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 3bdb380d23e9a93c9ab9399afe7872645964b2bd..16a4567984b81f4a17d005d58ff6e7e09121c58a 100644 (file)
--- 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;
        }