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Date: Fri, 28 Jan 2022 11:17:30 -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>, <brijesh.ksingh@...il.com>, <tony.luck@...el.com>, <marcorr@...gle.com>, <sathyanarayanan.kuppuswamy@...ux.intel.com>, Brijesh Singh <brijesh.singh@....com>, Venu Busireddy <venu.busireddy@...cle.com> Subject: [PATCH v9 09/43] x86/sev: Save the negotiated GHCB version The SEV-ES guest calls the sev_es_negotiate_protocol() to negotiate the GHCB protocol version before establishing the GHCB. Cache the negotiated GHCB version so that it can be used later. Reviewed-by: Venu Busireddy <venu.busireddy@...cle.com> Signed-off-by: Brijesh Singh <brijesh.singh@....com> --- arch/x86/include/asm/sev.h | 2 +- arch/x86/kernel/sev-shared.c | 17 ++++++++++++++--- 2 files changed, 15 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index ec060c433589..9b9c190e8c3b 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -12,7 +12,7 @@ #include <asm/insn.h> #include <asm/sev-common.h> -#define GHCB_PROTO_OUR 0x0001UL +#define GHCB_PROTOCOL_MIN 1ULL #define GHCB_PROTOCOL_MAX 1ULL #define GHCB_DEFAULT_USAGE 0ULL diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index 2abf8a7d75e5..91105f5a02a8 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -14,6 +14,15 @@ #define has_cpuflag(f) boot_cpu_has(f) #endif +/* + * Since feature negotiation related variables are set early in the boot + * process they must reside in the .data section so as not to be zeroed + * out when the .bss section is later cleared. + * + * GHCB protocol version negotiated with the hypervisor. + */ +static u16 ghcb_version __ro_after_init; + static bool __init sev_es_check_cpu_features(void) { if (!has_cpuflag(X86_FEATURE_RDRAND)) { @@ -51,10 +60,12 @@ static bool sev_es_negotiate_protocol(void) if (GHCB_MSR_INFO(val) != GHCB_MSR_SEV_INFO_RESP) return false; - if (GHCB_MSR_PROTO_MAX(val) < GHCB_PROTO_OUR || - GHCB_MSR_PROTO_MIN(val) > GHCB_PROTO_OUR) + if (GHCB_MSR_PROTO_MAX(val) < GHCB_PROTOCOL_MIN || + GHCB_MSR_PROTO_MIN(val) > GHCB_PROTOCOL_MAX) return false; + ghcb_version = min_t(size_t, GHCB_MSR_PROTO_MAX(val), GHCB_PROTOCOL_MAX); + return true; } @@ -127,7 +138,7 @@ enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, bool set_ghcb_msr, u64 exit_info_1, u64 exit_info_2) { /* Fill in protocol and format specifiers */ - ghcb->protocol_version = GHCB_PROTOCOL_MAX; + ghcb->protocol_version = ghcb_version; ghcb->ghcb_usage = GHCB_DEFAULT_USAGE; ghcb_set_sw_exit_code(ghcb, exit_code); -- 2.25.1
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