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From: Brijesh Singh <brijesh.singh@amd.com>
To: x86@kernel.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, linux-efi@vger.kernel.org,
	platform-driver-x86@vger.kernel.org, linux-coco@lists.linux.dev,
	linux-mm@kvack.org, linux-crypto@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Joerg Roedel <jroedel@suse.de>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>,
	Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Sergio Lopez <slp@redhat.com>, Peter Gonda <pgonda@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
	David Rientjes <rientjes@google.com>,
	Dov Murik <dovmurik@linux.ibm.com>,
	Tobin Feldman-Fitzthum <tobin@ibm.com>,
	Borislav Petkov <bp@alien8.de>,
	Michael Roth <michael.roth@amd.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	tony.luck@intel.com, npmccallum@redhat.com,
	brijesh.ksingh@gmail.com, Brijesh Singh <brijesh.singh@amd.com>
Subject: [PATCH Part1 RFC v4 06/36] x86/sev: check SEV-SNP features support
Date: Wed,  7 Jul 2021 13:14:36 -0500	[thread overview]
Message-ID: <20210707181506.30489-7-brijesh.singh@amd.com> (raw)
In-Reply-To: <20210707181506.30489-1-brijesh.singh@amd.com>

Version 2 of the GHCB specification added the advertisement of features
that are supported by the hypervisor. If hypervisor supports the SEV-SNP
then it must set the SEV-SNP features bit to indicate that the base
SEV-SNP is supported.

Check the SEV-SNP feature while establishing the GHCB, if failed,
terminate the guest.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 arch/x86/boot/compressed/sev.c    | 26 ++++++++++++++++++++++++--
 arch/x86/include/asm/sev-common.h |  3 +++
 arch/x86/kernel/sev.c             |  8 ++++++--
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
index 7760959fe96d..7be325d9b09f 100644
--- a/arch/x86/boot/compressed/sev.c
+++ b/arch/x86/boot/compressed/sev.c
@@ -25,6 +25,7 @@
 
 struct ghcb boot_ghcb_page __aligned(PAGE_SIZE);
 struct ghcb *boot_ghcb;
+static u64 msr_sev_status;
 
 /*
  * Copy a version of this function here - insn-eval.c can't be used in
@@ -119,11 +120,32 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt,
 /* Include code for early handlers */
 #include "../../kernel/sev-shared.c"
 
-static bool early_setup_sev_es(void)
+static inline bool sev_snp_enabled(void)
+{
+	unsigned long low, high;
+
+	if (!msr_sev_status) {
+		asm volatile("rdmsr\n"
+			     : "=a" (low), "=d" (high)
+			     : "c" (MSR_AMD64_SEV));
+		msr_sev_status = (high << 32) | low;
+	}
+
+	return msr_sev_status & MSR_AMD64_SEV_SNP_ENABLED;
+}
+
+static bool do_early_sev_setup(void)
 {
 	if (!sev_es_negotiate_protocol())
 		sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_PROT_UNSUPPORTED);
 
+	/*
+	 * If SEV-SNP is enabled, then check if the hypervisor supports the SEV-SNP
+	 * features.
+	 */
+	if (sev_snp_enabled() && !(sev_hv_features & GHCB_HV_FT_SNP))
+		sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
+
 	if (set_page_decrypted((unsigned long)&boot_ghcb_page))
 		return false;
 
@@ -174,7 +196,7 @@ void do_boot_stage2_vc(struct pt_regs *regs, unsigned long exit_code)
 	struct es_em_ctxt ctxt;
 	enum es_result result;
 
-	if (!boot_ghcb && !early_setup_sev_es())
+	if (!boot_ghcb && !do_early_sev_setup())
 		sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
 
 	vc_ghcb_invalidate(boot_ghcb);
diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index e75e29c05f59..8abc5eb7ca3d 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -54,6 +54,8 @@
 #define GHCB_MSR_HV_FT_RESP_VAL(v)	\
 	(((unsigned long)((v) >> GHCB_MSR_HV_FT_POS) & GHCB_MSR_HV_FT_MASK))
 
