From: Wanpeng Li <wanpeng...@hotmail.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 <pbonz...@redhat.com>
Cc: Radim Krčmář <rkrc...@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng...@hotmail.com>
---
 arch/x86/include/asm/kvm_emulate.h |  1 +
 arch/x86/include/asm/kvm_host.h    |  2 ++
 arch/x86/kvm/vmx.c                 | 17 ++++++++++++++---
 arch/x86/kvm/x86.c                 |  8 +++++++-
 4 files changed, 24 insertions(+), 4 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..100ad9a 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 {
@@ -645,6 +646,7 @@ struct kvm_vcpu_arch {
                u64 msr_val;
                u32 id;
                bool send_user_only;
+               unsigned long nested_apf_token;
        } apf;
 
        /* OSVW MSRs (AMD only) */
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f533cc1..e7b9844 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2419,13 +2419,24 @@ static void skip_emulated_instruction(struct kvm_vcpu 
*vcpu)
  * KVM wants to inject page-faults which it got to the guest. This function
  * checks whether in a nested guest, we need to inject them to L1 or L2.
  */
-static int nested_vmx_check_exception(struct kvm_vcpu *vcpu, unsigned nr)
+static int nested_vmx_check_exception(struct kvm_vcpu *vcpu)
 {
        struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
+       unsigned int nr = vcpu->arch.exception.nr;
 
-       if (!(vmcs12->exception_bitmap & (1u << nr)))
+       if (!((vmcs12->exception_bitmap & (1u << nr)) ||
+               (nr == PF_VECTOR && vcpu->arch.exception.async_page_fault)))
                return 0;
 
+       if (vcpu->arch.exception.async_page_fault) {
+               vmcs_write32(VM_EXIT_INTR_ERROR_CODE, 
vcpu->arch.exception.error_code);
+               nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI,
+                       PF_VECTOR | INTR_TYPE_HARD_EXCEPTION |
+                       INTR_INFO_DELIVER_CODE_MASK | INTR_INFO_VALID_MASK,
+                       vcpu->arch.apf.nested_apf_token);
+               return 1;
+       }
+
        nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI,
                          vmcs_read32(VM_EXIT_INTR_INFO),
                          vmcs_readl(EXIT_QUALIFICATION));
@@ -2442,7 +2453,7 @@ static void vmx_queue_exception(struct kvm_vcpu *vcpu)
        u32 intr_info = nr | INTR_INFO_VALID_MASK;
 
        if (!reinject && is_guest_mode(vcpu) &&
-           nested_vmx_check_exception(vcpu, nr))
+           nested_vmx_check_exception(vcpu))
                return;
 
        if (has_error_code) {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1b28a31..5931ce7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -452,7 +452,11 @@ EXPORT_SYMBOL_GPL(kvm_complete_insn_gp);
 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;
+       if (is_guest_mode(vcpu) && vcpu->arch.exception.async_page_fault)
+               vcpu->arch.apf.nested_apf_token = fault->address;
+       else
+               vcpu->arch.cr2 = fault->address;
        kvm_queue_exception_e(vcpu, PF_VECTOR, fault->error_code);
 }
 EXPORT_SYMBOL_GPL(kvm_inject_page_fault);
@@ -8571,6 +8575,7 @@ 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 +8598,7 @@ 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

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