linux-kernel - [PATCH v11 14/35] KVM: SEV: Add initial SEV-SNP support

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Message-ID: <20231230172351.574091-15-michael.roth@amd.com>
Date: Sat, 30 Dec 2023 11:23:30 -0600
From: Michael Roth <michael.roth@....com>
To: <kvm@...r.kernel.org>
CC: <linux-coco@...ts.linux.dev>, <linux-mm@...ck.org>,
	<linux-crypto@...r.kernel.org>, <x86@...nel.org>,
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	<pankaj.gupta@....com>, <liam.merwick@...cle.com>, <zhi.a.wang@...el.com>,
	Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH v11 14/35] KVM: SEV: Add initial SEV-SNP support

From: Brijesh Singh <brijesh.singh@....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 and integrity protection to help prevent malicious
hypervisor-based attacks such as data replay, memory re-mapping, and
more, to create an isolated execution environment.

Implement some initial infrastructure in KVM to check/report when SNP is
enabled on the system.

Signed-off-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: Ashish Kalra <ashish.kalra@....com>
[mdr: commit fixups, use similar ASID reporting as with SEV/SEV-ES]
Signed-off-by: Michael Roth <michael.roth@....com>
---
 arch/x86/kvm/svm/sev.c | 10 ++++++++++
 arch/x86/kvm/svm/svm.h |  8 ++++++++
 2 files changed, 18 insertions(+)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index d6e206d21750..18c09863377b 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -59,10 +59,13 @@ module_param_named(sev_es, sev_es_enabled, bool, 0444);
 /* enable/disable SEV-ES DebugSwap support */
 static bool sev_es_debug_swap_enabled = true;
 module_param_named(debug_swap, sev_es_debug_swap_enabled, bool, 0444);
+
+static bool sev_snp_enabled;
 #else
 #define sev_enabled false
 #define sev_es_enabled false
 #define sev_es_debug_swap_enabled false
+#define sev_snp_enabled false
 #endif /* CONFIG_KVM_AMD_SEV */
 
 #define AP_RESET_HOLD_NONE		0
@@ -2189,6 +2192,7 @@ void __init sev_hardware_setup(void)
 {
 #ifdef CONFIG_KVM_AMD_SEV
 	unsigned int eax, ebx, ecx, edx, sev_asid_count, sev_es_asid_count;
+	bool sev_snp_supported = false;
 	bool sev_es_supported = false;
 	bool sev_supported = false;
 
@@ -2267,6 +2271,7 @@ void __init sev_hardware_setup(void)
 	sev_es_asid_count = min_sev_asid - 1;
 	WARN_ON_ONCE(misc_cg_set_capacity(MISC_CG_RES_SEV_ES, sev_es_asid_count));
 	sev_es_supported = true;
+	sev_snp_supported = sev_snp_enabled && cpu_feature_enabled(X86_FEATURE_SEV_SNP);
 
 out:
 	if (boot_cpu_has(X86_FEATURE_SEV))
@@ -2277,12 +2282,17 @@ void __init sev_hardware_setup(void)
 		pr_info("SEV-ES %s (ASIDs %u - %u)\n",
 			sev_es_supported ? "enabled" : "disabled",
 			min_sev_asid > 1 ? 1 : 0, min_sev_asid - 1);
+	if (boot_cpu_has(X86_FEATURE_SEV_SNP))
+		pr_info("SEV-SNP %s (ASIDs %u - %u)\n",
+			sev_snp_supported ? "enabled" : "disabled",
+			min_sev_asid > 1 ? 1 : 0, min_sev_asid - 1);
 
 	sev_enabled = sev_supported;
 	sev_es_enabled = sev_es_supported;
 	if (!sev_es_enabled || !cpu_feature_enabled(X86_FEATURE_DEBUG_SWAP) ||
 	    !cpu_feature_enabled(X86_FEATURE_NO_NESTED_DATA_BP))
 		sev_es_debug_swap_enabled = false;
+	sev_snp_enabled = sev_snp_supported;
 #endif
 }
 
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index d0f8167ada7c..a3e27c82866b 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -79,6 +79,7 @@ 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 */
@@ -341,6 +342,13 @@ static __always_inline bool sev_es_guest(struct kvm *kvm)
 #endif
 }
 
+static __always_inline bool sev_snp_guest(struct kvm *kvm)
+{
+	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+
+	return sev_es_guest(kvm) && sev->snp_active;
+}
+
 static inline void vmcb_mark_all_dirty(struct vmcb *vmcb)
 {
 	vmcb->control.clean = 0;
-- 
2.25.1