From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
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 (8d14695f9542
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: Wincy Van <fanwenyi0529@xxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Cc: Wincy Van <fanwenyi0529@xxxxxxxxx>
Cc: Yang Zhang <yang.zhang.wz@xxxxxxxxx>
Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
---
v1 -> v2:
* leverage the cached msr bitmap
arch/x86/kvm/vmx.c | 35 ++++++++++++++++++-----------------
1 file changed, 18 insertions(+), 17 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 5cede40..7d884e1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6464,17 +6464,23 @@ static __init int hardware_setup(void)
set_bit(0, vmx_vpid_bitmap); /* 0 is reserved for host */
- for (msr = 0x800; msr <= 0x8ff; msr++)
- vmx_disable_intercept_msr_read_x2apic(msr);
-
- /* TMCCT */
- vmx_enable_intercept_msr_read_x2apic(0x839);
- /* TPR */
- vmx_disable_intercept_msr_write_x2apic(0x808);
- /* EOI */
- vmx_disable_intercept_msr_write_x2apic(0x80b);
- /* SELF-IPI */
- vmx_disable_intercept_msr_write_x2apic(0x83f);
+ if (enable_apicv) {
+ for (msr = 0x800; msr <= 0x8ff; msr++)
+ vmx_disable_intercept_msr_read_x2apic(msr);
+
+ /* TMCCT */
+ vmx_enable_intercept_msr_read_x2apic(0x839);
+ /* TPR */
+ vmx_disable_intercept_msr_write_x2apic(0x808);
+ /* EOI */
+ vmx_disable_intercept_msr_write_x2apic(0x80b);
+ /* SELF-IPI */
+ vmx_disable_intercept_msr_write_x2apic(0x83f);
+ } else if (cpu_has_vmx_tpr_shadow()) {
+ /* TPR */
+ vmx_disable_intercept_msr_read_x2apic(0x808);
+ vmx_disable_intercept_msr_write_x2apic(0x808);
+ }
if (enable_ept) {
kvm_mmu_set_mask_ptes(VMX_EPT_READABLE_MASK,
@@ -8435,12 +8441,7 @@ static void vmx_set_virtual_x2apic_mode(struct kvm_vcpu *vcpu, bool set)
return;
}
- /*
- * There is not point to enable virtualize x2apic without enable
- * apicv
- */
- if (!cpu_has_vmx_virtualize_x2apic_mode() ||
- !kvm_vcpu_apicv_active(vcpu))
+ if (!cpu_has_vmx_virtualize_x2apic_mode())
return;
if (!cpu_need_tpr_shadow(vcpu))
--
1.9.1
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