[PATCH v5 6/7] KVM: SVM: Add support to initialize SEV/SNP functionality in KVM

Ashish Kalra
2025-02-25T21:01:47Z

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

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

Add support for KVM to explicitly call into the CCP driver at load time
to initialize SEV/SNP. If required, this behavior can be altered with KVM
module parameters to not do SEV/SNP platform initialization at module load
time. Additionally, a corresponding SEV/SNP platform shutdown is invoked
during KVM module unload time.

Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
arch/x86/kvm/svm/sev.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 74525651770a..0bc6c0486071 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2933,6 +2933,7 @@ 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;
@@ -3059,6 +3060,17 @@ 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;
+
+ /*
+ * Always perform SEV initialization at setup time to avoid
+ * complications when performing SEV initialization later
+ * (such as suspending active guests, etc.).
+ */
+ init_args.probe = true;
+ sev_platform_init(&init_args);
}

void sev_hardware_unsetup(void)
@@ -3074,6 +3086,9 @@ 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