[PATCH v6 4/4] KVM: X86: Add flush_on_enter before guest enter

[Wanpeng Li <kernellwp@gmail.com>]

From: Wanpeng Li <wanpeng.li@hotmail.com>

PV-Flush guest would indicate to flush on enter, flush the TLB before
entering the guest.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
 arch/x86/kvm/cpuid.c |  3 ++-
 arch/x86/kvm/x86.c   | 21 ++++++++++++++-------
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index b943711..8834898 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -601,7 +601,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 			     (1 << KVM_FEATURE_ASYNC_PF) |
 			     (1 << KVM_FEATURE_PV_EOI) |
 			     (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
-			     (1 << KVM_FEATURE_PV_UNHALT);
+			     (1 << KVM_FEATURE_PV_UNHALT) |
+			     (1 << KVM_FEATURE_PV_TLB_FLUSH);
 
 		if (sched_info_on())
 			entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c279530..94c23ae 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2121,6 +2121,12 @@ static void kvmclock_reset(struct kvm_vcpu *vcpu)
 	vcpu->arch.pv_time_enabled = false;
 }
 
+static void kvm_vcpu_flush_tlb(struct kvm_vcpu *vcpu, bool invalidate_gpa)
+{
+	++vcpu->stat.tlb_flush;
+	kvm_x86_ops->tlb_flush(vcpu, invalidate_gpa);
+}
+
 static void record_steal_time(struct kvm_vcpu *vcpu)
 {
 	if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED))
@@ -2130,7 +2136,14 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
 		&vcpu->arch.st.steal, sizeof(struct kvm_steal_time))))
 		return;
 
-	vcpu->arch.st.steal.preempted = KVM_VCPU_NOT_PREEMPTED;
+	if (xchg(&vcpu->arch.st.steal.preempted, KVM_VCPU_NOT_PREEMPTED) ==
+			(KVM_VCPU_SHOULD_FLUSH | KVM_VCPU_PREEMPTED)) {
+		/*
+		 * Do TLB_FLUSH before entering the guest, its passed
+		 * the stage of request checking
+		 */
+		kvm_vcpu_flush_tlb(vcpu, false);
+	}
 
 	if (vcpu->arch.st.steal.version & 1)
 		vcpu->arch.st.steal.version += 1;  /* first time write, random junk */
@@ -6775,12 +6788,6 @@ static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)
 	kvm_x86_ops->load_eoi_exitmap(vcpu, eoi_exit_bitmap);
 }
 
-static void kvm_vcpu_flush_tlb(struct kvm_vcpu *vcpu, bool invalidate_gpa)
-{
-	++vcpu->stat.tlb_flush;
-	kvm_x86_ops->tlb_flush(vcpu, invalidate_gpa);
-}
-
 void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
 {
 	struct page *page = NULL;
-- 
2.7.4