• Sean Christopherson's avatar
    KVM: VMX: Fix handling of #MC that occurs during VM-Entry · 891011ca
    Sean Christopherson authored
    [ Upstream commit beb8d93b ]
    
    A previous fix to prevent KVM from consuming stale VMCS state after a
    failed VM-Entry inadvertantly blocked KVM's handling of machine checks
    that occur during VM-Entry.
    
    Per Intel's SDM, a #MC during VM-Entry is handled in one of three ways,
    depending on when the #MC is recognoized.  As it pertains to this bug
    fix, the third case explicitly states EXIT_REASON_MCE_DURING_VMENTRY
    is handled like any other VM-Exit during VM-Entry, i.e. sets bit 31 to
    indicate the VM-Entry failed.
    
    If a machine-check event occurs during a VM entry, one of the following occurs:
     - The machine-check event is handled as if it occurred before the VM entry:
            ...
     - The machine-check event is handled after VM entry completes:
            ...
     - A VM-entry failure occurs as described in Section 26.7. The basic
       exit reason is 41, for "VM-entry failure due to machine-check event".
    
    Explicitly handle EXIT_REASON_MCE_DURING_VMENTRY as a one-off case in
    vmx_vcpu_run() instead of binning it into vmx_complete_atomic_exit().
    Doing so allows vmx_vcpu_run() to handle VMX_EXIT_REASONS_FAILED_VMENTRY
    in a sane fashion and also simplifies vmx_complete_atomic_exit() since
    VMCS.VM_EXIT_INTR_INFO is guaranteed to be fresh.
    
    Fixes: b060ca3b ("kvm: vmx: Handle VMLAUNCH/VMRESUME failure properly")
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
    Reviewed-by: default avatarJim Mattson <jmattson@google.com>
    Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
    891011ca
vmx.c 410 KB