On 5/2/2025 7:45 AM, Alejandro Jimenez wrote:
This series adds support for guests using the AMD vIOMMU to enable DMA
remapping for VFIO devices. In addition to the currently supported
passthrough (PT) mode, guest kernels are now able to to provide DMA
address translation and access permission checking to VFs attached to
paging domains, using the AMD v1 I/O page table format.
Please see v1[0] cover letter for additional details such as example
QEMU command line parameters used in testing.
Changes since v1[0]:
- Added documentation entry for '-device amd-iommu'
- Code movement with no functional changes to avoid use of forward
declarations in later patches [Sairaj, mst]
- Moved addr_translation and dma-remap property to separate commits.
The dma-remap feature is only available for users to enable after
all required functionality is implemented [Sairaj]
- Explicit initialization of significant fields like addr_translation
and notifier_flags [Sairaj]
- Fixed bug in decoding of invalidation size [Sairaj]
- Changed fetch_pte() to use an out parameter for pte, and be able to
check for error conditions via negative return value [Clement]
- Removed UNMAP-only notifier optimization, leaving vhost support for
later series [Sairaj]
- Fixed ordering between address space unmap and memory region activation
on devtab invalidation [Sairaj]
- Fixed commit message with "V=1, TV=0" [Sairaj]
- Dropped patch removing the page_fault event. That area is better
addressed in separate series.
- Independent testing by Sairaj (thank you!)
Thank you,
Alejandro
[0]
https://lore.kernel.org/all/20250414020253.443831-1-alejandro.j.jime...@oracle.com/
Alejandro Jimenez (20):
memory: Adjust event ranges to fit within notifier boundaries
amd_iommu: Document '-device amd-iommu' common options
amd_iommu: Reorder device and page table helpers
amd_iommu: Helper to decode size of page invalidation command
amd_iommu: Add helper function to extract the DTE
amd_iommu: Return an error when unable to read PTE from guest memory
amd_iommu: Add helpers to walk AMD v1 Page Table format
amd_iommu: Add a page walker to sync shadow page tables on
invalidation
amd_iommu: Add basic structure to support IOMMU notifier updates
amd_iommu: Sync shadow page tables on page invalidation
amd_iommu: Use iova_tree records to determine large page size on UNMAP
amd_iommu: Unmap all address spaces under the AMD IOMMU on reset
amd_iommu: Add replay callback
amd_iommu: Invalidate address translations on INVALIDATE_IOMMU_ALL
amd_iommu: Toggle memory regions based on address translation mode
amd_iommu: Set all address spaces to default translation mode on reset
amd_iommu: Add dma-remap property to AMD vIOMMU device
amd_iommu: Toggle address translation mode on devtab entry
invalidation
amd_iommu: Do not assume passthrough translation when DTE[TV]=0
amd_iommu: Refactor amdvi_page_walk() to use common code for page walk
hw/i386/amd_iommu.c | 1005 ++++++++++++++++++++++++++++++++++++-------
hw/i386/amd_iommu.h | 52 +++
qemu-options.hx | 23 +
system/memory.c | 10 +-
4 files changed, 934 insertions(+), 156 deletions(-)
base-commit: 5134cf9b5d3aee4475fe7e1c1c11b093731073cf
Hi Alejandro,
Tested the v2, everything looks good when I boot guest with upstream
kernel. But I observed that NVME driver fails to load with guest kernel
version 4.15.0-213-generic. This is the default kernel that comes with
the ubuntu image.
This is what I see in the dmesg
[ 26.702381] nvme nvme0: pci function 0000:00:04.0
[ 26.817847] nvme nvme0: missing or invalid SUBNQN field.
I am using following command qemu command line
-enable-kvm -m 10G -smp cpus=$NUM_VCPUS \
-device amd-iommu,dma-remap=on \
-netdev user,id=USER0,hostfwd=tcp::3333-:22 \
-device
virtio-net-pci,id=vnet0,iommu_platform=on,disable-legacy=on,romfile=,netdev=USER0
\
-cpu
EPYC-Genoa,x2apic=on,kvm-msi-ext-dest-id=on,+kvm-pv-unhalt,kvm-pv-tlb-flush,kvm-pv-ipi,kvm-pv-sched-yield
\
-name guest=my-vm,debug-threads=on \
-machine q35,kernel_irqchip=split \
-global kvm-pit.lost_tick_policy=discard \
-nographic -vga none -chardev stdio,id=STDIO0,signal=off,mux=on \
-device isa-serial,id=isa-serial0,chardev=STDIO0 \
-smbios type=0,version=2.8 \
-blockdev
node-name=drive0,driver=qcow2,file.driver=file,file.filename=$IMG \
-device virtio-blk-pci,num-queues=8,drive=drive0 \
-chardev socket,id=SOCKET1,server=on,wait=off,path=qemu.mon.user3333 \
-mon chardev=SOCKET1,mode=control \
-device vfio-pci,host=0000:44:00.0
Do you have any idea what might trigger this.
I see the error only when I am using emulated AMD IOMMU with passthrough
device. Regular passthrough works fine.
Regards
Sairaj Kodilkar
P.S. I know that the guest kernel is quite old but still wanted to make
you aware.
