1 files changed, 30 insertions, 4 deletions

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index c5cd92edada0..2fecfed75e54 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3194,7 +3194,7 @@ out:
 	return true;
 }
 
-static void iommu_snp_enable(void)
+static __init void iommu_snp_enable(void)
 {
 #ifdef CONFIG_KVM_AMD_SEV
 	if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
@@ -3219,6 +3219,14 @@ static void iommu_snp_enable(void)
 		goto disable_snp;
 	}
 
+	/*
+	 * Enable host SNP support once SNP support is checked on IOMMU.
+	 */
+	if (snp_rmptable_init()) {
+		pr_warn("SNP: RMP initialization failed, SNP cannot be supported.\n");
+		goto disable_snp;
+	}
+
 	pr_info("IOMMU SNP support enabled.\n");
 	return;
 
@@ -3318,6 +3326,19 @@ static int __init iommu_go_to_state(enum iommu_init_state state)
 		ret = state_next();
 	}
 
+	/*
+	 * SNP platform initilazation requires IOMMUs to be fully configured.
+	 * If the SNP support on IOMMUs has NOT been checked, simply mark SNP
+	 * as unsupported. If the SNP support on IOMMUs has been checked and
+	 * host SNP support enabled but RMP enforcement has not been enabled
+	 * in IOMMUs, then the system is in a half-baked state, but can limp
+	 * along as all memory should be Hypervisor-Owned in the RMP. WARN,
+	 * but leave SNP as "supported" to avoid confusing the kernel.
+	 */
+	if (ret && cc_platform_has(CC_ATTR_HOST_SEV_SNP) &&
+	    !WARN_ON_ONCE(amd_iommu_snp_en))
+		cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
+
 	return ret;
 }
 
@@ -3426,18 +3447,23 @@ void __init amd_iommu_detect(void)
 	int ret;
 
 	if (no_iommu || (iommu_detected && !gart_iommu_aperture))
-		return;
+		goto disable_snp;
 
 	if (!amd_iommu_sme_check())
-		return;
+		goto disable_snp;
 
 	ret = iommu_go_to_state(IOMMU_IVRS_DETECTED);
 	if (ret)
-		return;
+		goto disable_snp;
 
 	amd_iommu_detected = true;
 	iommu_detected = 1;
 	x86_init.iommu.iommu_init = amd_iommu_init;
+	return;
+
+disable_snp:
+	if (cc_platform_has(CC_ATTR_HOST_SEV_SNP))
+		cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
 }
 
 /****************************************************************************