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[PATCH v3 0/2] amd_iommu: Fixes

Sairaj Kodilkar posted 2 patches 7 months ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20250516100535.4980-1-sarunkod@amd.com
Maintainers: "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Eduardo Habkost <eduardo@habkost.net>
hw/i386/amd_iommu.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
[PATCH v3 0/2] amd_iommu: Fixes
Posted by Sairaj Kodilkar 7 months ago 
Fix following two issues in the amd viommu
1. The guest fails to setup the passthrough device when for following setup
   because amd iommu enables the no DMA memory region even when guest is 
   using DMA remapping mode.

    -device amd-iommu,intremap=on,xtsup=on,pt=on \
    -device vfio-pci,host=<DEVID> \

    and guest forcing DMA remap mode e.g. 'iommu.passthrough=0'

    which will cause failures from QEMU:

    qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command list buffer address
    qemu-system-x86_64: AHCI: Failed to start FIS receive engine: bad FIS receive buffer address
    qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command list buffer address
    qemu-system-x86_64: AHCI: Failed to start FIS receive engine: bad FIS receive buffer address
    qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command list buffer address


2. The guest fails to boot with xtsup=on and <= 255 vCPUs, because amd_iommu
   does not enable x2apic mode.

base commit 56c6e249b6988c1b6edc2dd34ebb0f1e570a1365 (v10.0.0-rc3)

Sairaj Kodilkar (1):
  hw/i386/amd_iommu: Fix device setup failure when PT is on.

Vasant Hegde (1):
  hw/i386/amd_iommu: Fix xtsup when vcpus < 255

 hw/i386/amd_iommu.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

-- 
2.34.1
Re: [PATCH v3 0/2] amd_iommu: Fixes
Posted by Michael Tokarev 6 months, 2 weeks ago 
On 16.05.2025 13:05, Sairaj Kodilkar wrote:
> Fix following two issues in the amd viommu
> 1. The guest fails to setup the passthrough device when for following setup
>     because amd iommu enables the no DMA memory region even when guest is
>     using DMA remapping mode.
> 
>      -device amd-iommu,intremap=on,xtsup=on,pt=on \
>      -device vfio-pci,host=<DEVID> \
> 
>      and guest forcing DMA remap mode e.g. 'iommu.passthrough=0'
> 
>      which will cause failures from QEMU:
> 
>      qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command list buffer address
>      qemu-system-x86_64: AHCI: Failed to start FIS receive engine: bad FIS receive buffer address
>      qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command list buffer address
>      qemu-system-x86_64: AHCI: Failed to start FIS receive engine: bad FIS receive buffer address
>      qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command list buffer address
> 
> 
> 2. The guest fails to boot with xtsup=on and <= 255 vCPUs, because amd_iommu
>     does not enable x2apic mode.
> 
> base commit 56c6e249b6988c1b6edc2dd34ebb0f1e570a1365 (v10.0.0-rc3)
> 
> Sairaj Kodilkar (1):
>    hw/i386/amd_iommu: Fix device setup failure when PT is on.
> 
> Vasant Hegde (1):
>    hw/i386/amd_iommu: Fix xtsup when vcpus < 255

Hi!

Is this a qemu-stable material (for 10.0.x)?

Thanks,

/mjt
Re: [PATCH v3 0/2] amd_iommu: Fixes
Posted by Sairaj Kodilkar 6 months, 1 week ago 

On 6/3/2025 2:24 AM, Michael Tokarev wrote:
> On 16.05.2025 13:05, Sairaj Kodilkar wrote:
>> Fix following two issues in the amd viommu
>> 1. The guest fails to setup the passthrough device when for following 
>> setup
>>     because amd iommu enables the no DMA memory region even when guest is
>>     using DMA remapping mode.
>>
>>      -device amd-iommu,intremap=on,xtsup=on,pt=on \
>>      -device vfio-pci,host=<DEVID> \
>>
>>      and guest forcing DMA remap mode e.g. 'iommu.passthrough=0'
>>
>>      which will cause failures from QEMU:
>>
>>      qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command 
>> list buffer address
>>      qemu-system-x86_64: AHCI: Failed to start FIS receive engine: bad 
>> FIS receive buffer address
>>      qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command 
>> list buffer address
>>      qemu-system-x86_64: AHCI: Failed to start FIS receive engine: bad 
>> FIS receive buffer address
>>      qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command 
>> list buffer address
>>
>>
>> 2. The guest fails to boot with xtsup=on and <= 255 vCPUs, because 
>> amd_iommu
>>     does not enable x2apic mode.
>>
>> base commit 56c6e249b6988c1b6edc2dd34ebb0f1e570a1365 (v10.0.0-rc3)
>>
>> Sairaj Kodilkar (1):
>>    hw/i386/amd_iommu: Fix device setup failure when PT is on.
>>
>> Vasant Hegde (1):
>>    hw/i386/amd_iommu: Fix xtsup when vcpus < 255
> 
> Hi!
> 
> Is this a qemu-stable material (for 10.0.x)?

