| Message ID | 1440925898-23440-3-git-send-email-mst@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 8e0c084..6422fac 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1812,6 +1812,11 @@ static int pf_interception(struct vcpu_svm *svm) switch (svm->apf_reason) { default: error_code = svm->vmcb->control.exit_info_1; + if (!kvm_io_bus_write(&svm->vcpu, KVM_FAST_MMIO_BUS, + fault_address, 0, NULL)) { + skip_emulated_instruction(&svm->vcpu); + return 1; + } trace_kvm_page_fault(fault_address, error_code); if (!npt_enabled && kvm_event_needs_reinjection(&svm->vcpu))
MMIO is slightly slower than port IO because it uses the page-tables, so the CPU must do a pagewalk on each access. This overhead is normally masked by using the TLB cache: but not so for KVM MMIO, where PTEs are marked as reserved and so are never cached. As ioeventfd memory is never read, make it possible to use RO pages on the host for ioeventfds, instead. The result is that TLBs are cached, which finally makes MMIO as fast as port IO. Warning: untested. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- arch/x86/kvm/svm.c | 5 +++++ 1 file changed, 5 insertions(+)