[PATCH v2 2/5] KVM: X86: Add last guest interrupt disable state support

[Wanpeng Li <kernellwp@gmail.com>]

From: Wanpeng Li <wanpengli@tencent.com>

Let's get the information whether or not guests disable interruptions.
Except preempt_count, interrupt disable can be treated as another in
critical section scenario.

Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
 arch/x86/include/asm/kvm_host.h | 2 ++
 arch/x86/kvm/x86.c              | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c13c9ed50903..7a3eb2ba1d0f 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -857,6 +857,8 @@ struct kvm_vcpu_arch {
 		bool preempt_count_enabled;
 		struct gfn_to_hva_cache preempt_count_cache;
 	} pv_pc;
+	/* guest irq disabled state, valid iff the vCPU is not loaded */
+	bool last_guest_irq_disabled;
 
 	/*
 	 * Indicates the guest is trying to write a gfn that contains one or
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f2d2e3d25230..9aa05f79b743 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4584,6 +4584,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 	static_call(kvm_x86_vcpu_load)(vcpu, cpu);
 
+	vcpu->arch.last_guest_irq_disabled = false;
 	/* Save host pkru register if supported */
 	vcpu->arch.host_pkru = read_pkru();
 
@@ -4676,6 +4677,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 
 	static_call(kvm_x86_vcpu_put)(vcpu);
 	vcpu->arch.last_host_tsc = rdtsc();
+	vcpu->arch.last_guest_irq_disabled = !static_call(kvm_x86_get_if_flag)(vcpu);
 }
 
 static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
@@ -11227,6 +11229,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 	vcpu->arch.pending_external_vector = -1;
 	vcpu->arch.preempted_in_kernel = false;
 	vcpu->arch.pv_pc.preempt_count_enabled = false;
+	vcpu->arch.last_guest_irq_disabled = false;
 
 #if IS_ENABLED(CONFIG_HYPERV)
 	vcpu->arch.hv_root_tdp = INVALID_PAGE;
-- 
2.25.1