[PATCH Part2 RFC v3 19/37] KVM: SVM: Add KVM_SNP_INIT command

Brijesh Singh
2021-06-02T14:16:56Z

The KVM_SNP_INIT command is used by the hypervisor to initialize the
SEV-SNP platform context. In a typical workflow, this command should be the
first command issued. When creating SEV-SNP guest, the VMM must use this
command instead of the KVM_SEV_INIT or KVM_SEV_ES_INIT.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
arch/x86/include/asm/svm.h | 2 ++
arch/x86/kvm/svm/sev.c | 18 ++++++++++++++++--
include/uapi/linux/kvm.h | 3 +++
3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index b6f358d6b975..65407b6d35a0 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -212,6 +212,8 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
#define SVM_NESTED_CTL_SEV_ENABLE BIT(1)
#define SVM_NESTED_CTL_SEV_ES_ENABLE BIT(2)

+#define SVM_SEV_FEATURES_SNP_ACTIVE BIT(0)
+
struct vmcb_seg {
u16 selector;
u16 attrib;
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index abca2b9dee83..0cd0078baf75 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -230,8 +230,9 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)

static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
{
+ bool es_active = (argp->id == KVM_SEV_ES_INIT || argp->id == KVM_SEV_SNP_INIT);
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
- bool es_active = argp->id == KVM_SEV_ES_INIT;
+ bool snp_active = argp->id == KVM_SEV_SNP_INIT;
int asid, ret;

if (kvm->created_vcpus)
@@ -242,12 +243,16 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
return ret;

sev->es_active = es_active;
+ sev->snp_active = snp_active;
asid = sev_asid_new(sev);
if (asid < 0)
goto e_no_asid;
sev->asid = asid;

- ret = sev_platform_init(&argp->error);
+ if (snp_active)
+ ret = sev_snp_init(&argp->error);
+ else
+ ret = sev_platform_init(&argp->error);
if (ret)
goto e_free;

@@ -591,6 +596,9 @@ static int sev_es_sync_vmsa(struct vcpu_svm *svm)
save->pkru = svm->vcpu.arch.pkru;
save->xss = svm->vcpu.arch.ia32_xss;

+ if (sev_snp_guest(svm->vcpu.kvm))
+ save->sev_features |= SVM_SEV_FEATURES_SNP_ACTIVE;
+
return 0;
}

@@ -1523,6 +1531,12 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
}

switch (sev_cmd.id) {
+ case KVM_SEV_SNP_INIT:
+ if (!sev_snp_enabled) {
+ r = -ENOTTY;
+ goto out;
+ }
+ fallthrough;
case KVM_SEV_ES_INIT:
if (!sev_es_enabled) {
r = -ENOTTY;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 3fd9a7e9d90c..f3a86d3a8f04 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1678,6 +1678,9 @@ enum sev_cmd_id {
/* Guest Migration Extension */
KVM_SEV_SEND_CANCEL,

+ /* SNP specific commands */
+ KVM_SEV_SNP_INIT = 255,
+
KVM_SEV_NR_MAX,
};

--
2.17.1