linux-kernel - [PATCH RFC v8 32/56] KVM: SVM: Add initial SEV-SNP support

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Message-ID: <20230220183847.59159-33-michael.roth@amd.com>
Date:   Mon, 20 Feb 2023 12:38:23 -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>,
        <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>,
        <dovmurik@...ux.ibm.com>, <tobin@....com>, <bp@...en8.de>,
        <vbabka@...e.cz>, <kirill@...temov.name>, <ak@...ux.intel.com>,
        <tony.luck@...el.com>, <marcorr@...gle.com>,
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        <alpergun@...gle.com>, <dgilbert@...hat.com>, <jarkko@...nel.org>,
        <ashish.kalra@....com>, <nikunj.dadhania@....com>,
        Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH RFC v8 32/56] KVM: SVM: 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>
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, 17 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 9e9efb42a766..51db01b282eb 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -58,6 +58,9 @@ module_param_named(sev_es, sev_es_enabled, bool, 0444);
 #define sev_es_enabled false
 #endif /* CONFIG_KVM_AMD_SEV */
 
+/* enable/disable SEV-SNP support */
+static bool sev_snp_enabled;
+
 #define AP_RESET_HOLD_NONE		0
 #define AP_RESET_HOLD_NAE_EVENT		1
 #define AP_RESET_HOLD_MSR_PROTO		2
@@ -2306,6 +2309,7 @@ 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;
 
@@ -2385,12 +2389,16 @@ void __init sev_hardware_setup(void)
 	if (misc_cg_set_capacity(MISC_CG_RES_SEV_ES, sev_es_asid_count))
 		goto out;
 
-	pr_info("SEV-ES supported: %u ASIDs\n", 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:
 	sev_enabled = sev_supported;
 	sev_es_enabled = sev_es_supported;
+	sev_snp_enabled = sev_snp_supported;
 #endif
 }
 
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 5efcf036ccad..8eb1b51e92f5 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -76,6 +76,7 @@ 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 */
@@ -323,6 +324,13 @@ static __always_inline bool sev_es_guest(struct kvm *kvm)
 #endif
 }
 
+static 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