[RFC PATCH v2 5/7] iommu/amd: Don't fail snp_enable when running virtualized

[Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>]

Hyper-V VMs do not have access to an IOMMU but can support hosting SNP
VMs. amd_iommu_snp_enable() is on the SNP init path and should not fail
in that case.

Signed-off-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
---
 drivers/iommu/amd/init.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index d1270e3c5baf..8049dbe78a27 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3619,6 +3619,12 @@ int amd_iommu_pc_set_reg(struct amd_iommu *iommu, u8 bank, u8 cntr, u8 fxn, u64
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 int amd_iommu_snp_enable(void)
 {
+	/*
+	 * If we're running virtualized there doesn't have to be an IOMMU for SNP to work.
+	 */
+	if (init_state == IOMMU_NOT_FOUND && boot_cpu_has(X86_FEATURE_HYPERVISOR))
+		return 0;
+
 	/*
 	 * The SNP support requires that IOMMU must be enabled, and is
 	 * not configured in the passthrough mode.
-- 
2.25.1