pci: Only unmap bus_master_enabled_region if was added previously

[Qemu-devel] [PATCH qemu] pci: Only unmap bus_master_enabled_region if was added previously

Posted by Alexey Kardashevskiy 7 years ago

Normally pci_init_bus_master() would be called either via
bus->machine_done.notify or directly from do_pci_register_device().

However if a device's realize() failed, pci_init_bus_master() is not
called, and do_pci_unregister_device() fails on
memory_region_del_subregion() as it was not mapped.

This adds a check that subregion was mapped before unmapping it.

Fixes: c53598ed18e4 ("pci: Add missing drop of bus master AS reference")
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
This is to pass iotest 051 which does run QEMU like this:

ppc64-softmmu/qemu-system-ppc64 -nodefaults -machine accel=qtest -nographic -monitor stdio -serial none -drive if=virtio

which normally fails with:

qemu-system-ppc64: -drive if=virtio: Device needs media, but drive is empty

or asserts (without this patch):

qemu-system-ppc64: /home/aik/p/qemu-kvm/memory.c:2118: memory_region_del_subregion: Assertion `subregion->container == mr' failed.
---
 hw/pci/pci.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index bd8043c460..259483b1c0 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -869,8 +869,10 @@ static void do_pci_unregister_device(PCIDevice *pci_dev)
     pci_dev->bus->devices[pci_dev->devfn] = NULL;
     pci_config_free(pci_dev);
 
-    memory_region_del_subregion(&pci_dev->bus_master_container_region,
-                                &pci_dev->bus_master_enable_region);
+    if (memory_region_is_mapped(&pci_dev->bus_master_enable_region)) {
+        memory_region_del_subregion(&pci_dev->bus_master_container_region,
+                                    &pci_dev->bus_master_enable_region);
+    }
     address_space_destroy(&pci_dev->bus_master_as);
 }
 
-- 
2.11.0

Re: [Qemu-devel] [PATCH qemu] pci: Only unmap bus_master_enabled_region if was added previously

Posted by Max Reitz 7 years ago

On 31.03.2017 06:47, Alexey Kardashevskiy wrote:
> Normally pci_init_bus_master() would be called either via
> bus->machine_done.notify or directly from do_pci_register_device().
> 
> However if a device's realize() failed, pci_init_bus_master() is not
> called, and do_pci_unregister_device() fails on
> memory_region_del_subregion() as it was not mapped.
> 
> This adds a check that subregion was mapped before unmapping it.
> 
> Fixes: c53598ed18e4 ("pci: Add missing drop of bus master AS reference")
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
> This is to pass iotest 051 which does run QEMU like this:
> 
> ppc64-softmmu/qemu-system-ppc64 -nodefaults -machine accel=qtest -nographic -monitor stdio -serial none -drive if=virtio
> 
> which normally fails with:
> 
> qemu-system-ppc64: -drive if=virtio: Device needs media, but drive is empty
> 
> or asserts (without this patch):
> 
> qemu-system-ppc64: /home/aik/p/qemu-kvm/memory.c:2118: memory_region_del_subregion: Assertion `subregion->container == mr' failed.
> ---
>  hw/pci/pci.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index bd8043c460..259483b1c0 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -869,8 +869,10 @@ static void do_pci_unregister_device(PCIDevice *pci_dev)
>      pci_dev->bus->devices[pci_dev->devfn] = NULL;
>      pci_config_free(pci_dev);
>  
> -    memory_region_del_subregion(&pci_dev->bus_master_container_region,
> -                                &pci_dev->bus_master_enable_region);
> +    if (memory_region_is_mapped(&pci_dev->bus_master_enable_region)) {
> +        memory_region_del_subregion(&pci_dev->bus_master_container_region,
> +                                    &pci_dev->bus_master_enable_region);
> +    }
>      address_space_destroy(&pci_dev->bus_master_as);
>  }

