[PATCH 5/5] KVM: VMX: Handle NMIs, #MCs and async #PFs in common irqs-disabled fn

From: Sean Christopherson <sean.j.christopherson@intel.com>
To: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Joerg Roedel" <joro@8bytes.org>
Cc: kvm@vger.kernel.org, Jim Mattson <jmattson@google.com>
Subject: [PATCH 5/5] KVM: VMX: Handle NMIs, #MCs and async #PFs in common irqs-disabled fn
Date: Fri, 19 Apr 2019 22:50:59 -0700	[thread overview]
Message-ID: <20190420055059.16816-6-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20190420055059.16816-1-sean.j.christopherson@intel.com>

Per commit 1b6269db3f833 ("KVM: VMX: Handle NMIs before enabling
interrupts and preemption"), NMIs are handled directly in vmx_vcpu_run()
to "make sure we handle NMI on the current cpu, and that we don't
service maskable interrupts before non-maskable ones".  The other
exceptions handled by complete_atomic_exit(), e.g. async #PF and #MC,
have similar requirements, and are located there to avoid extra VMREADs
since VMX bins hardware exceptions and NMIs into a single exit reason.

Clean up the code and eliminate the vaguely named complete_atomic_exit()
by moving the interrupts-disabled exception and NMI handling into the
existing handle_external_intrs() callback, and rename the callback to
a more appropriate name.

In addition to improving code readability, this also ensures the NMI
handler is run with the host's debug registers loaded in the unlikely
event that the user is debugging NMIs.  Accuracy of the last_guest_tsc
field is also improved when handling NMIs (and #MCs) as the handler
will run after updating said field.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/include/asm/kvm_host.h |  2 +-
 arch/x86/kvm/svm.c              |  4 ++--
 arch/x86/kvm/vmx/vmx.c          | 25 ++++++++++++++-----------
 arch/x86/kvm/x86.c              |  2 +-
 4 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 8d68ba0cba0c..cd60c3ae7f66 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1109,7 +1109,7 @@ struct kvm_x86_ops {
 	int (*check_intercept)(struct kvm_vcpu *vcpu,
 			       struct x86_instruction_info *info,
 			       enum x86_intercept_stage stage);
-	void (*handle_external_intr)(struct kvm_vcpu *vcpu);
+	void (*handle_events_irqs_disabled)(struct kvm_vcpu *vcpu);
 	bool (*mpx_supported)(void);
 	bool (*xsaves_supported)(void);
 	bool (*umip_emulated)(void);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 38e1c7d382a1..e117058eba87 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6160,7 +6160,7 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu,
 	return ret;
 }
 
-static void svm_handle_external_intr(struct kvm_vcpu *vcpu)
+static void svm_handle_events_irqs_disabled(struct kvm_vcpu *vcpu)
 {
 	kvm_before_interrupt(vcpu);
 	local_irq_enable();
@@ -7256,7 +7256,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
 	.set_tdp_cr3 = set_tdp_cr3,
 
 	.check_intercept = svm_check_intercept,
-	.handle_external_intr = svm_handle_external_intr,
+	.handle_events_irqs_disabled = svm_handle_events_irqs_disabled,
 
 	.request_immediate_exit = __kvm_request_immediate_exit,
 
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 1fbd5a5dd6af..9b580749217f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4441,7 +4441,7 @@ static void kvm_machine_check(void)
 
 static int handle_machine_check(struct kvm_vcpu *vcpu)
 {
-	/* already handled by vcpu_run */
+	/* handled by vmx_handle_events_irqs_disabled() */
 	return 1;
 }
 
@@ -4461,7 +4461,7 @@ static int handle_exception(struct kvm_vcpu *vcpu)
 		return handle_machine_check(vcpu);
 
 	if (is_nmi(intr_info))
-		return 1;  /* already handled by vmx_vcpu_run() */
+		return 1; /* handled by vmx_handle_events_irqs_disabled() */
 
 	if (is_invalid_opcode(intr_info))
 		return handle_ud(vcpu);
@@ -6099,11 +6099,8 @@ static void vmx_apicv_post_state_restore(struct kvm_vcpu *vcpu)
 	memset(vmx->pi_desc.pir, 0, sizeof(vmx->pi_desc.pir));
 }
 
-static void vmx_complete_atomic_exit(struct vcpu_vmx *vmx)
+static void vmx_handle_exception_nmi_irqs_disabled(struct vcpu_vmx *vmx)
 {
-	if (vmx->exit_reason != EXIT_REASON_EXCEPTION_NMI)
-		return;
-
 	vmx->exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
 
 	/* if exit due to PF check for async PF */
@@ -6131,9 +6128,6 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu)
 #endif
 	u32 intr_info;
 
-	if (to_vmx(vcpu)->exit_reason != EXIT_REASON_EXTERNAL_INTERRUPT)
-		return;
-
 	intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
 	if (WARN_ONCE(!is_external_intr(intr_info),
 	    "KVM: unexpected VM-Exit interrupt info: 0x%x", intr_info))
@@ -6169,6 +6163,16 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu)
 }
 STACK_FRAME_NON_STANDARD(vmx_handle_external_intr);
 
+static void vmx_handle_events_irqs_disabled(struct kvm_vcpu *vcpu)
+{
+	struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+	if (vmx->exit_reason == EXIT_REASON_EXCEPTION_NMI)
+		vmx_handle_exception_nmi_irqs_disabled(vmx);
+	else if (vmx->exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
+		vmx_handle_external_intr(vcpu);
+}
+
 static bool vmx_has_emulated_msr(int index)
 {
 	switch (index) {
@@ -6533,7 +6537,6 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
 	vmx->loaded_vmcs->launched = 1;
 	vmx->idt_vectoring_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
 
-	vmx_complete_atomic_exit(vmx);
 	vmx_recover_nmi_blocking(vmx);
 	vmx_complete_interrupts(vmx);
 }
@@ -7708,7 +7711,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
 	.set_tdp_cr3 = vmx_set_cr3,
 
 	.check_intercept = vmx_check_intercept,
-	.handle_external_intr = vmx_handle_external_intr,
+	.handle_events_irqs_disabled = vmx_handle_events_irqs_disabled,
 	.mpx_supported = vmx_mpx_supported,
 	.xsaves_supported = vmx_xsaves_supported,
 	.umip_emulated = vmx_umip_emulated,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7aa002b12f25..82d320f42b1d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7945,7 +7945,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	vcpu->mode = OUTSIDE_GUEST_MODE;
 	smp_wmb();
 
-	kvm_x86_ops->handle_external_intr(vcpu);
+	kvm_x86_ops->handle_events_irqs_disabled(vcpu);
 
 	++vcpu->stat.exits;
 
-- 
2.21.0

