Re: [PATCH Part2 v5 02/45] iommu/amd: Introduce function to check SEV-SNP support

SEV-SNP feature.

Signed-off-by: Brijesh Singh <redacted>
---
 drivers/iommu/amd/init.c | 30 ++++++++++++++++++++++++++++++
 include/linux/iommu.h    |  9 +++++++++
 2 files changed, 39 insertions(+)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 46280e6e1535..bd420fb71126 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c

@@ -3320,3 +3320,33 @@ 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);
 }
+
+bool iommu_sev_snp_supported(void)
+{
+	struct amd_iommu *iommu;
+
+	/*
+	 * The SEV-SNP support requires that IOMMU must be enabled, and is
+	 * not configured in the passthrough mode.
+	 */
+	if (no_iommu || iommu_default_passthrough()) {
+		pr_err("SEV-SNP: IOMMU is either disabled or configured in passthrough mode.\n");
+		return false;
+	}
+
+	/*
+	 * Iterate through all the IOMMUs and verify the SNPSup feature is
+	 * enabled.
+	 */
+	for_each_iommu(iommu) {
+		if (!iommu_feature(iommu, FEATURE_SNP)) {
+			pr_err("SNPSup is disabled (devid: %02x:%02x.%x)\n",
+			       PCI_BUS_NUM(iommu->devid), PCI_SLOT(iommu->devid),
+			       PCI_FUNC(iommu->devid));
+			return false;
+		}
+	}
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(iommu_sev_snp_supported);

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 32d448050bf7..269abc17b2c3 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h

@@ -604,6 +604,12 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev,
 void iommu_sva_unbind_device(struct iommu_sva *handle);
 u32 iommu_sva_get_pasid(struct iommu_sva *handle);
 
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+bool iommu_sev_snp_supported(void);
+#else
+static inline bool iommu_sev_snp_supported(void) { return false; }
+#endif
+
 #else /* CONFIG_IOMMU_API */
 
 struct iommu_ops {};

@@ -999,6 +1005,9 @@ static inline struct iommu_fwspec *dev_iommu_fwspec_get(struct device *dev)
 {
 	return NULL;
 }
+
+static inline bool iommu_sev_snp_supported(void) { return false; }
+