I'm not sure whether it's generally assumed to be safe to call
memory_region_is_mapped() on "uninitialized" memory regions
(bus_master_enable_region is just completely zeroed out before
pci_init_bus_master(), as far as I can see and guess), but it certainly
works in practice, so:

Reviewed-by: Max Reitz <mreitz@redhat.com>

Re: [Qemu-devel] [PATCH qemu] pci: Only unmap bus_master_enabled_region if was added previously

Posted by Alexey Kardashevskiy 7 years ago

On 31/03/17 21:33, Max Reitz wrote:
> On 31.03.2017 06:47, Alexey Kardashevskiy wrote:
>> Normally pci_init_bus_master() would be called either via
>> bus->machine_done.notify or directly from do_pci_register_device().
>>
>> However if a device's realize() failed, pci_init_bus_master() is not
>> called, and do_pci_unregister_device() fails on
>> memory_region_del_subregion() as it was not mapped.
>>
>> This adds a check that subregion was mapped before unmapping it.
>>
>> Fixes: c53598ed18e4 ("pci: Add missing drop of bus master AS reference")
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> ---
>> This is to pass iotest 051 which does run QEMU like this:
>>
>> ppc64-softmmu/qemu-system-ppc64 -nodefaults -machine accel=qtest -nographic -monitor stdio -serial none -drive if=virtio
>>
>> which normally fails with:
>>
>> qemu-system-ppc64: -drive if=virtio: Device needs media, but drive is empty
>>
>> or asserts (without this patch):
>>
>> qemu-system-ppc64: /home/aik/p/qemu-kvm/memory.c:2118: memory_region_del_subregion: Assertion `subregion->container == mr' failed.
>> ---
>>  hw/pci/pci.c | 6 ++++--
>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
>> index bd8043c460..259483b1c0 100644
>> --- a/hw/pci/pci.c
>> +++ b/hw/pci/pci.c
>> @@ -869,8 +869,10 @@ static void do_pci_unregister_device(PCIDevice *pci_dev)
>>      pci_dev->bus->devices[pci_dev->devfn] = NULL;
>>      pci_config_free(pci_dev);
>>  
>> -    memory_region_del_subregion(&pci_dev->bus_master_container_region,
>> -                                &pci_dev->bus_master_enable_region);
>> +    if (memory_region_is_mapped(&pci_dev->bus_master_enable_region)) {
>> +        memory_region_del_subregion(&pci_dev->bus_master_container_region,
>> +                                    &pci_dev->bus_master_enable_region);
>> +    }
>>      address_space_destroy(&pci_dev->bus_master_as);
>>  }
> 
> I'm not sure whether it's generally assumed to be safe to call
> memory_region_is_mapped() on "uninitialized" memory regions
> (bus_master_enable_region is just completely zeroed out before
> pci_init_bus_master(), as far as I can see and guess), but it certainly
> works in practice, so:
> 
> Reviewed-by: Max Reitz <mreitz@redhat.com>


PCI device is also initialized via object_initialize() which does memset(0)
so I assume it is quite safe.


-- 
Alexey

Re: [Qemu-devel] [PATCH qemu] pci: Only unmap bus_master_enabled_region if was added previously

