Comment 3 for bug 1887218

Since the workaround involves amd's iommu and kernel 5.5, we may be able to find a patch that fixes this by cherry-pikcy: git log --pretty=short v5.4..v5.5 -- drivers/iommu/amd_iommu.c

commit 1daa56bcfd8b329447e0c1b1e91c3925d08489b7
Merge: a5255bc31673 9b3a713feef8
Author: Linus Torvalds <email address hidden>

    Merge tag 'iommu-updates-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu

commit 995e2ef08280dab8de6c517acd836613678fe2a3
Merge: 1fca7e0e6fe6 ae5e6c6439c3 cb0701acfa7e b5b42b24d783 2e127203d116
Author: Rafael J. Wysocki <email address hidden>

    Merge branches 'acpi-utils', 'acpi-platform', 'acpi-video' and 'acpi-doc'

commit 9b3a713feef8db41d4bcccb3b97e86ee906690c8
Merge: 4e7120d79edb da6b05dce2a9 1289f7f15001 5b47748ecf2e c90ae4a63541 96d3ab802e49 34d1b0895dbd 3c124435e8dd 6c3a44ed3c55 c1c8058dfb98 808be0aae53a
Author: Joerg Roedel <email address hidden>

    Merge branches 'iommu/fixes', 'arm/qcom', 'arm/renesas', 'arm/rockchip', 'arm/mediatek', 'arm/tegra', 'arm/smmu', 'x86/amd', 'x86/vt-d', 'virtio' and 'core' into next

commit 3c124435e8dd516df4b2fc983f4415386fd6edae
Author: Logan Gunthorpe <email address hidden>

    iommu/amd: Support multiple PCI DMA aliases in IRQ Remapping

commit 3332364e4ebc0581d133a334645a20fd13b580f1
Author: Logan Gunthorpe <email address hidden>

    iommu/amd: Support multiple PCI DMA aliases in device table

commit a5bbbf37c6f8522a1afd46c37b5a0d1ce63232b7
Author: Denys Vlasenko <email address hidden>

    iommu/amd: Do not re-fetch iommu->cmd_buf_tail

commit 3057fb9377eb5e73386dd0d8804bf72bdd23e391
Author: Joerg Roedel <email address hidden>

    iommu/amd: Pass gfp flags to iommu_map_page() in amd_iommu_map()

commit 470eb3b31134ada545dcb41e94a0c97b42c95803
Author: Suthikulpanit, Suravee <email address hidden>

    iommu/amd: Simpify decoding logic for INVALID_PPR_REQUEST event

commit ae5e6c6439c3d0ac8e9c71523790ba1ff6887894
Author: Andy Shevchenko <email address hidden>

    iommu/amd: Switch to use acpi_dev_hid_uid_match()

commit be62dbf554c5b50718a54a359372c148cd9975c7
Author: Tom Murphy <email address hidden>

    iommu/amd: Convert AMD iommu driver to the dma-iommu api

commit 781ca2de89bae1b1d2c96df9ef33e9a324415995
Author: Tom Murphy <email address hidden>

    iommu: Add gfp parameter to iommu_ops::map

commit 37ec8eb851c1876580a963f283fe7496592b9f72
Author: Tom Murphy <email address hidden>

    iommu/amd: Remove unnecessary locking from AMD iommu driver