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authorVasant Hegde <vasant.hegde@amd.com>2024-04-10 08:57:02 +0000
committerJoerg Roedel <jroedel@suse.de>2024-04-12 12:03:22 +0200
commitb650b38b006053ef96e90b8e3f7e6edc7845cd57 (patch)
tree6bccfddd6b63773af33b517543490bd9a64dc390 /drivers/iommu
parent84b1cec4fac5889b6d138d4b5ff6f2d5ef126c5e (diff)
iommu/amd: Do not enable SNP when V2 page table is enabled
DTE[Mode]=0 is not supported when SNP is enabled in the host. That means to support SNP, IOMMU must be configured with V1 page table (See IOMMU spec [1] for the details). If user passes kernel command line to configure IOMMU domains with v2 page table (amd_iommu=pgtbl_v2) then disable SNP as the user asked by not forcing the page table to v1. [1] https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/specifications/48882_IOMMU.pdf Cc: Ashish Kalra <ashish.kalra@amd.com> Cc: Michael Roth <michael.roth@amd.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Vasant Hegde <vasant.hegde@amd.com> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20240410085702.31869-1-vasant.hegde@amd.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu')
-rw-r--r--drivers/iommu/amd/init.c21
1 files changed, 11 insertions, 10 deletions
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 33228c1c8980..a714eb08c08b 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3232,28 +3232,29 @@ static void iommu_snp_enable(void)
return;
/*
* The SNP support requires that IOMMU must be enabled, and is
- * not configured in the passthrough mode.
+ * configured with V1 page table (DTE[Mode] = 0 is not supported).
*/
if (no_iommu || iommu_default_passthrough()) {
pr_err("SNP: IOMMU disabled or configured in passthrough mode, SNP cannot be supported.\n");
- cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
- return;
+ goto disable_snp;
+ }
+
+ if (amd_iommu_pgtable != AMD_IOMMU_V1) {
+ pr_warn("SNP: IOMMU is configured with V2 page table mode, SNP cannot be supported.\n");
+ goto disable_snp;
}
amd_iommu_snp_en = check_feature(FEATURE_SNP);
if (!amd_iommu_snp_en) {
pr_err("SNP: IOMMU SNP feature not enabled, SNP cannot be supported.\n");
- cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
- return;
+ goto disable_snp;
}
pr_info("IOMMU SNP support enabled.\n");
+ return;
- /* Enforce IOMMU v1 pagetable when SNP is enabled. */
- if (amd_iommu_pgtable != AMD_IOMMU_V1) {
- pr_warn("Forcing use of AMD IOMMU v1 page table due to SNP.\n");
- amd_iommu_pgtable = AMD_IOMMU_V1;
- }
+disable_snp:
+ cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
#endif
}