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

Wanpeng Li
2017-06-13T06:08:12Z

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