diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 5d9685f92e5c36bb82472637c66150f6b6fce215..1581246491b544b106cd65b8955a12a11cc1de8b 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -531,6 +531,7 @@ static inline void __init snp_secure_tsc_init(void) { }
 
 #ifdef CONFIG_KVM_AMD_SEV
 bool snp_probe_rmptable_info(void);
+int snp_rmptable_init(void);
 int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level);
 void snp_dump_hva_rmpentry(unsigned long address);
 int psmash(u64 pfn);
@@ -541,6 +542,7 @@ void kdump_sev_callback(void);
 void snp_fixup_e820_tables(void);
 #else
 static inline bool snp_probe_rmptable_info(void) { return false; }
+static inline int snp_rmptable_init(void) { return -ENOSYS; }
 static inline int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) { return -ENODEV; }
 static inline void snp_dump_hva_rmpentry(unsigned long address) {}
 static inline int psmash(u64 pfn) { return -ENODEV; }
diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index 1dcc027ec77e7517b84b1a89c079406db05ba55e..42e74a5a7d786d4df3a8c8aaa460c9055fc8fbef 100644
--- a/arch/x86/virt/svm/sev.c
+++ b/arch/x86/virt/svm/sev.c
@@ -505,19 +505,19 @@ static bool __init setup_rmptable(void)
  * described in the SNP_INIT_EX firmware command description in the SNP
  * firmware ABI spec.
  */
-static int __init snp_rmptable_init(void)
+int __init snp_rmptable_init(void)
 {
 	unsigned int i;
 	u64 val;
 
-	if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
-		return 0;
+	if (WARN_ON_ONCE(!cc_platform_has(CC_ATTR_HOST_SEV_SNP)))
+		return -ENOSYS;
 
-	if (!amd_iommu_snp_en)
-		goto nosnp;
+	if (WARN_ON_ONCE(!amd_iommu_snp_en))
+		return -ENOSYS;
 
 	if (!setup_rmptable())
-		goto nosnp;
+		return -ENOSYS;
 
 	/*
 	 * Check if SEV-SNP is already enabled, this can happen in case of
@@ -530,7 +530,7 @@ static int __init snp_rmptable_init(void)
 	/* Zero out the RMP bookkeeping area */
 	if (!clear_rmptable_bookkeeping()) {
 		free_rmp_segment_table();
-		goto nosnp;
+		return -ENOSYS;
 	}
 
 	/* Zero out the RMP entries */
@@ -562,17 +562,8 @@ static int __init snp_rmptable_init(void)
 	crash_kexec_post_notifiers = true;
 
 	return 0;
-
-nosnp:
-	cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
-	return -ENOSYS;
 }
 
-/*
- * This must be called after the IOMMU has been initialized.
- */
-device_initcall(snp_rmptable_init);
-
 static void set_rmp_segment_info(unsigned int segment_shift)
 {
 	rmp_segment_shift = segment_shift;
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index c5cd92edada06156c665847b47f03c78990bfe06..2fecfed75e5437a86dd546670a89dd3f4644365d 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3194,7 +3194,7 @@ static bool __init detect_ivrs(void)
 	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);
 }
 
 /****************************************************************************