Comment 23 for bug 2009048

Verification done on focal.

...

$ lsb_release -cs
focal

$ grep 'AMD EPYC' /proc/cpuinfo
model name : AMD EPYC Processor

$ lspci | grep -i iommu
00:02.0 IOMMU: Advanced Micro Devices, Inc. [AMD] Device 0010

...

Before:
---

$ dpkg -s qemu-system-x86 | grep Version:
Version: 1:4.2-3ubuntu6.24

$ sudo qemu-system-x86_64 -nographic -device vfio-pci,host=$PCI -m 1035265
qemu-system-x86_64: -device vfio-pci,host=0000:00:03.0: VFIO_MAP_DMA: -22
qemu-system-x86_64: -device vfio-pci,host=0000:00:03.0: vfio 0000:00:03.0: failed to setup container for group 2: memory listener initialization failed: Region pc.ram: vfio_dma_map(0x561a25890a70, 0x100000000, 0xfc00100000, 0x7e7e7fe00000) = -22 (Invalid argument)

$ sudo qemu-system-x86_64 -nographic -device vfio-pci,host=$PCI -m 1035264
[ 197.849263] Out of memory: Killed process 4968 (qemu-system-x86) total-vm:1062539320kB, anon-rss:3787224kB, file-rss:2624kB, shmem-rss:0kB, UID:0 pgtables:7600kB oom_score_adj:0
Killed

After:
---

$ sudo add-apt-repository -y 'deb http://archive.ubuntu.com/ubuntu focal-proposed main'
$ sudo apt install -y qemu-system-x86

$ dpkg -s qemu-system-x86 | grep Version:
Version: 1:4.2-3ubuntu6.25

$ sudo qemu-system-x86_64 -nographic -device vfio-pci,host=$PCI -m 1035265
qemu-system-x86_64: -device vfio-pci,host=0000:00:03.0: VFIO_MAP_DMA: -22 (hint: AMD IOMMU: reduce VM ram)
qemu-system-x86_64: -device vfio-pci,host=0000:00:03.0: vfio 0000:00:03.0: failed to setup container for group 2: memory listener initialization failed: Region pc.ram: vfio_dma_map(0x5605ab3aea70, 0x100000000, 0xfc00100000, 0x7e79cbe00000) = -22 (Invalid argument)

$ sudo qemu-system-x86_64 -nographic -device vfio-pci,host=$PCI -m 1035264
[ 313.558785] Out of memory: Killed process 5747 (qemu-system-x86) total-vm:1062539320kB, anon-rss:3797352kB, file-rss:2668kB, shmem-rss:0kB, UID:0 pgtables:7616kB oom_score_adj:0
Killed