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

[Alejandro Jimenez <alejandro.j.jimenez@oracle.com>]

On 10/8/25 12:43 PM, Sairaj Kodilkar wrote:
> This series provide fixes for following two issues:
> 

I was able to reproduce and confirm the fixes for the issues you list. 
Please see my replies to the individual patches for my suggestions.

> 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
> 
> Base commit: (qemu uptream) eb7abb4a719f
> 

General feedback for both patches:

I know the commit log is not consistent so far, but going forward I 
propose we adopt the shorter prefix "amd_iommu: " for commit summaries. 
There is no ambiguity (only one arch has amd_iommu), so the full path is 
not required (i.e. avoid 'hw/i386/amd_iommu: '). Shorter boilerplate 
leaves more space for relevant details, and helps people like me who 
struggle to comply with character limits :).

Thank you,
Alejandro

> Sairaj Kodilkar (2):
>    hw/i386/amd_iommu: Fix handling device on buses != 0
>    hw/i386/amd_iommu: Support 64 bit address for IOTLB lookup
> 
>   hw/i386/amd_iommu.c | 166 +++++++++++++++++++++++++++-----------------
>   hw/i386/amd_iommu.h |   7 +-
>   2 files changed, 106 insertions(+), 67 deletions(-)
>