From: Sean Christopherson <seanjc@google.com>
Date: Sat, 15 Mar 2025 03:09:28 +0000 (-0700)
Subject: iommu/amd: Explicitly bail from enable_iommus_vapic() when in legacy mode
X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=b30e046cfdcc883c627a1d0ede7e2d10d5c1a22c;p=thirdparty%2Fkernel%2Flinux.git

iommu/amd: Explicitly bail from enable_iommus_vapic() when in legacy mode

Bail early from enable_iommus_vapic() if IOMMUs are configured for either
of the legacy modes, as it's absurdly difficult to see that
iommu_ga_log_enable() is guaranteed to fail because iommu_init_ga_log()
skips allocating the ga_log.

Opportunistically have iommu_ga_log_enable() WARN if it's called without
IOMMUs being configured to support AVIC/vAPIC.

Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 3bdb380d23e9a..16a4567984b81 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -972,8 +972,8 @@ static int iommu_init_ga_log(struct amd_iommu *iommu)
 {
 	int nid = iommu->dev ? dev_to_node(&iommu->dev->dev) : NUMA_NO_NODE;
 
-	if (!AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir))
-		return 0;
+	if (WARN_ON_ONCE(!AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir)))
+		return -EINVAL;
 
 	iommu->ga_log = iommu_alloc_pages_node_sz(nid, GFP_KERNEL, GA_LOG_SIZE);
 	if (!iommu->ga_log)
@@ -3022,8 +3022,10 @@ static void enable_iommus_vapic(void)
 			return;
 	}
 
-	if (AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir) &&
-	    !check_feature(FEATURE_GAM_VAPIC)) {
+	if (!AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir))
+		return;
+
+	if (!check_feature(FEATURE_GAM_VAPIC)) {
 		amd_iommu_guest_ir = AMD_IOMMU_GUEST_IR_LEGACY_GA;
 		return;
 	}