Commit 67652ed3 authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Gleb Natapov

KVM: MMU: document mmio page fault

Document it to Documentation/virtual/kvm/mmu.txt
Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 0cbf8e43
...@@ -272,14 +272,21 @@ This is the most complicated event. The cause of a page fault can be: ...@@ -272,14 +272,21 @@ This is the most complicated event. The cause of a page fault can be:
Handling a page fault is performed as follows: Handling a page fault is performed as follows:
- if the RSV bit of the error code is set, the page fault is caused by guest
accessing MMIO and cached MMIO information is available.
- 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 needed, walk the guest page tables to determine the guest translation - if needed, walk the guest page tables to determine the guest translation
(gva->gpa or ngpa->gpa) (gva->gpa or ngpa->gpa)
- if permissions are insufficient, reflect the fault back to the guest - if permissions are insufficient, reflect the fault back to the guest
- determine the host page - determine the host page
- if this is an mmio request, there is no host page; call the emulator - if this is an mmio request, there is no host page; cache the info to
to emulate the instruction instead vcpu->arch.mmio_gva, vcpu->arch.access and vcpu->arch.mmio_gfn
- walk the shadow page table to find the spte for the translation, - walk the shadow page table to find the spte for the translation,
instantiating missing intermediate page tables as necessary instantiating missing intermediate page tables as necessary
- If this is an mmio request, cache the mmio info to the spte and set some
reserved bit on the spte (see callers of kvm_mmu_set_mmio_spte_mask)
- try to unsynchronize the page - try to unsynchronize the page
- if successful, we can let the guest continue and modify the gpte - if successful, we can let the guest continue and modify the gpte
- emulate the instruction - emulate the instruction
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment