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authorAshish Kalra <ashish.kalra@amd.com>2024-01-25 22:11:03 -0600
committerBorislav Petkov (AMD) <bp@alien8.de>2024-01-29 17:19:28 +0100
commit04d65a9dbb33e20500005e151d720acead78c539 (patch)
treef31e359e49f8c965742e7e585e9977a684fe398e /drivers/iommu
parentacaa4b5c4c854b5009f4d4a5395b2609ad0f4937 (diff)
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iommu/amd: Don't rely on external callers to enable IOMMU SNP support
Currently, the expectation is that the kernel will call amd_iommu_snp_enable() to perform various checks and set the amd_iommu_snp_en flag that the IOMMU uses to adjust its setup routines to account for additional requirements on hosts where SNP is enabled. This is somewhat fragile as it relies on this call being done prior to IOMMU setup. It is more robust to just do this automatically as part of IOMMU initialization, so rework the code accordingly. There is still a need to export information about whether or not the IOMMU is configured in a manner compatible with SNP, so relocate the existing amd_iommu_snp_en flag so it can be used to convey that information in place of the return code that was previously provided by calls to amd_iommu_snp_enable(). While here, also adjust the kernel messages related to IOMMU SNP enablement for consistency/grammar/clarity. Suggested-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> Co-developed-by: Michael Roth <michael.roth@amd.com> Signed-off-by: Michael Roth <michael.roth@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Acked-by: Joerg Roedel <jroedel@suse.de> Link: https://lore.kernel.org/r/20240126041126.1927228-4-michael.roth@amd.com
Diffstat (limited to 'drivers/iommu')
-rw-r--r--drivers/iommu/amd/amd_iommu.h1
-rw-r--r--drivers/iommu/amd/init.c69
2 files changed, 31 insertions, 39 deletions
diff --git a/drivers/iommu/amd/amd_iommu.h b/drivers/iommu/amd/amd_iommu.h
index 8b3601f285fd..c970eae2313d 100644
--- a/drivers/iommu/amd/amd_iommu.h
+++ b/drivers/iommu/amd/amd_iommu.h
@@ -164,5 +164,4 @@ void amd_iommu_domain_set_pgtable(struct protection_domain *domain,
u64 *root, int mode);
struct dev_table_entry *get_dev_table(struct amd_iommu *iommu);
-extern bool amd_iommu_snp_en;
#endif
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index c83bd0c2a1c9..3a4eeb26d515 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3221,6 +3221,36 @@ out:
return true;
}
+static void iommu_snp_enable(void)
+{
+#ifdef CONFIG_KVM_AMD_SEV
+ if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+ return;
+ /*
+ * The SNP support requires that IOMMU must be enabled, and is
+ * not configured in the passthrough mode.
+ */
+ if (no_iommu || iommu_default_passthrough()) {
+ pr_err("SNP: IOMMU disabled or configured in passthrough mode, SNP cannot be supported.\n");
+ return;
+ }
+
+ 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");
+ return;
+ }
+
+ pr_info("IOMMU SNP support enabled.\n");
+
+ /* 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;
+ }
+#endif
+}
+
/****************************************************************************
*
* AMD IOMMU Initialization State Machine
@@ -3256,6 +3286,7 @@ static int __init state_next(void)
break;
case IOMMU_ENABLED:
register_syscore_ops(&amd_iommu_syscore_ops);
+ iommu_snp_enable();
ret = amd_iommu_init_pci();
init_state = ret ? IOMMU_INIT_ERROR : IOMMU_PCI_INIT;
break;
@@ -3766,41 +3797,3 @@ int amd_iommu_pc_set_reg(struct amd_iommu *iommu, u8 bank, u8 cntr, u8 fxn, u64
return iommu_pc_get_set_reg(iommu, bank, cntr, fxn, value, true);
}
-
-#ifdef CONFIG_AMD_MEM_ENCRYPT
-int amd_iommu_snp_enable(void)
-{
- /*
- * The SNP support requires that IOMMU must be enabled, and is
- * not configured in the passthrough mode.
- */
- if (no_iommu || iommu_default_passthrough()) {
- pr_err("SNP: IOMMU is disabled or configured in passthrough mode, SNP cannot be supported");
- return -EINVAL;
- }
-
- /*
- * Prevent enabling SNP after IOMMU_ENABLED state because this process
- * affect how IOMMU driver sets up data structures and configures
- * IOMMU hardware.
- */
- if (init_state > IOMMU_ENABLED) {
- pr_err("SNP: Too late to enable SNP for IOMMU.\n");
- return -EINVAL;
- }
-
- amd_iommu_snp_en = check_feature(FEATURE_SNP);
- if (!amd_iommu_snp_en)
- return -EINVAL;
-
- pr_info("SNP enabled\n");
-
- /* Enforce IOMMU v1 pagetable when SNP is enabled. */
- if (amd_iommu_pgtable != AMD_IOMMU_V1) {
- pr_warn("Force to using AMD IOMMU v1 page table due to SNP\n");
- amd_iommu_pgtable = AMD_IOMMU_V1;
- }
-
- return 0;
-}
-#endif