Re: [PATCH v3 0/2] amd_iommu: Cleanups and fixes (PART 2)

[Vasant Hegde <vasant.hegde@amd.com>]

Alejandro,

On 10/19/2025 10:12 PM, Alejandro Jimenez wrote:
> Hi Sairaj,
> 
> On 10/17/25 2:13 AM, Sairaj Kodilkar wrote:
>> This series provide fixes for following two issues:
>>
>> 1. AMD IOMMU fails to detect the devices when they are attached to PCI bus with
>>     bus id != 0.
>>     e.g. With following command line, dhclient command fails inside the guest
>>
>>      -device pcie-root-
>> port,port=0x10,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,addr=0x5 \
>>      -netdev user,id=USER0,hostfwd=tcp::3333-:22 \
>>      -device virtio-net-pci,id=vnet0,iommu_platform=on,disable-
>> legacy=on,romfile=,netdev=USER0,bus=pci.1,addr=0 \
>>
>> 2. Current AMD IOMMU supports IOVAs upto 60 bit which cause failure while
>>     setting up the devices when guest is booted with command line
>>     "iommu.forcedac=1".
>>
>>     One example of the failure is when there are two virtio ethernet devices
>>     attached to the guest with command line
>>             -netdev user,id=USER0 \
>>         -netdev user,id=USER1 \
>>         -device virtio-net-pci,id=vnet0,iommu_platform=on,disable-
>> legacy=on,romfile=,netdev=USER0 \
>>         -device virtio-net-pci,id=vnet1,iommu_platform=on,disable-
>> legacy=on,romfile=,netdev=USER1 \
>>         In this case dhclient fails for second device with following dmesg
>>         [   24.802644] virtio_net virtio0 enp0s1: TX timeout on queue: 0, sq:
>> output.0, vq: 0x1, name: output.0, 5664000 usecs ago
>>     [   29.856716] virtio_net virtio0 enp0s1: NETDEV WATCHDOG: CPU: 59:
>> transmit queue 0 timed out 10720 ms
>>     [   29.858585] virtio_net virtio0 enp0s1: TX timeout on queue: 0, sq:
>> output.0, vq: 0x1, name: output.0, 10720000 usecs ago
>>
> 
> Besides the above issues, I can also confirm that in combination with a patched
> VFIO driver in the host kernel, this series addresses the problems I mentioned
> earlier with VFIO passthrough devices + DMA remap mode + forcedac=1 on guest
> reboot. Thank you!

Nice!  Thanks for verifying.


-Vasant

> 
> For the series:
> Reviewed-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
> Tested-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
> 
> 
>> -------------------------------------------------------------------------------
>>
>> Change log:
>> ----------
>>
>> * Changes since V2:
>> https://lore.kernel.org/qemu-devel/20251013050046.393-1-sarunkod@amd.com/
>> P1:
>>   - Remove cast from the pointer assignment [MST]
>>   - Rename struct amdvi_as_key to AMDViAsKey [Alejandro, MST]
>>   - Fix compilation error due to missing 'static' [Alejandro]
>>
>> P2:
>>   - Rename struct amdvi_iotlb_key to AMDViIOTLBKey [Alejandro, MST]
>>   - Fix compilation error [Alejandro]
>>
>>
>> * Changes Since V1:
>> https://lore.kernel.org/qemu-devel/20251008164324.21553-1-sarunkod@amd.com/
>> P1:
>>   - Use fixed type uint8_t for devfn
>>   - Use uintptr_t instead of uint64_t
>>   - Build hash key using lower 56 bits of bus pointer and 8 bits of devfn
>>   - Use gboolean instead of int for amdvi_find_as_by_devid
>>   - Update comments
>>   - Use IOMMU_NOTIFIER_NONE instead of IOMMU_NONE
>>
>> P2:
>>   - Reword commit message
>>   - Correctly initialize `struct amdvi_iotlb_key`
>>   - Remove unused macro
>>
>> -------------------------------------------------------------------------------
>>
>> Base commit: (qemu uptream) eb7abb4a719f
>>
>> -------------------------------------------------------------------------------
>>
>>
>> Sairaj Kodilkar (2):
>>    amd_iommu: Fix handling device on buses != 0
>>    amd_iommu: Support 64 bit address for IOTLB lookup
>>
>>   hw/i386/amd_iommu.c | 179 +++++++++++++++++++++++++++-----------------
>>   hw/i386/amd_iommu.h |   6 +-
>>   2 files changed, 113 insertions(+), 72 deletions(-)
>>
>