The AMD BIOS'es "SEV-TIO" switch is reported to the OS via IOMMU
Extended Feature 2 register (EFR2), bit 1.
Add helper to parse the bit and report the feature presense.
Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxx>
---
drivers/iommu/amd/amd_iommu_types.h | 1 +
include/linux/amd-iommu.h | 2 ++
drivers/iommu/amd/init.c | 9 +++++++++
3 files changed, 12 insertions(+)
diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index 0bbda60d3cdc..b086fb632990 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -108,6 +108,7 @@
/* Extended Feature 2 Bits */
+#define FEATURE_SEVSNPIO_SUP BIT_ULL(1)
#define FEATURE_SNPAVICSUP GENMASK_ULL(7, 5)
#define FEATURE_SNPAVICSUP_GAM(x) \
(FIELD_GET(FEATURE_SNPAVICSUP, x) == 0x1)
diff --git a/include/linux/amd-iommu.h b/include/linux/amd-iommu.h
index 062fbd4c9b77..cb1b94fdb63c 100644
--- a/include/linux/amd-iommu.h
+++ b/include/linux/amd-iommu.h
@@ -32,10 +32,12 @@ struct task_struct;
struct pci_dev;
extern void amd_iommu_detect(void);
+extern bool amd_iommu_sev_tio_supported(void);
#else /* CONFIG_AMD_IOMMU */
static inline void amd_iommu_detect(void) { }
+static inline bool amd_iommu_sev_tio_supported(void) { return false; }
#endif /* CONFIG_AMD_IOMMU */
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index c5cd92edada0..9f2756d3bd73 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -2156,6 +2156,9 @@ static void print_iommu_info(void)
if (check_feature(FEATURE_SNP))
pr_cont(" SNP");
+ if (check_feature2(FEATURE_SEVSNPIO_SUP))
+ pr_cont(" SEV-TIO");
+
pr_cont("\n");
}
@@ -3856,4 +3859,10 @@ int amd_iommu_snp_disable(void)
return 0;
}
EXPORT_SYMBOL_GPL(amd_iommu_snp_disable);
+
+bool amd_iommu_sev_tio_supported(void)
+{
+ return check_feature2(FEATURE_SEVSNPIO_SUP);
+}
+EXPORT_SYMBOL_GPL(amd_iommu_sev_tio_supported);
#endif
--
2.47.1