Yes it is

Thanks
Sairaj Kodilkar
Re: [PATCH v3 0/2] amd_iommu: Fixes
Posted by Michael S. Tsirkin 7 months ago 
On Fri, May 16, 2025 at 03:35:33PM +0530, Sairaj Kodilkar wrote:
> Fix following two issues in the amd viommu
> 1. The guest fails to setup the passthrough device when for following setup
>    because amd iommu enables the no DMA memory region even when guest is 
>    using DMA remapping mode.
> 
>     -device amd-iommu,intremap=on,xtsup=on,pt=on \
>     -device vfio-pci,host=<DEVID> \
> 
>     and guest forcing DMA remap mode e.g. 'iommu.passthrough=0'
> 
>     which will cause failures from QEMU:
> 
>     qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command list buffer address
>     qemu-system-x86_64: AHCI: Failed to start FIS receive engine: bad FIS receive buffer address
>     qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command list buffer address
>     qemu-system-x86_64: AHCI: Failed to start FIS receive engine: bad FIS receive buffer address
>     qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command list buffer address
> 
> 
> 2. The guest fails to boot with xtsup=on and <= 255 vCPUs, because amd_iommu
>    does not enable x2apic mode.
> 
> base commit 56c6e249b6988c1b6edc2dd34ebb0f1e570a1365 (v10.0.0-rc3)
> 
> Sairaj Kodilkar (1):
>   hw/i386/amd_iommu: Fix device setup failure when PT is on.
> 
> Vasant Hegde (1):
>   hw/i386/amd_iommu: Fix xtsup when vcpus < 255
> 
>  hw/i386/amd_iommu.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)

changelog?

> -- 
> 2.34.1
Re: [PATCH v3 0/2] amd_iommu: Fixes
Posted by Sairaj Kodilkar 7 months ago 

On 5/16/2025 4:06 PM, Michael S. Tsirkin wrote:
> On Fri, May 16, 2025 at 03:35:33PM +0530, Sairaj Kodilkar wrote:
>> Fix following two issues in the amd viommu
>> 1. The guest fails to setup the passthrough device when for following setup
>>     because amd iommu enables the no DMA memory region even when guest is
>>     using DMA remapping mode.
>>
>>      -device amd-iommu,intremap=on,xtsup=on,pt=on \
>>      -device vfio-pci,host=<DEVID> \
>>
>>      and guest forcing DMA remap mode e.g. 'iommu.passthrough=0'
>>
>>      which will cause failures from QEMU:
>>
>>      qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command list buffer address
>>      qemu-system-x86_64: AHCI: Failed to start FIS receive engine: bad FIS receive buffer address
>>      qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command list buffer address
>>      qemu-system-x86_64: AHCI: Failed to start FIS receive engine: bad FIS receive buffer address
>>      qemu-system-x86_64: AHCI: Failed to start DMA engine: bad command list buffer address
>>
>>
>> 2. The guest fails to boot with xtsup=on and <= 255 vCPUs, because amd_iommu
>>     does not enable x2apic mode.
>>
>> base commit 56c6e249b6988c1b6edc2dd34ebb0f1e570a1365 (v10.0.0-rc3)
>>
>> Sairaj Kodilkar (1):
>>    hw/i386/amd_iommu: Fix device setup failure when PT is on.
>>
>> Vasant Hegde (1):
>>    hw/i386/amd_iommu: Fix xtsup when vcpus < 255
>>
>>   hw/i386/amd_iommu.c | 20 ++++++++++----------
>>   1 file changed, 10 insertions(+), 10 deletions(-)
> 
> changelog?
> 

Sorry I forgot to update the cover-letter (Rookie mistake).

Changes Since v2:
Patch 1: Updated commit message [mst]
Patch 2: Updated commit message [mst]
v2: 
https://lore.kernel.org/qemu-devel/20250509064526.15500-1-sarunkod@amd.com/

Changes Since v1:
Patch 1: Updated commit message [Alejandro]
Patch 2: None
v1: 
https://lore.kernel.org/qemu-devel/20250410064447.29583-1-sarunkod@amd.com/

Regards
Sairaj Kodilkar
>> -- 
>> 2.34.1
>

Patchew 2.1-devel-b67e4c2

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