From: Joerg Roedel jroedel@suse.de
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 jroedel@suse.de Signed-off-by: Vasant Karasulli vkarasulli@suse.de --- 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)