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authorXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>2013-06-19 17:09:22 +0800
committerGleb Natapov <gleb@redhat.com>2013-06-27 14:20:44 +0300
commit67652ed34390b19ede6f847d23d8c68e2c819b50 (patch)
treee0fbd626e7f812fddbc3ea46fe96cc079fdd7ca8 /Documentation/virtual
parent0cbf8e437b60b8b12d97589509d3e5a581731d36 (diff)
KVM: MMU: document mmio page fault
Document it to Documentation/virtual/kvm/mmu.txt Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation/virtual')
-rw-r--r--Documentation/virtual/kvm/mmu.txt11
1 files changed, 9 insertions, 2 deletions
diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt
index 0db7743c55e1..0aa8e0e34119 100644
--- a/Documentation/virtual/kvm/mmu.txt
+++ b/Documentation/virtual/kvm/mmu.txt
@@ -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:
+ - 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
(gva->gpa or ngpa->gpa)
- if permissions are insufficient, reflect the fault back to the guest
- determine the host page
- - if this is an mmio request, there is no host page; call the emulator
- to emulate the instruction instead
+ - if this is an mmio request, there is no host page; cache the info to
+ vcpu->arch.mmio_gva, vcpu->arch.access and vcpu->arch.mmio_gfn
- walk the shadow page table to find the spte for the translation,
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
- if successful, we can let the guest continue and modify the gpte
- emulate the instruction