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(-)
