x86: kvm: Add MTRR support for kvm_get|put_msrs()
The MTRR state in KVM currently runs completely independent of the QEMU state in CPUX86State.mtrr_*. This means that on migration, the target loses MTRR state from the source. Generally that's ok though because KVM ignores it and maps everything as write-back anyway. The exception to this rule is when we have an assigned device and an IOMMU that doesn't promote NoSnoop transactions from that device to be cache coherent. In that case KVM trusts the guest mapping of memory as configured in the MTRR. This patch updates kvm_get|put_msrs() so that we retrieve the actual vCPU MTRR settings and therefore keep CPUX86State synchronized for migration. kvm_put_msrs() is also used on vCPU reset and therefore allows future modificaitons of MTRR state at reset to be realized. Note that the entries array used by both functions was already slightly undersized for holding every possible MSR, so this patch increases it beyond the 28 new entries necessary for MTRR state. Signed-off-by: NAlex Williamson <alex.williamson@redhat.com> Reviewed-by: NLaszlo Ersek <lersek@redhat.com> Cc: qemu-stable@nongnu.org Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com> (cherry picked from commit d1ae67f6) Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
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