On Thu, Jun 13, 2019 at 10:03 AM Paolo Bonzini pbonzini@redhat.com wrote:
From: Sean Christopherson sean.j.christopherson@intel.com
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: b060ca3b2e9e7 ("kvm: vmx: Handle VMLAUNCH/VMRESUME failure properly")
I'm never going to live down that subject line, am I? :-)
Reviewed-by: Jim Mattson jmattson@google.com