KVM: VMX: Enable MSR-BASED TPR shadow even if APICv is inactive
I observed that kvmvapic(to optimize flexpriority=N or AMD) is used to boost TPR access when testing kvm-unit-test/eventinj.flat tpr case on my haswell desktop (w/ flexpriority, w/o APICv). Commit (8d14695f x86, apicv: add virtual x2apic support) disable virtual x2apic mode completely if w/o APICv, and the author also told me that windows guest can't enter into x2apic mode when he developed the APICv feature several years ago. However, it is not truth currently, Interrupt Remapping and vIOMMU is added to qemu and the developers from Intel test windows 8 can work in x2apic mode w/ Interrupt Remapping enabled recently. This patch enables TPR shadow for virtual x2apic mode to boost windows guest in x2apic mode even if w/o APICv. Can pass the kvm-unit-test. Suggested-by: Radim Krčmář <rkrcmar@redhat.com> Suggested-by: Wincy Van <fanwenyi0529@gmail.com> Reviewed-by: Radim Krčmář <rkrcmar@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Wincy Van <fanwenyi0529@gmail.com> Cc: Yang Zhang <yang.zhang.wz@gmail.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Showing
Please register or sign in to comment