+#define GHCB_HV_FT_SNP			BIT_ULL(0)
+
 #define GHCB_MSR_TERM_REQ		0x100
 #define GHCB_MSR_TERM_REASON_SET_POS	12
 #define GHCB_MSR_TERM_REASON_SET_MASK	0xf
@@ -67,6 +69,7 @@
 #define SEV_TERM_SET_GEN		0
 #define GHCB_SEV_ES_GEN_REQ		0
 #define GHCB_SEV_ES_PROT_UNSUPPORTED	1
+#define GHCB_SNP_UNSUPPORTED		2
 
 #define GHCB_RESP_CODE(v)		((v) & GHCB_MSR_INFO_MASK)
 
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 0245fe986615..504169f1966b 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -665,12 +665,16 @@ static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
  * This function runs on the first #VC exception after the kernel
  * switched to virtual addresses.
  */
-static bool __init sev_es_setup_ghcb(void)
+static bool __init setup_ghcb(void)
 {
 	/* First make sure the hypervisor talks a supported protocol. */
 	if (!sev_es_negotiate_protocol())
 		return false;
 
+	/* If SNP is active, make sure that hypervisor supports the feature. */
+	if (sev_feature_enabled(SEV_SNP) && !(sev_hv_features & GHCB_HV_FT_SNP))
+		sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
+
 	/*
 	 * Clear the boot_ghcb. The first exception comes in before the bss
 	 * section is cleared.
@@ -1479,7 +1483,7 @@ bool __init handle_vc_boot_ghcb(struct pt_regs *regs)
 	enum es_result result;
 
 	/* Do initial setup or terminate the guest */
-	if (unlikely(boot_ghcb == NULL && !sev_es_setup_ghcb()))
+	if (unlikely(boot_ghcb == NULL && !setup_ghcb()))
 		sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
 
 	vc_ghcb_invalidate(boot_ghcb);
-- 
2.17.1


  parent reply	other threads:[~2021-07-07 18:15 UTC|newest]

