When the IOMMU SNP support bit is set in the IOMMU Extended Features
register, hardware re-purposes the following registers:
1. IOMMU Exclusion Base register (MMIO offset 0020h) to
Completion Wait Write-Back (CWWB) Base register
2. IOMMU Exclusion Range Limit (MMIO offset 0028h) to
Completion Wait Write-Back (CWWB) Range Limit register
and requires the IOMMU CWWB semaphore base and range to be programmed
in the register offset 0020h and 0028h accordingly.
Cc: Brijesh Singh <brijesh.si...@amd.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com>
---
drivers/iommu/amd/amd_iommu_types.h | 1 +
drivers/iommu/amd/init.c | 26 ++++++++++++++++++++++++++
2 files changed, 27 insertions(+)
diff --git a/drivers/iommu/amd/amd_iommu_types.h
b/drivers/iommu/amd/amd_iommu_types.h
index 1e7966c73707..f696ac7c5f89 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -93,6 +93,7 @@
#define FEATURE_PC (1ULL<<9)
#define FEATURE_GAM_VAPIC (1ULL<<21)
#define FEATURE_EPHSUP (1ULL<<50)
+#define FEATURE_SNP (1ULL<<63)
#define FEATURE_PASID_SHIFT 32
#define FEATURE_PASID_MASK (0x1fULL << FEATURE_PASID_SHIFT)
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index febc072f2717..c55df4347487 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -359,6 +359,29 @@ static void iommu_set_exclusion_range(struct amd_iommu
*iommu)
&entry, sizeof(entry));
}
+static void iommu_set_cwwb_range(struct amd_iommu *iommu)
+{
+ u64 start = iommu_virt_to_phys((void *)iommu->cmd_sem);
+ u64 entry = start & PM_ADDR_MASK;
+
+ if (!iommu_feature(iommu, FEATURE_SNP))
+ return;
+
+ /* Note:
+ * Re-purpose Exclusion base/limit registers for Completion wait
+ * write-back base/limit.
+ */
+ memcpy_toio(iommu->mmio_base + MMIO_EXCL_BASE_OFFSET,
+ &entry, sizeof(entry));
+
+ /* Note:
+ * Default to 4 Kbytes, which can be specified by setting base
+ * address equal to the limit address.
+ */
+ memcpy_toio(iommu->mmio_base + MMIO_EXCL_LIMIT_OFFSET,
+ &entry, sizeof(entry));
+}
+
/* Programs the physical address of the device table into the IOMMU hardware */
static void iommu_set_device_table(struct amd_iommu *iommu)
{
@@ -1901,6 +1924,9 @@ static int __init amd_iommu_init_pci(void)
ret = iommu_init_pci(iommu);
if (ret)
break;
+
+ /* Need to setup range after PCI init */
+ iommu_set_cwwb_range(iommu);
}
/*
--
2.17.1
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