KVM: x86: Reject loading KVM if host.PAT[0] != WB

Reject KVM if entry '0' in the host's IA32_PAT MSR is not programmed to
writeback (WB) memtype.  KVM subtly relies on IA32_PAT entry '0' to be
programmed to WB by leaving the PAT bits in shadow paging and NPT SPTEs
as '0'.  If something other than WB is in PAT[0], at _best_ guests will
suffer very poor performance, and at worst KVM will crash the system by
breaking cache-coherency expecations (e.g. using WC for guest memory).

Signed-off-by: Sean Christopherson <[email protected]>
Reviewed-by: Maxim Levitsky <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

0 files changed, 0 insertions, 0 deletions