KVM: VMX: Optimize vmx_get_rflags()

If called several times within the same exit, return cached results.

Signed-off-by: Avi Kivity <avi@redhat.com>

2 files changed, 15 insertions, 6 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c8af0991fdf..5af42646495 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -118,6 +118,7 @@ enum kvm_reg {
 enum kvm_reg_ex {
         VCPU_EXREG_PDPTR = NR_VCPU_REGS,
         VCPU_EXREG_CR3,
+        VCPU_EXREG_RFLAGS,
 };
 
 enum {
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index d09833e45f6..4d117072acf 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -130,6 +130,7 @@ struct vcpu_vmx {
         u8                    fail;
         u32                   exit_intr_info;
         u32                   idt_vectoring_info;
+        ulong                 rflags;
         struct shared_msr_entry *guest_msrs;
         int                   nmsrs;
         int                   save_nmsrs;
@@ -970,17 +971,23 @@ static unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu)
 {
         unsigned long rflags, save_rflags;
 
-        rflags = vmcs_readl(GUEST_RFLAGS);
-        if (to_vmx(vcpu)->rmode.vm86_active) {
-                rflags &= RMODE_GUEST_OWNED_EFLAGS_BITS;
-                save_rflags = to_vmx(vcpu)->rmode.save_rflags;
-                rflags |= save_rflags & ~RMODE_GUEST_OWNED_EFLAGS_BITS;
+        if (!test_bit(VCPU_EXREG_RFLAGS, (ulong *)&vcpu->arch.regs_avail)) {
+                __set_bit(VCPU_EXREG_RFLAGS, (ulong *)&vcpu->arch.regs_avail);
+                rflags = vmcs_readl(GUEST_RFLAGS);
+                if (to_vmx(vcpu)->rmode.vm86_active) {
+                        rflags &= RMODE_GUEST_OWNED_EFLAGS_BITS;
+                        save_rflags = to_vmx(vcpu)->rmode.save_rflags;
+                        rflags |= save_rflags & ~RMODE_GUEST_OWNED_EFLAGS_BITS;
+                }
+                to_vmx(vcpu)->rflags = rflags;
         }
-        return rflags;
+        return to_vmx(vcpu)->rflags;
 }
 
 static void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
 {
+        __set_bit(VCPU_EXREG_RFLAGS, (ulong *)&vcpu->arch.regs_avail);
+        to_vmx(vcpu)->rflags = rflags;
         if (to_vmx(vcpu)->rmode.vm86_active) {
                 to_vmx(vcpu)->rmode.save_rflags = rflags;
                 rflags |= X86_EFLAGS_IOPL | X86_EFLAGS_VM;
@@ -4124,6 +4131,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
               );
 
         vcpu->arch.regs_avail = ~((1 << VCPU_REGS_RIP) | (1 << VCPU_REGS_RSP)
+                                  | (1 << VCPU_EXREG_RFLAGS)
                                   | (1 << VCPU_EXREG_PDPTR)
                                   | (1 << VCPU_EXREG_CR3));
         vcpu->arch.regs_dirty = 0;