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Mon, 10 Jun 2024 03:21:27 -0700 (PDT) Received: from vasant-suse.fritz.box ([2001:9e8:ab68:af00:6f43:17ee:43bd:e0a9]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a6f0d7b35d5sm290887766b.192.2024.06.10.03.21.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Jun 2024 03:21:26 -0700 (PDT) From: vsntk18@gmail.com To: vsntk18@gmail.com Cc: x86@kernel.org, Borislav.Petkov@amd.com, Dhaval.Giani@amd.com, ashish.kalra@amd.com, cfir@google.com, dan.j.williams@intel.com, dave.hansen@linux.intel.com, ebiederm@xmission.com, erdemaktas@google.com, hpa@zytor.com, jgross@suse.com, jroedel@suse.de, jslaby@suse.cz, keescook@chromium.org, kexec@lists.infradead.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, luto@kernel.org, martin.b.radev@gmail.com, mhiramat@kernel.org, michael.roth@amd.com, mstunes@vmware.com, nivedita@alum.mit.edu, peterz@infradead.org, rientjes@google.com, seanjc@google.com, stable@vger.kernel.org, thomas.lendacky@amd.com, virtualization@lists.linux-foundation.org, vkarasulli@suse.de Subject: [PATCH v6 02/10] x86/sev: Save and print negotiated GHCB protocol version Date: Mon, 10 Jun 2024 12:21:05 +0200 Message-Id: <20240610102113.20969-3-vsntk18@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240610102113.20969-1-vsntk18@gmail.com> References: <20240610102113.20969-1-vsntk18@gmail.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Joerg Roedel Save the results of the GHCB protocol negotiation into a data structure and print information about versions supported and used to the kernel log. This is useful for debugging kexec issues in SEV-ES guests down the road to quickly spot whether kexec is supported on the given host. Signed-off-by: Joerg Roedel Signed-off-by: Vasant Karasulli --- arch/x86/kernel/sev-shared.c | 33 +++++++++++++++++++++++++++++++-- arch/x86/kernel/sev.c | 8 ++++++++ 2 files changed, 39 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index b4f8fa0f722c..f5717eddf75b 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -23,6 +23,23 @@ #define sev_printk_rtl(fmt, ...) #endif +/* + * struct ghcb_info - Used to return GHCB protocol + * negotiation details. + * + * @hv_proto_min: Minimum GHCB protocol version supported by Hypervisor + * @hv_proto_max: Maximum GHCB protocol version supported by Hypervisor + * @vm_proto: Protocol version the VM (this kernel) will use + */ +struct ghcb_info { + unsigned int hv_proto_min; + unsigned int hv_proto_max; + unsigned int vm_proto; +}; + +/* Negotiated GHCB protocol version */ +static struct ghcb_info ghcb_info __ro_after_init; + /* I/O parameters for CPUID-related helpers */ struct cpuid_leaf { u32 fn; @@ -159,12 +176,24 @@ 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_PROTOCOL_MIN || - GHCB_MSR_PROTO_MIN(val) > GHCB_PROTOCOL_MAX) + /* Sanity check untrusted input */ + if (GHCB_MSR_PROTO_MIN(val) > GHCB_MSR_PROTO_MAX(val)) return false; + /* Use maximum supported protocol version */ ghcb_version = min_t(size_t, GHCB_MSR_PROTO_MAX(val), GHCB_PROTOCOL_MAX); + /* + * Hypervisor does not support any protocol version required for this + * kernel. + */ + if (ghcb_version < GHCB_MSR_PROTO_MIN(val)) + return false; + + ghcb_info.hv_proto_min = GHCB_MSR_PROTO_MIN(val); + ghcb_info.hv_proto_max = GHCB_MSR_PROTO_MAX(val); + ghcb_info.vm_proto = ghcb_version; + return true; } diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 3342ed58e168..f0d87549b1e1 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -1399,6 +1399,14 @@ void __init sev_es_init_vc_handling(void) /* Secondary CPUs use the runtime #VC handler */ initial_vc_handler = (unsigned long)kernel_exc_vmm_communication; + + /* + * Print information about supported and negotiated GHCB protocol + * versions. + */ + pr_info("Hypervisor GHCB protocol version support: min=%u max=%u\n", + ghcb_info.hv_proto_min, ghcb_info.hv_proto_max); + pr_info("Using GHCB protocol version %u\n", ghcb_info.vm_proto); } static void __init vc_early_forward_exception(struct es_em_ctxt *ctxt) -- 2.34.1