[PATCH AUTOSEL 5.4 34/35] iommu/amd: Fix legacy interrupt remapping for x2APIC-enabled system

[Sasha Levin]

From: Suravee Suthikulpanit <suravee.suthikulpanit at amd.com>

[ Upstream commit b74aa02d7a30ee5e262072a7d6e8deff10b37924 ]

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 at amd.com>
Link: https://lore.kernel.org/r/1587562202-14183-1-git-send-email-suravee.suthikulpanit@amd.com
Signed-off-by: Joerg Roedel <jroedel at suse.de>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/iommu/amd_iommu_init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index b5ae9f7c0510b..ef14b00fa94b4 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -2946,7 +2946,7 @@ static int __init parse_amd_iommu_intr(char *str)
 {
 	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) {
-- 
2.20.1