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Groups > linux.kernel > #1666390

[PATCH v2 2/4] KVM: async_pf: Add L1 guest async_pf #PF vmexit handler

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

This patch adds the L1 guest async page fault #PF vmexit handler, such
#PF is converted into vmexit from L2 to L1 on #PF which is then handled
by L1 similar to ordinary 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/kvm/vmx.c | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index df825bb..f533cc1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -616,6 +616,7 @@ struct vcpu_vmx {
 	bool emulation_required;
 
 	u32 exit_reason;
+	u32 apf_reason;
 
 	/* Posted interrupt descriptor */
 	struct pi_desc pi_desc;
@@ -5648,14 +5649,31 @@ static int handle_exception(struct kvm_vcpu *vcpu)
 	}
 
 	if (is_page_fault(intr_info)) {
-		/* EPT won't cause page fault directly */
-		BUG_ON(enable_ept);
 		cr2 = vmcs_readl(EXIT_QUALIFICATION);
-		trace_kvm_page_fault(cr2, error_code);
+		switch (vmx->apf_reason) {
+		default:
+			/* EPT won't cause page fault directly */
+			BUG_ON(enable_ept);
+			trace_kvm_page_fault(cr2, error_code);
 
-		if (kvm_event_needs_reinjection(vcpu))
-			kvm_mmu_unprotect_page_virt(vcpu, cr2);
-		return kvm_mmu_page_fault(vcpu, cr2, error_code, NULL, 0);
+			if (kvm_event_needs_reinjection(vcpu))
+				kvm_mmu_unprotect_page_virt(vcpu, cr2);
+			return kvm_mmu_page_fault(vcpu, cr2, error_code, NULL, 0);
+			break;
+		case KVM_PV_REASON_PAGE_NOT_PRESENT:
+			vmx->apf_reason = 0;
+			local_irq_disable();
+			kvm_async_pf_task_wait(cr2);
+			local_irq_enable();
+			break;
+		case KVM_PV_REASON_PAGE_READY:
+			vmx->apf_reason = 0;
+			local_irq_disable();
+			kvm_async_pf_task_wake(cr2);
+			local_irq_enable();
+			break;
+		}
+		return 0;
 	}
 
 	ex_no = intr_info & INTR_INFO_VECTOR_MASK;
@@ -8602,6 +8620,10 @@ static void vmx_complete_atomic_exit(struct vcpu_vmx *vmx)
 	vmx->exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
 	exit_intr_info = vmx->exit_intr_info;
 
+	/* if exit due to PF check for async PF */
+	if (is_page_fault(exit_intr_info))
+		vmx->apf_reason = kvm_read_and_reset_pf_reason();
+
 	/* Handle machine checks before interrupts are enabled */
 	if (is_machine_check(exit_intr_info))
 		kvm_machine_check();
-- 
2.7.4

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[PATCH v2 0/4] KVM: async_pf: Fix async_pf exception injection Wanpeng Li <kernellwp@gmail.com> - 2017-06-15 04:40 +0200
  [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the injected #PF is async_pf Wanpeng Li <kernellwp@gmail.com> - 2017-06-15 04:40 +0200
    Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Radim Krčmář <rkrcmar@redhat.com> - 2017-06-16 15:40 +0200
      Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Wanpeng Li <kernellwp@gmail.com> - 2017-06-16 16:30 +0200
        Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Radim Krčmář <rkrcmar@redhat.com> - 2017-06-16 17:40 +0200
          Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Wanpeng Li <kernellwp@gmail.com> - 2017-06-17 03:50 +0200
          Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Wanpeng Li <kernellwp@gmail.com> - 2017-06-17 08:00 +0200
            Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Radim Krčmář <rkrcmar@redhat.com> - 2017-06-19 17:00 +0200
              Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Wanpeng Li <kernellwp@gmail.com> - 2017-06-19 23:50 +0200
  [PATCH v2 2/4] KVM: async_pf: Add L1 guest async_pf #PF vmexit handler Wanpeng Li <kernellwp@gmail.com> - 2017-06-15 04:40 +0200
  [PATCH v2 4/4] KVM: async_pf: Let host know whether the guest support delivery async_pf as #PF vmexit Wanpeng Li <kernellwp@gmail.com> - 2017-06-15 04:40 +0200

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