From: Sean Christopherson <seanjc@xxxxxxxxxx>
This patch fixes the current SNP host enabling code and effectively SNP
which is broken with respect to the KVM module being built-in.
SNP check on IOMMU is done during IOMMU PCI init (IOMMU_PCI_INIT stage).
And for that reason snp_rmptable_init() is currently invoked via
device_initcall() and cannot be invoked via subsys_initcall() as core
IOMMU subsystem gets initialized via subsys_initcall().
Essentially SNP host enabling code should be invoked before KVM
initialization, which is currently not the case when KVM is built-in
as SNP host support is enabled via device_initcall() which is
required as SNP check on IOMMU is done during IOMMU PCI init.
Hence, call snp_rmptable_init() early and directly from
iommu_snp_enable() (after checking and enabling IOMMU SNP support)
which enables SNP host support before KVM initialization with
kvm_amd module built-in.
Add additional handling for `iommu=off` or `amd_iommu=off` options.
If IOMMU initialization fails and iommu_snp_enable() is never reached,
CC_ATTR_HOST_SEV_SNP will be left set but that will cause PSP driver's
SNP_INIT to fail as IOMMU SNP sanity checks in SNP firmware will fail
as below:
[ 9.723114] ccp 0000:23:00.1: sev enabled
[ 9.727602] ccp 0000:23:00.1: psp enabled
[ 9.732527] ccp 0000:a2:00.1: enabling device (0000 -> 0002)
[ 9.739098] ccp 0000:a2:00.1: no command queues available
[ 9.745167] ccp 0000:a2:00.1: psp enabled
[ 9.805337] ccp 0000:23:00.1: SEV-SNP: failed to INIT rc -5, error 0x3
[ 9.866426] ccp 0000:23:00.1: SEV API:1.53 build:5
...
and that will cause CC_ATTR_HOST_SEV_SNP flag to be cleared.
Fixes: 04d65a9dbb33 ("iommu/amd: Don't rely on external callers to enable IOMMU SNP support")
Co-developed-by: Vasant Hegde <vasant.hegde@xxxxxxx>
Signed-off-by: Vasant Hegde <vasant.hegde@xxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
---
drivers/iommu/amd/init.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index c5cd92edada0..ee887aa4442f 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3194,7 +3194,7 @@ static bool __init detect_ivrs(void)
return true;
}
-static void iommu_snp_enable(void)
+static __init void iommu_snp_enable(void)
{
#ifdef CONFIG_KVM_AMD_SEV
if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
@@ -3219,6 +3219,11 @@ static void iommu_snp_enable(void)
goto disable_snp;
}
+ if (snp_rmptable_init()) {
+ pr_warn("SNP: RMP initialization failed, SNP cannot be supported.\n");
+ goto disable_snp;
+ }
+
pr_info("IOMMU SNP support enabled.\n");
return;
@@ -3426,18 +3431,23 @@ void __init amd_iommu_detect(void)
int ret;
if (no_iommu || (iommu_detected && !gart_iommu_aperture))
- return;
+ goto disable_snp;
if (!amd_iommu_sme_check())
- return;
+ goto disable_snp;
ret = iommu_go_to_state(IOMMU_IVRS_DETECTED);
if (ret)
- return;
+ goto disable_snp;
amd_iommu_detected = true;
iommu_detected = 1;
x86_init.iommu.iommu_init = amd_iommu_init;
+ return;
+
+disable_snp:
+ if (cc_platform_has(CC_ATTR_HOST_SEV_SNP))
+ cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
}
/****************************************************************************
--
2.34.1
