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

Wanpeng Li
2017-06-13T06:08:13Z

From: Wanpeng Li <wanpeng.li@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 <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.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