[PATCH v5 2/4] KVM: async_pf: Add L1 guest async_pf #PF vmexit handler

[Wanpeng Li]

From: Wanpeng Li <wanpeng...@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 <pbonz...@redhat.com>
Cc: Radim Krčmář <rkrc...@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng...@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