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Date: Wed, 7 Jul 2021 13:14:40 -0500
From: Brijesh Singh <brijesh.singh@....com>
To: x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
linux-coco@...ts.linux.dev, linux-mm@...ck.org,
linux-crypto@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
Tom Lendacky <thomas.lendacky@....com>,
"H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <seanjc@...gle.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Andy Lutomirski <luto@...nel.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
Peter Zijlstra <peterz@...radead.org>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
David Rientjes <rientjes@...gle.com>,
Dov Murik <dovmurik@...ux.ibm.com>,
Tobin Feldman-Fitzthum <tobin@....com>,
Borislav Petkov <bp@...en8.de>,
Michael Roth <michael.roth@....com>,
Vlastimil Babka <vbabka@...e.cz>, tony.luck@...el.com,
npmccallum@...hat.com, brijesh.ksingh@...il.com,
Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH Part1 RFC v4 10/36] x86/compressed: Register GHCB memory when SEV-SNP is active
The SEV-SNP guest is required to perform GHCB GPA registration. This is
because the hypervisor may prefer that a guest use a consistent and/or
specific GPA for the GHCB associated with a vCPU. For more information,
see the GHCB specification.
If hypervisor can not work with the guest provided GPA then terminate the
guest boot.
Signed-off-by: Brijesh Singh <brijesh.singh@....com>
---
arch/x86/boot/compressed/sev.c | 4 ++++
arch/x86/include/asm/sev-common.h | 11 +++++++++++
arch/x86/kernel/sev-shared.c | 16 ++++++++++++++++
3 files changed, 31 insertions(+)
diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
index f386d45a57b6..d4cbadf80838 100644
--- a/arch/x86/boot/compressed/sev.c
+++ b/arch/x86/boot/compressed/sev.c
@@ -233,6 +233,10 @@ static bool do_early_sev_setup(void)
/* Initialize lookup tables for the instruction decoder */
inat_init_tables();
+ /* SEV-SNP guest requires the GHCB GPA must be registered */
+ if (sev_snp_enabled())
+ snp_register_ghcb_early(__pa(&boot_ghcb_page));
+
return true;
}
diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index aee07d1bb138..b19d8d301f5d 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -45,6 +45,17 @@
(((unsigned long)reg & GHCB_MSR_CPUID_REG_MASK) << GHCB_MSR_CPUID_REG_POS) | \
(((unsigned long)fn) << GHCB_MSR_CPUID_FUNC_POS))
+/* GHCB GPA Register */
+#define GHCB_MSR_GPA_REG_REQ 0x012
+#define GHCB_MSR_GPA_REG_VALUE_POS 12
+#define GHCB_MSR_GPA_REG_GFN_MASK GENMASK_ULL(51, 0)
+#define GHCB_MSR_GPA_REQ_GFN_VAL(v) \
+ (((unsigned long)((v) & GHCB_MSR_GPA_REG_GFN_MASK) << GHCB_MSR_GPA_REG_VALUE_POS)| \
+ GHCB_MSR_GPA_REG_REQ)
+
+#define GHCB_MSR_GPA_REG_RESP 0x013
+#define GHCB_MSR_GPA_REG_RESP_VAL(v) ((v) >> GHCB_MSR_GPA_REG_VALUE_POS)
+
/* SNP Page State Change */
#define GHCB_MSR_PSC_REQ 0x014
#define SNP_PAGE_STATE_PRIVATE 1
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
index c54be2698df0..be4025f14b4f 100644
--- a/arch/x86/kernel/sev-shared.c
+++ b/arch/x86/kernel/sev-shared.c
@@ -67,6 +67,22 @@ static bool get_hv_features(void)
return true;
}
+static void snp_register_ghcb_early(unsigned long paddr)
+{
+ unsigned long pfn = paddr >> PAGE_SHIFT;
+ u64 val;
+
+ sev_es_wr_ghcb_msr(GHCB_MSR_GPA_REQ_GFN_VAL(pfn));
+ VMGEXIT();
+
+ val = sev_es_rd_ghcb_msr();
+
+ /* If the response GPA is not ours then abort the guest */
+ if ((GHCB_RESP_CODE(val) != GHCB_MSR_GPA_REG_RESP) ||
+ (GHCB_MSR_GPA_REG_RESP_VAL(val) != pfn))
+ sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_REGISTER);
+}
+
static bool sev_es_negotiate_protocol(void)
{
u64 val;
--
2.17.1
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