linux-kernel - [PATCH 3/4] KVM: async_pf: Force a nested vmexit if the injected #PF is async

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Date:   Mon, 12 Jun 2017 23:08:13 -0700
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: [PATCH 3/4] KVM: async_pf: Force a nested vmexit if the injected #PF is async_pf

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

Add an async_page_fault field to vcpu->arch.exception to identify an async 
page fault, and constructs the expected vm-exit information fields. Force 
a nested VM exit from nested_vmx_check_exception() if the injected #PF 
is async page fault.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
---
 arch/x86/include/asm/kvm_emulate.h |  1 +
 arch/x86/include/asm/kvm_host.h    |  1 +
 arch/x86/kvm/vmx.c                 | 21 ++++++++++++++++++---
 arch/x86/kvm/x86.c                 |  3 +++
 4 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 0559626..b5bcad9 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -23,6 +23,7 @@ struct x86_exception {
 	u16 error_code;
 	bool nested_page_fault;
 	u64 address; /* cr2 or nested page fault gpa */
+	bool async_page_fault;
 };
 
 /*
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1f01bfb..d30576a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -545,6 +545,7 @@ struct kvm_vcpu_arch {
 		bool reinject;
 		u8 nr;
 		u32 error_code;
+		bool async_page_fault;
 	} exception;
 
 	struct kvm_queued_interrupt {
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f533cc1..da81e48 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2422,13 +2422,28 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
 static int nested_vmx_check_exception(struct kvm_vcpu *vcpu, unsigned nr)
 {
 	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
+	u32 intr_info = 0;
+	unsigned long exit_qualification = 0;
 
-	if (!(vmcs12->exception_bitmap & (1u << nr)))
+	if (!((vmcs12->exception_bitmap & (1u << nr)) ||
+		(nr == PF_VECTOR && vcpu->arch.exception.async_page_fault)))
 		return 0;
 
+	intr_info = nr | INTR_INFO_VALID_MASK;
+	exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
+	if (vcpu->arch.exception.has_error_code) {
+		vmcs_write32(VM_EXIT_INTR_ERROR_CODE, vcpu->arch.exception.error_code);
+		intr_info |= INTR_INFO_DELIVER_CODE_MASK;
+	}
+	if (kvm_exception_is_soft(nr))
+		intr_info |= INTR_TYPE_SOFT_EXCEPTION;
+	else
+		intr_info |= INTR_TYPE_HARD_EXCEPTION;
+	if (nr == PF_VECTOR && vcpu->arch.exception.async_page_fault)
+		exit_qualification = vcpu->arch.cr2;
+
 	nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI,
-			  vmcs_read32(VM_EXIT_INTR_INFO),
-			  vmcs_readl(EXIT_QUALIFICATION));
+			intr_info, exit_qualification);
 	return 1;
 }
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1b28a31..d7f1a49 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -453,6 +453,7 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault)
 {
 	++vcpu->stat.pf_guest;
 	vcpu->arch.cr2 = fault->address;
+	vcpu->arch.exception.async_page_fault = fault->async_page_fault;
 	kvm_queue_exception_e(vcpu, PF_VECTOR, fault->error_code);
 }
 EXPORT_SYMBOL_GPL(kvm_inject_page_fault);
@@ -8571,6 +8572,7 @@ void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu,
 		fault.error_code = 0;
 		fault.nested_page_fault = false;
 		fault.address = work->arch.token;
+		fault.async_page_fault = true;
 		kvm_inject_page_fault(vcpu, &fault);
 	}
 }
@@ -8593,6 +8595,7 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
 		fault.error_code = 0;
 		fault.nested_page_fault = false;
 		fault.address = work->arch.token;
+		fault.async_page_fault = true;
 		kvm_inject_page_fault(vcpu, &fault);
 	}
 	vcpu->arch.apf.halted = false;
-- 
2.7.4