (!obj->parent && !strcmp(object_get_typename(obj), "sgx-epc")) { > > + gchar *name = g_strdup_printf("device[%d]", sgx_count++); > > + > > + object_property_add_child(container_get(qdev_get_machine(), > > + "/sgx"), > > + name, obj); > > + unattached_parent = true; > > + g_free(name); > > The qdev.c file is part of our generic object code. It should not > contain any code that is tied to very specific object types like > this. Okay, thanks! Yang > > > + } else if (!obj->parent) { > > gchar *name = g_strdup_printf("device[%d]", unattached_count++); > > > > object_property_add_child(container_get(qdev_get_machine(), > > Regards, > Daniel > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
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