This is a note to let you know that I've just added the patch titled iommu/amd: Fix legacy interrupt remapping for x2APIC-enabled system to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: iommu-amd-fix-legacy-interrupt-remapping-for-x2apic-enabled-system.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From b74aa02d7a30ee5e262072a7d6e8deff10b37924 Mon Sep 17 00:00:00 2001 From: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> Date: Wed, 22 Apr 2020 08:30:02 -0500 Subject: iommu/amd: Fix legacy interrupt remapping for x2APIC-enabled system From: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> commit b74aa02d7a30ee5e262072a7d6e8deff10b37924 upstream. Currently, system fails to boot because the legacy interrupt remapping mode does not enable 128-bit IRTE (GA), which is required for x2APIC support. Fix by using AMD_IOMMU_GUEST_IR_LEGACY_GA mode when booting with kernel option amd_iommu_intr=legacy instead. The initialization logic will check GASup and automatically fallback to using AMD_IOMMU_GUEST_IR_LEGACY if GA mode is not supported. Fixes: 3928aa3f5775 ("iommu/amd: Detect and enable guest vAPIC support") Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> Link: https://lore.kernel.org/r/1587562202-14183-1-git-send-email-suravee.suthikulpanit@xxxxxxx Signed-off-by: Joerg Roedel <jroedel@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/iommu/amd_iommu_init.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/iommu/amd_iommu_init.c +++ b/drivers/iommu/amd_iommu_init.c @@ -2574,7 +2574,7 @@ static int __init parse_amd_iommu_intr(c { for (; *str; ++str) { if (strncmp(str, "legacy", 6) == 0) { - amd_iommu_guest_ir = AMD_IOMMU_GUEST_IR_LEGACY; + amd_iommu_guest_ir = AMD_IOMMU_GUEST_IR_LEGACY_GA; break; } if (strncmp(str, "vapic", 5) == 0) { Patches currently in stable-queue which might be from suravee.suthikulpanit@xxxxxxx are queue-4.9/iommu-amd-fix-legacy-interrupt-remapping-for-x2apic-enabled-system.patch