Posted by Marcel Apfelbaum 7 years ago

On 03/31/2017 07:47 AM, Alexey Kardashevskiy wrote:
> Normally pci_init_bus_master() would be called either via
> bus->machine_done.notify or directly from do_pci_register_device().
>
> However if a device's realize() failed, pci_init_bus_master() is not
> called, and do_pci_unregister_device() fails on
> memory_region_del_subregion() as it was not mapped.
>
> This adds a check that subregion was mapped before unmapping it.
>
> Fixes: c53598ed18e4 ("pci: Add missing drop of bus master AS reference")
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
> This is to pass iotest 051 which does run QEMU like this:
>
> ppc64-softmmu/qemu-system-ppc64 -nodefaults -machine accel=qtest -nographic -monitor stdio -serial none -drive if=virtio
>
> which normally fails with:
>
> qemu-system-ppc64: -drive if=virtio: Device needs media, but drive is empty
>
> or asserts (without this patch):
>
> qemu-system-ppc64: /home/aik/p/qemu-kvm/memory.c:2118: memory_region_del_subregion: Assertion `subregion->container == mr' failed.
> ---
>  hw/pci/pci.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index bd8043c460..259483b1c0 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -869,8 +869,10 @@ static void do_pci_unregister_device(PCIDevice *pci_dev)
>      pci_dev->bus->devices[pci_dev->devfn] = NULL;
>      pci_config_free(pci_dev);
>
> -    memory_region_del_subregion(&pci_dev->bus_master_container_region,
> -                                &pci_dev->bus_master_enable_region);
> +    if (memory_region_is_mapped(&pci_dev->bus_master_enable_region)) {
> +        memory_region_del_subregion(&pci_dev->bus_master_container_region,
> +                                    &pci_dev->bus_master_enable_region);
> +    }
>      address_space_destroy(&pci_dev->bus_master_as);
>  }
>
>

Hi,

Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>

Thanks,
Marcel

Re: [Qemu-devel] [PATCH qemu] pci: Only unmap bus_master_enabled_region if was added previously

Posted by John Snow 7 years ago


On 03/31/2017 12:47 AM, Alexey Kardashevskiy wrote:
> Normally pci_init_bus_master() would be called either via
> bus->machine_done.notify or directly from do_pci_register_device().
> 
> However if a device's realize() failed, pci_init_bus_master() is not
> called, and do_pci_unregister_device() fails on
> memory_region_del_subregion() as it was not mapped.
> 
> This adds a check that subregion was mapped before unmapping it.
> 
> Fixes: c53598ed18e4 ("pci: Add missing drop of bus master AS reference")
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
> This is to pass iotest 051 which does run QEMU like this:
> 
> ppc64-softmmu/qemu-system-ppc64 -nodefaults -machine accel=qtest -nographic -monitor stdio -serial none -drive if=virtio
> 
> which normally fails with:
> 
> qemu-system-ppc64: -drive if=virtio: Device needs media, but drive is empty
> 
> or asserts (without this patch):
> 
> qemu-system-ppc64: /home/aik/p/qemu-kvm/memory.c:2118: memory_region_del_subregion: Assertion `subregion->container == mr' failed.
> ---
>  hw/pci/pci.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index bd8043c460..259483b1c0 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -869,8 +869,10 @@ static void do_pci_unregister_device(PCIDevice *pci_dev)
>      pci_dev->bus->devices[pci_dev->devfn] = NULL;
>      pci_config_free(pci_dev);
>  
> -    memory_region_del_subregion(&pci_dev->bus_master_container_region,
> -                                &pci_dev->bus_master_enable_region);
> +    if (memory_region_is_mapped(&pci_dev->bus_master_enable_region)) {
> +        memory_region_del_subregion(&pci_dev->bus_master_container_region,
> +                                    &pci_dev->bus_master_enable_region);
> +    }
>      address_space_destroy(&pci_dev->bus_master_as);
>  }
>  
> 

Thanks for the quick turnaround!

Tested-by: John Snow <jsnow@redhat.com>

Re: [Qemu-devel] [PATCH qemu] pci: Only unmap bus_master_enabled_region if was added previously