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-07 18:14 [PATCH Part1 RFC v4 00/36] Add AMD Secure Nested Paging (SEV-SNP) Guest Support Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 01/36] x86/sev: shorten GHCB terminate macro names Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 02/36] x86/sev: Save the negotiated GHCB version Brijesh Singh
2021-08-10  9:17   ` Borislav Petkov
2021-08-10 13:15     ` Brijesh Singh
2021-08-10 10:01   ` Borislav Petkov
2021-08-10 13:17     ` Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 03/36] x86/sev: Add support for hypervisor feature VMGEXIT Brijesh Singh
2021-08-10 11:22   ` Borislav Petkov
2021-08-10 13:39     ` Brijesh Singh
2021-08-10 14:03       ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 04/36] x86/mm: Add sev_feature_enabled() helper Brijesh Singh
2021-07-08  8:50   ` Dr. David Alan Gilbert
2021-07-08  8:53     ` Paolo Bonzini
2021-08-10 11:25   ` Borislav Petkov
2021-08-10 14:57     ` Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 05/36] x86/sev: Define the Linux specific guest termination reasons Brijesh Singh
2021-08-10 11:33   ` Borislav Petkov
2021-08-10 14:59     ` Brijesh Singh
2021-08-10 19:30       ` Tom Lendacky
2021-08-10 21:52         ` Borislav Petkov
2021-07-07 18:14 ` Brijesh Singh [this message]
2021-07-07 18:14 ` [PATCH Part1 RFC v4 07/36] x86/sev: Add a helper for the PVALIDATE instruction Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 08/36] x86/sev: check the vmpl level Brijesh Singh
2021-08-13  7:25   ` Borislav Petkov
2021-08-13 13:13     ` Brijesh Singh
2021-08-13 15:16       ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 09/36] x86/compressed: Add helper for validating pages in the decompression stage Brijesh Singh
2021-08-13 10:22   ` Borislav Petkov
2021-08-13 14:21     ` Brijesh Singh
2021-08-13 15:19       ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 10/36] x86/compressed: Register GHCB memory when SEV-SNP is active Brijesh Singh
2021-08-13 10:47   ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 11/36] x86/sev: " Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 12/36] x86/sev: Add helper for validating pages in early enc attribute changes Brijesh Singh
2021-08-13 11:13   ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 13/36] x86/kernel: Make the bss.decrypted section shared in RMP table Brijesh Singh
2021-08-13 17:09   ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 14/36] x86/kernel: Validate rom memory before accessing when SEV-SNP is active Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 15/36] x86/mm: Add support to validate memory when changing C-bit Brijesh Singh
2021-08-17 17:27   ` Borislav Petkov
2021-08-17 18:07     ` Brijesh Singh
2021-08-17 18:17       ` Borislav Petkov
2021-08-17 18:18         ` Brijesh Singh
2021-08-17 20:34     ` Brijesh Singh
2021-08-17 20:44       ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 16/36] KVM: SVM: define new SEV_FEATURES field in the VMCB Save State Area Brijesh Singh
2021-08-17 17:54   ` Borislav Petkov
2021-08-17 17:59     ` Borislav Petkov
2021-08-17 18:11     ` Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 17/36] KVM: SVM: Create a separate mapping for the SEV-ES save area Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 18/36] KVM: SVM: Create a separate mapping for the GHCB " Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 19/36] KVM: SVM: Update the SEV-ES save area mapping Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 20/36] x86/sev: Use SEV-SNP AP creation to start secondary CPUs Brijesh Singh
2021-08-17 20:04   ` Borislav Petkov
2021-08-17 22:13     ` Tom Lendacky
2021-08-18  8:38       ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 21/36] x86/head/64: set up a startup %gs for stack protector Brijesh Singh
2021-08-19  9:34   ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 22/36] x86/sev: move MSR-based VMGEXITs for CPUID to helper Brijesh Singh
2021-08-19  9:45   ` Borislav Petkov
2021-08-19 15:37     ` Michael Roth
2021-08-19 16:46       ` Borislav Petkov
2021-08-20  3:29         ` Michael Roth
2021-08-23  4:50           ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 23/36] KVM: x86: move lookup of indexed CPUID leafs " Brijesh Singh
2021-08-19 10:07   ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 24/36] x86/compressed/acpi: move EFI config table access to common code Brijesh Singh
2021-08-19 10:47   ` Borislav Petkov
2021-08-19 14:58     ` Michael Roth
2021-08-19 17:09       ` Borislav Petkov
2021-08-19 23:42         ` Michael Roth
2021-08-23  4:52           ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 25/36] x86/boot: Add Confidential Computing type to setup_data Brijesh Singh
2021-08-19 11:06   ` Borislav Petkov
2021-07-07 18:14 ` [PATCH Part1 RFC v4 26/36] x86/compressed/64: enable SEV-SNP-validated CPUID in #VC handler Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 27/36] x86/boot: add a pointer to Confidential Computing blob in bootparams Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 28/36] x86/compressed/64: store Confidential Computing blob address " Brijesh Singh
2021-07-07 18:14 ` [PATCH Part1 RFC v4 29/36] x86/compressed/64: add identity mapping for Confidential Computing blob Brijesh Singh
2021-07-07 18:15 ` [PATCH Part1 RFC v4 30/36] x86/sev: enable SEV-SNP-validated CPUID in #VC handlers Brijesh Singh
2021-07-07 18:15 ` [PATCH Part1 RFC v4 31/36] x86/sev: Provide support for SNP guest request NAEs Brijesh Singh
2021-07-07 18:15 ` [PATCH Part1 RFC v4 32/36] x86/sev: Add snp_msg_seqno() helper Brijesh Singh
2021-07-07 18:15 ` [PATCH Part1 RFC v4 33/36] x86/sev: Register SNP guest request platform device Brijesh Singh
2021-07-07 18:15 ` [PATCH Part1 RFC v4 34/36] virt: Add SEV-SNP guest driver Brijesh Singh
2021-07-07 18:15 ` [PATCH Part1 RFC v4 35/36] virt: sevguest: Add support to derive key Brijesh Singh
2021-07-07 18:15 ` [PATCH Part1 RFC v4 36/36] virt: sevguest: Add support to get extended report Brijesh Singh

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