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Message-ID: <20211210154332.11526-11-brijesh.singh@amd.com>
Date: Fri, 10 Dec 2021 09:43:02 -0600
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>
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>,
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>,
"Kirill A . Shutemov" <kirill@...temov.name>,
Andi Kleen <ak@...ux.intel.com>,
"Dr . David Alan Gilbert" <dgilbert@...hat.com>,
<tony.luck@...el.com>, <marcorr@...gle.com>,
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH v8 10/40] x86/compressed: Register GHCB memory when SEV-SNP is active
The SEV-SNP guest is required by the GHCB spec to register the GHCB's
Guest Physical Address (GPA). 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 section
"GHCB GPA Registration".
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 | 13 +++++++++++++
arch/x86/kernel/sev-shared.c | 16 ++++++++++++++++
3 files changed, 33 insertions(+)
diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
index 12a93acc94ba..348f7711c3ea 100644
--- a/arch/x86/boot/compressed/sev.c
+++ b/arch/x86/boot/compressed/sev.c
@@ -178,6 +178,10 @@ static bool early_setup_ghcb(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 a2f956cfafba..6dc27963690e 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -57,6 +57,19 @@
#define GHCB_MSR_AP_RESET_HOLD_REQ 0x006
#define GHCB_MSR_AP_RESET_HOLD_RESP 0x007
+/* GHCB GPA Register */
+#define GHCB_MSR_REG_GPA_REQ 0x012
+#define GHCB_MSR_REG_GPA_REQ_VAL(v) \
+ /* GHCBData[63:12] */ \
+ (((u64)((v) & GENMASK_ULL(51, 0)) << 12) | \
+ /* GHCBData[11:0] */ \
+ GHCB_MSR_REG_GPA_REQ)
+
+#define GHCB_MSR_REG_GPA_RESP 0x013
+#define GHCB_MSR_REG_GPA_RESP_VAL(v) \
+ /* GHCBData[63:12] */ \
+ (((u64)(v) & GENMASK_ULL(63, 12)) >> 12)
+
/*
* SNP Page State Change Operation
*
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
index 4a876e684f67..e9ff13cd90b0 100644
--- a/arch/x86/kernel/sev-shared.c
+++ b/arch/x86/kernel/sev-shared.c
@@ -68,6 +68,22 @@ static u64 get_hv_features(void)
return GHCB_MSR_HV_FT_RESP_VAL(val);
}
+static void __maybe_unused snp_register_ghcb_early(unsigned long paddr)
+{
+ unsigned long pfn = paddr >> PAGE_SHIFT;
+ u64 val;
+
+ sev_es_wr_ghcb_msr(GHCB_MSR_REG_GPA_REQ_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_REG_GPA_RESP) ||
+ (GHCB_MSR_REG_GPA_RESP_VAL(val) != pfn))
+ sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_REGISTER);
+}
+
static bool sev_es_negotiate_protocol(void)
{
u64 val;
--
2.25.1
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