Posted by Paolo Bonzini 7 years ago

> On 03/31/2017 12:47 AM, Alexey Kardashevskiy wrote:
> > Normally pci_init_bus_master() would be called either via
> > bus->machine_done.notify or directly from do_pci_register_device().
> > 
> > However if a device's realize() failed, pci_init_bus_master() is not
> > called, and do_pci_unregister_device() fails on
> > memory_region_del_subregion() as it was not mapped.
> > 
> > This adds a check that subregion was mapped before unmapping it.
> > 
> > Fixes: c53598ed18e4 ("pci: Add missing drop of bus master AS reference")
> > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> > ---
> > This is to pass iotest 051 which does run QEMU like this:
> > 
> > ppc64-softmmu/qemu-system-ppc64 -nodefaults -machine accel=qtest -nographic
> > -monitor stdio -serial none -drive if=virtio
> > 
> > which normally fails with:
> > 
> > qemu-system-ppc64: -drive if=virtio: Device needs media, but drive is empty
> > 
> > or asserts (without this patch):
> > 
> > qemu-system-ppc64: /home/aik/p/qemu-kvm/memory.c:2118:
> > memory_region_del_subregion: Assertion `subregion->container == mr'
> > failed.
> > ---
> >  hw/pci/pci.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > index bd8043c460..259483b1c0 100644
> > --- a/hw/pci/pci.c
> > +++ b/hw/pci/pci.c
> > @@ -869,8 +869,10 @@ static void do_pci_unregister_device(PCIDevice
> > *pci_dev)
> >      pci_dev->bus->devices[pci_dev->devfn] = NULL;
> >      pci_config_free(pci_dev);
> >  
> > -    memory_region_del_subregion(&pci_dev->bus_master_container_region,
> > -                                &pci_dev->bus_master_enable_region);
> > +    if (memory_region_is_mapped(&pci_dev->bus_master_enable_region)) {
> > +        memory_region_del_subregion(&pci_dev->bus_master_container_region,
> > +                                    &pci_dev->bus_master_enable_region);
> > +    }
> >      address_space_destroy(&pci_dev->bus_master_as);
> >  }
> >  
> > 
> 
> Thanks for the quick turnaround!
> 
> Tested-by: John Snow <jsnow@redhat.com>

Acked-by: Paolo Bonzini <pbonzini@redhat.com>

Re: [Qemu-devel] [PATCH qemu] pci: Only unmap bus_master_enabled_region if was added previously

Posted by Michael S. Tsirkin 7 years ago

On Fri, Mar 31, 2017 at 03:47:11PM +1100, Alexey Kardashevskiy wrote:
> Normally pci_init_bus_master() would be called either via
> bus->machine_done.notify or directly from do_pci_register_device().
> 
> However if a device's realize() failed, pci_init_bus_master() is not
> called, and do_pci_unregister_device() fails on
> memory_region_del_subregion() as it was not mapped.
> 
> This adds a check that subregion was mapped before unmapping it.
> 
> Fixes: c53598ed18e4 ("pci: Add missing drop of bus master AS reference")
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Applied, thanks everyone.

> ---
> This is to pass iotest 051 which does run QEMU like this:
> 
> ppc64-softmmu/qemu-system-ppc64 -nodefaults -machine accel=qtest -nographic -monitor stdio -serial none -drive if=virtio
> 
> which normally fails with:
> 
> qemu-system-ppc64: -drive if=virtio: Device needs media, but drive is empty
> 
> or asserts (without this patch):
> 
> qemu-system-ppc64: /home/aik/p/qemu-kvm/memory.c:2118: memory_region_del_subregion: Assertion `subregion->container == mr' failed.
> ---
>  hw/pci/pci.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index bd8043c460..259483b1c0 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -869,8 +869,10 @@ static void do_pci_unregister_device(PCIDevice *pci_dev)
>      pci_dev->bus->devices[pci_dev->devfn] = NULL;
>      pci_config_free(pci_dev);
>  
> -    memory_region_del_subregion(&pci_dev->bus_master_container_region,
> -                                &pci_dev->bus_master_enable_region);
> +    if (memory_region_is_mapped(&pci_dev->bus_master_enable_region)) {
> +        memory_region_del_subregion(&pci_dev->bus_master_container_region,
> +                                    &pci_dev->bus_master_enable_region);
> +    }
>      address_space_destroy(&pci_dev->bus_master_as);
>  }
>  
> -- 
> 2.11.0