Commit Message
Isaku Yamahata
Feb. 26, 2024, 8:26 a.m. UTC
From: Isaku Yamahata <isaku.yamahata@intel.com> When BIOS eMCA MCE-SMI morphing is enabled, the #MC is morphed to MSMI (Machine Check System Management Interrupt). Then the SMI causes TD exit with the read reason of EXIT_REASON_OTHER_SMI with MSMI bit set in the exit qualification to KVM instead of EXIT_REASON_EXCEPTION_NMI with MC exception. Handle EXIT_REASON_OTHER_SMI with MSMI bit set in the exit qualification as MCE(Machine Check Exception) happened during TD guest running. Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com> --- arch/x86/kvm/vmx/tdx.c | 40 ++++++++++++++++++++++++++++++++++--- arch/x86/kvm/vmx/tdx_arch.h | 2 ++ 2 files changed, 39 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index bdd74682b474..117c2315f087 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -916,6 +916,30 @@ void tdx_handle_exit_irqoff(struct kvm_vcpu *vcpu) tdexit_intr_info(vcpu)); else if (exit_reason == EXIT_REASON_EXCEPTION_NMI) vmx_handle_exception_irqoff(vcpu, tdexit_intr_info(vcpu)); + else if (unlikely(tdx->exit_reason.non_recoverable || + tdx->exit_reason.error)) { + /* + * The only reason it gets EXIT_REASON_OTHER_SMI is there is an + * #MSMI(Machine Check System Management Interrupt) with + * exit_qualification bit 0 set in TD guest. + * The #MSMI is delivered right after SEAMCALL returns, + * and an #MC is delivered to host kernel after SMI handler + * returns. + * + * The #MC right after SEAMCALL is fixed up and skipped in #MC + * handler because it's an #MC happens in TD guest we cannot + * handle it with host's context. + * + * Call KVM's machine check handler explicitly here. + */ + if (tdx->exit_reason.basic == EXIT_REASON_OTHER_SMI) { + unsigned long exit_qual; + + exit_qual = tdexit_exit_qual(vcpu); + if (exit_qual & TD_EXIT_OTHER_SMI_IS_MSMI) + kvm_machine_check(); + } + } } static int tdx_handle_exception(struct kvm_vcpu *vcpu) @@ -1381,6 +1405,11 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath) exit_reason.full, exit_reason.basic, to_kvm_tdx(vcpu->kvm)->hkid, set_hkid_to_hpa(0, to_kvm_tdx(vcpu->kvm)->hkid)); + + /* + * tdx_handle_exit_irqoff() handled EXIT_REASON_OTHER_SMI. It + * must be handled before enabling preemption because it's #MC. + */ goto unhandled_exit; } @@ -1419,9 +1448,14 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath) return tdx_handle_ept_misconfig(vcpu); case EXIT_REASON_OTHER_SMI: /* - * If reach here, it's not a Machine Check System Management - * Interrupt(MSMI). #SMI is delivered and handled right after - * SEAMRET, nothing needs to be done in KVM. + * Unlike VMX, all the SMI in SEAM non-root mode (i.e. when + * TD guest vcpu is running) will cause TD exit to TDX module, + * then SEAMRET to KVM. Once it exits to KVM, SMI is delivered + * and handled right away. + * + * - If it's an Machine Check System Management Interrupt + * (MSMI), it's handled above due to non_recoverable bit set. + * - If it's not an MSMI, don't need to do anything here. */ return 1; default: diff --git a/arch/x86/kvm/vmx/tdx_arch.h b/arch/x86/kvm/vmx/tdx_arch.h index efc3c61c14ab..87ef22e9cd49 100644 --- a/arch/x86/kvm/vmx/tdx_arch.h +++ b/arch/x86/kvm/vmx/tdx_arch.h @@ -42,6 +42,8 @@ #define TDH_VP_WR 43 #define TDH_SYS_LP_SHUTDOWN 44 +#define TD_EXIT_OTHER_SMI_IS_MSMI BIT(1) + /* TDX control structure (TDR/TDCS/TDVPS) field access codes */ #define TDX_NON_ARCH BIT_ULL(63) #define TDX_CLASS_SHIFT 56