linux-kernel - [PATCH v10 24/50] KVM: SEV: Add initial SEV-SNP support

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Message-ID: <20231016132819.1002933-25-michael.roth@amd.com>
Date:   Mon, 16 Oct 2023 08:27:53 -0500
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>,
        <linux-kernel@...r.kernel.org>, <tglx@...utronix.de>,
        <mingo@...hat.com>, <jroedel@...e.de>, <thomas.lendacky@....com>,
        <hpa@...or.com>, <ardb@...nel.org>, <pbonzini@...hat.com>,
        <seanjc@...gle.com>, <vkuznets@...hat.com>, <jmattson@...gle.com>,
        <luto@...nel.org>, <dave.hansen@...ux.intel.com>, <slp@...hat.com>,
        <pgonda@...gle.com>, <peterz@...radead.org>,
        <srinivas.pandruvada@...ux.intel.com>, <rientjes@...gle.com>,
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        <vbabka@...e.cz>, <kirill@...temov.name>, <ak@...ux.intel.com>,
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        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        <alpergun@...gle.com>, <jarkko@...nel.org>, <ashish.kalra@....com>,
        <nikunj.dadhania@....com>, <pankaj.gupta@....com>,
        <liam.merwick@...cle.com>, <zhi.a.wang@...el.com>,
        Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH v10 24/50] 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
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 is added incrementally, the later patches adds a new module
parameters that can be used to enabled SEV-SNP in the KVM.

Signed-off-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: Ashish Kalra <ashish.kalra@....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 1cfb9232fc74..4eefc168ebb3 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -59,10 +59,14 @@ 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);
+
+/* enable/disable SEV-SNP support */
+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
@@ -2186,6 +2190,7 @@ 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;
 
@@ -2261,6 +2266,10 @@ 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);
+
+	pr_info("SEV-ES %ssupported: %u ASIDs\n",
+		sev_snp_supported ? "and SEV-SNP " : "", sev_es_asid_count);
 
 out:
 	if (boot_cpu_has(X86_FEATURE_SEV))
@@ -2277,6 +2286,7 @@ void __init sev_hardware_setup(void)
 	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 b7b8bf73cbb9..635430fa641b 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 */
@@ -339,6 +340,13 @@ 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