linux-kernel - [PATCH v3 2/5] KVM: X86: Introduce need_cancel_enter

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Message-Id: <1587709364-19090-3-git-send-email-wanpengli@tencent.com>
Date:   Fri, 24 Apr 2020 14:22:41 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Haiwei Li <lihaiwei@...cent.com>
Subject: [PATCH v3 2/5] KVM: X86: Introduce need_cancel_enter_guest helper

From: Wanpeng Li <wanpengli@...cent.com>

Introduce need_cancel_enter_guest() helper, we need to check some 
conditions before doing CONT_RUN, in addition, it can also catch 
the case vmexit occurred while another event was being delivered 
to guest software since vmx_complete_interrupts() adds the request 
bit.

Tested-by: Haiwei Li <lihaiwei@...cent.com>
Cc: Haiwei Li <lihaiwei@...cent.com>
Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
---
 arch/x86/kvm/vmx/vmx.c | 12 +++++++-----
 arch/x86/kvm/x86.c     | 10 ++++++++--
 arch/x86/kvm/x86.h     |  1 +
 3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index f1f6638..5c21027 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6577,7 +6577,7 @@ bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
 
 static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
 {
-	enum exit_fastpath_completion exit_fastpath;
+	enum exit_fastpath_completion exit_fastpath = EXIT_FASTPATH_NONE;
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	unsigned long cr3, cr4;
 
@@ -6754,10 +6754,12 @@ static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
 	vmx_recover_nmi_blocking(vmx);
 	vmx_complete_interrupts(vmx);
 
-	exit_fastpath = vmx_exit_handlers_fastpath(vcpu);
-	/* static call is better with retpolines */
-	if (exit_fastpath == EXIT_FASTPATH_CONT_RUN)
-		goto cont_run;
+	if (!kvm_need_cancel_enter_guest(vcpu)) {
+		exit_fastpath = vmx_exit_handlers_fastpath(vcpu);
+		/* static call is better with retpolines */
+		if (exit_fastpath == EXIT_FASTPATH_CONT_RUN)
+			goto cont_run;
+	}
 
 	return exit_fastpath;
 }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 59958ce..4561104 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1581,6 +1581,13 @@ int kvm_emulate_wrmsr(struct kvm_vcpu *vcpu)
 }
 EXPORT_SYMBOL_GPL(kvm_emulate_wrmsr);
 
+bool kvm_need_cancel_enter_guest(struct kvm_vcpu *vcpu)
+{
+	return (vcpu->mode == EXITING_GUEST_MODE || kvm_request_pending(vcpu)
+	    || need_resched() || signal_pending(current));
+}
+EXPORT_SYMBOL_GPL(kvm_need_cancel_enter_guest);
+
 /*
  * The fast path for frequent and performance sensitive wrmsr emulation,
  * i.e. the sending of IPI, sending IPI early in the VM-Exit flow reduces
@@ -8373,8 +8380,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	if (kvm_lapic_enabled(vcpu) && vcpu->arch.apicv_active)
 		kvm_x86_ops.sync_pir_to_irr(vcpu);
 
-	if (vcpu->mode == EXITING_GUEST_MODE || kvm_request_pending(vcpu)
-	    || need_resched() || signal_pending(current)) {
+	if (kvm_need_cancel_enter_guest(vcpu)) {
 		vcpu->mode = OUTSIDE_GUEST_MODE;
 		smp_wmb();
 		local_irq_enable();
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 7b5ed8e..1906e7e 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -364,5 +364,6 @@ static inline bool kvm_dr7_valid(u64 data)
 void kvm_load_guest_xsave_state(struct kvm_vcpu *vcpu);
 void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu);
 u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu);
+bool kvm_need_cancel_enter_guest(struct kvm_vcpu *vcpu);
 
 #endif
-- 
2.7.4