iommu/amd: Do not support IOMMUv2 APIs when SNP is enabled

ssuthiku-amd · joergroedel · commit 30315e71b426 · 2022-07-15T10:44:03.000+02:00
The IOMMUv2 APIs (for supporting shared virtual memory with PASID) configures the domain with IOMMU v2 page table, and sets DTE[Mode]=0. This configuration cannot be supported on SNP-enabled system. Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Link: https://lore.kernel.org/r/20220713225651.20758-10-suravee.suthikulpanit@amd.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
@@ -3458,7 +3458,12 @@ __setup("ivrs_acpihid",		parse_ivrs_acpihid);
 
 bool amd_iommu_v2_supported(void)
 {
-	return amd_iommu_v2_present;
+	/*
+	 * Since DTE[Mode]=0 is prohibited on SNP-enabled system
+	 * (i.e. EFR[SNPSup]=1), IOMMUv2 page table cannot be used without
+	 * setting up IOMMUv1 page table.
+	 */
+	return amd_iommu_v2_present && !amd_iommu_snp_en;
 }
 EXPORT_SYMBOL(amd_iommu_v2_supported);
 

Original file line number	Diff line number	Diff line change
`@@ -3458,7 +3458,12 @@ __setup("ivrs_acpihid", parse_ivrs_acpihid);`
`3458`	`3458`
`3459`	`3459`	`bool amd_iommu_v2_supported(void)`
`3460`	`3460`	`{`
`3461`		`- return amd_iommu_v2_present;`
	`3461`	`+ /*`
	`3462`	`+ * Since DTE[Mode]=0 is prohibited on SNP-enabled system`
	`3463`	`+ * (i.e. EFR[SNPSup]=1), IOMMUv2 page table cannot be used without`
	`3464`	`+ * setting up IOMMUv1 page table.`
	`3465`	`+ */`
	`3466`	`+ return amd_iommu_v2_present && !amd_iommu_snp_en;`
`3462`	`3467`	`}`
`3463`	`3468`	`EXPORT_SYMBOL(amd_iommu_v2_supported);`
`3464`	`3469`