KVM: MMU: document fast page fault
Document fast page fault to Documentation/virtual/kvm/mmu.txt
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt
index 0aa8e0e..42193f2 100644
--- a/Documentation/virtual/kvm/mmu.txt
+++ b/Documentation/virtual/kvm/mmu.txt
@@ -277,6 +277,9 @@
- walk shadow page table
- cache the information to vcpu->arch.mmio_gva, vcpu->arch.access and
vcpu->arch.mmio_gfn, and call the emulator
+ - If both P bit and R/W bit of error code are set, this could possibly
+ be handled as a "fast page fault" (fixed without taking the MMU lock). See
+ the description in Documentation/virtual/kvm/locking.txt.
- if needed, walk the guest page tables to determine the guest translation
(gva->gpa or ngpa->gpa)
- if permissions are insufficient, reflect the fault back to the guest