[PATCH v3 6/7] KVM: SVM: Add support to initialize SEV/SNP functionality in KVM

Ashish Kalra
2025-01-03T20:02:05Z

From: Ashish Kalra <ashish.kalra@amd.com>

Remove platform initialization of SEV/SNP from PSP driver probe time and
move it to KVM module load time so that KVM can do SEV/SNP platform
initialization explicitly if it actually wants to use SEV/SNP
functionality.

With this patch, KVM will explicitly call into the PSP driver at load time
to initialize SEV/SNP by default but this behavior can be altered with KVM
module parameters to not do SEV/SNP platform initialization at module load
time if required. Additionally SEV/SNP platform shutdown is invoked during
KVM module unload time.

Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
arch/x86/kvm/svm/sev.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 943bd074a5d3..0dc8294582c6 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -444,7 +444,6 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp,
if (ret)
goto e_no_asid;

- init_args.probe = false;
ret = sev_platform_init(&init_args);
if (ret)
goto e_free;
@@ -2953,6 +2952,7 @@ void __init sev_set_cpu_caps(void)
void __init sev_hardware_setup(void)
{
unsigned int eax, ebx, ecx, edx, sev_asid_count, sev_es_asid_count;
+ struct sev_platform_init_args init_args = {0};
bool sev_snp_supported = false;
bool sev_es_supported = false;
bool sev_supported = false;
@@ -3069,6 +3069,16 @@ void __init sev_hardware_setup(void)
sev_supported_vmsa_features = 0;
if (sev_es_debug_swap_enabled)
sev_supported_vmsa_features |= SVM_SEV_FEAT_DEBUG_SWAP;
+
+ if (!sev_enabled)
+ return;
+
+ /*
+ * NOTE: Always do SNP INIT regardless of sev_snp_supported
+ * as SNP INIT has to be done to launch legacy SEV/SEV-ES
+ * VMs in case SNP is enabled system-wide.
+ */
+ sev_platform_init(&init_args);
}

void sev_hardware_unsetup(void)
@@ -3084,6 +3094,9 @@ void sev_hardware_unsetup(void)

misc_cg_set_capacity(MISC_CG_RES_SEV, 0);
misc_cg_set_capacity(MISC_CG_RES_SEV_ES, 0);
+
+ /* Do SEV and SNP Shutdown */
+ sev_platform_shutdown();
}

int sev_cpu_init(struct svm_cpu_data *sd)
--
2.34.1