[RFC Part2 PATCH 13/30] KVM: SVM: add initial SEV-SNP support

[Brijesh Singh <brijesh.singh@amd.com>]

The next generation of SEV is called SEV-SNP (Secure Nested Paging).
SEV-SNP builds upon existing SEV and SEV-ES functionality  while adding new
hardware based security protection. SEV-SNP adds strong memory encryption
integrity protection to help prevent malicious hypervisor-based attacks
such as data replay, memory re-mapping, and more, to create an isolated
execution environment.

The SNP feature can be enabled in the KVM by passing the sev-snp module
parameter.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 arch/x86/kvm/svm/sev.c | 17 +++++++++++++++++
 arch/x86/kvm/svm/svm.c |  5 +++++
 arch/x86/kvm/svm/svm.h | 13 +++++++++++++
 3 files changed, 35 insertions(+)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 48017fef1cd9..b720837faf5a 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -19,6 +19,7 @@
 #include <asm/fpu/internal.h>
 
 #include <asm/trapnr.h>
+#include <asm/sev-snp.h>
 
 #include "x86.h"
 #include "svm.h"
@@ -1249,6 +1250,7 @@ void sev_vm_destroy(struct kvm *kvm)
 void __init sev_hardware_setup(void)
 {
 	unsigned int eax, ebx, ecx, edx;
+	bool sev_snp_supported = false;
 	bool sev_es_supported = false;
 	bool sev_supported = false;
 
@@ -1298,9 +1300,24 @@ void __init sev_hardware_setup(void)
 	pr_info("SEV-ES supported: %u ASIDs\n", min_sev_asid - 1);
 	sev_es_supported = true;
 
+	/* SEV-SNP support requested? */
+	if (!sev_snp)
+		goto out;
+
+	/* Does the CPU support SEV-SNP? */
+	if (!boot_cpu_has(X86_FEATURE_SEV_SNP))
+		goto out;
+
+	if (!snp_key_active())
+		goto out;
+
+	pr_info("SEV-SNP supported: %u ASIDs\n", min_sev_asid - 1);
+	sev_snp_supported = true;
+
 out:
 	sev = sev_supported;
 	sev_es = sev_es_supported;
+	sev_snp = sev_snp_supported;
 }
 
 void sev_hardware_teardown(void)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 3442d44ca53b..aa7ff4685c87 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -197,6 +197,10 @@ module_param(sev, int, 0444);
 int sev_es = IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT);
 module_param(sev_es, int, 0444);
 
+/* enable/disable SEV-SNP support */
+int sev_snp = IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT);
+module_param(sev_snp, int, 0444);
+
 bool __read_mostly dump_invalid_vmcb;
 module_param(dump_invalid_vmcb, bool, 0644);
 
@@ -986,6 +990,7 @@ static __init int svm_hardware_setup(void)
 	} else {
 		sev = false;
 		sev_es = false;
+		sev_snp = false;
 	}
 
 	svm_adjust_mmio_mask();
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 6e7d070f8b86..3dd60d2a567a 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -73,6 +73,7 @@ enum {
 struct kvm_sev_info {
 	bool active;		/* SEV enabled guest */
 	bool es_active;		/* SEV-ES enabled guest */
+	bool snp_active;	/* SEV-SNP enabled guest */
 	unsigned int asid;	/* ASID used for this guest */
 	unsigned int handle;	/* SEV firmware handle */
 	int fd;			/* SEV device fd */
@@ -241,6 +242,17 @@ static inline bool sev_es_guest(struct kvm *kvm)
 #endif
 }
 
+static inline bool sev_snp_guest(struct kvm *kvm)
+{
+#ifdef CONFIG_KVM_AMD_SEV
+	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+
+	return sev_es_guest(kvm) && sev->snp_active;
+#else
+	return false;
+#endif
+}
+
 static inline void vmcb_mark_all_dirty(struct vmcb *vmcb)
 {
 	vmcb->control.clean = 0;
@@ -407,6 +419,7 @@ static inline bool gif_set(struct vcpu_svm *svm)
 
 extern int sev;
 extern int sev_es;
+extern int sev_snp;
 extern bool dump_invalid_vmcb;
 
 u32 svm_msrpm_offset(u32 msr);
-- 
2.17.1