From: Joerg Roedel <[email protected]> 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 <[email protected]> --- arch/x86/include/asm/sev.h | 4 ++-- arch/x86/kernel/sev-shared.c | 36 ++++++++++++++++++++++++++++++++++-- arch/x86/kernel/sev.c | 8 ++++++++ 3 files changed, 44 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index ec060c433589..17b75f6ee11a 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -12,8 +12,8 @@ #include <asm/insn.h> #include <asm/sev-common.h> -#define GHCB_PROTO_OUR 0x0001UL -#define GHCB_PROTOCOL_MAX 1ULL +#define GHCB_PROTOCOL_MIN 1ULL +#define GHCB_PROTOCOL_MAX 2ULL #define GHCB_DEFAULT_USAGE 0ULL #define VMGEXIT() { asm volatile("rep; vmmcall\n\r"); } diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index ce987688bbc0..60ca7dd64d64 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -14,6 +14,23 @@ #define has_cpuflag(f) boot_cpu_has(f) #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; + static bool __init sev_es_check_cpu_features(void) { if (!has_cpuflag(X86_FEATURE_RDRAND)) { @@ -44,6 +61,7 @@ static void __noreturn sev_es_terminate(unsigned int reason) static bool sev_es_negotiate_protocol(void) { + unsigned int protocol; u64 val; /* Do the GHCB protocol version negotiation */ @@ -54,10 +72,24 @@ 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_PROTO_OUR || - GHCB_MSR_PROTO_MIN(val) > GHCB_PROTO_OUR) + /* Sanity check untrusted input */ + if (GHCB_MSR_PROTO_MIN(val) > GHCB_MSR_PROTO_MAX(val)) return false; + /* Use maximum supported protocol version */ + protocol = min_t(unsigned int, GHCB_MSR_PROTO_MAX(val), GHCB_PROTOCOL_MAX); + + /* + * Hypervisor does not support any protocol version required for this + * kernel. + */ + if (protocol < 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 = protocol; + return true; } diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index e6d316a01fdd..8a4317fa699a 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -779,6 +779,14 @@ 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 _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
