KVM: VMX: Skip VMCLEAR logic during emergency reboots if CR4.VMXE=0

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Bail from vmx_emergency_disable() without processing the list of loaded
VMCSes if CR4.VMXE=0, i.e. if the CPU can't be post-VMXON.  It should be
impossible for the list to have entries if VMX is already disabled, and
even if that invariant doesn't hold, VMCLEAR will #UD anyways, i.e.
processing the list is pointless even if it somehow isn't empty.

Assuming no existing KVM bugs, this should be a glorified nop.  The
primary motivation for the change is to avoid having code that looks like
it does VMCLEAR, but then skips VMXON, which is nonsensical.

Suggested-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20230721201859.2307736-20-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

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This commit is contained in:

Sean Christopherson 2023-07-21 13:18:59 -07:00

parent 2e6b9bd49b

commit a788fbb763

1 changed files with 10 additions and 2 deletions

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arch/x86/kvm/vmx/vmx.c

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