path: root/virt
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authorXiao Guangrong <>2011-07-12 03:33:44 +0800
committerAvi Kivity <>2011-07-24 11:50:40 +0300
commitce88decffd17bf9f373cc233c961ad2054965667 (patch)
tree65202d01a10c790eacb4b63bacc5fccfbe5bb050 /virt
parentdd3bfd59dbc69fd970394ab354cfca5f959d5755 (diff)
KVM: MMU: mmio page fault support
The idea is from Avi: | We could cache the result of a miss in an spte by using a reserved bit, and | checking the page fault error code (or seeing if we get an ept violation or | ept misconfiguration), so if we get repeated mmio on a page, we don't need to | search the slot list/tree. | ( When the page fault is caused by mmio, we cache the info in the shadow page table, and also set the reserved bits in the shadow page table, so if the mmio is caused again, we can quickly identify it and emulate it directly Searching mmio gfn in memslots is heavy since we need to walk all memeslots, it can be reduced by this feature, and also avoid walking guest page table for soft mmu. [jan: fix operator precedence issue] Signed-off-by: Xiao Guangrong <> Signed-off-by: Jan Kiszka <> Signed-off-by: Avi Kivity <>
Diffstat (limited to 'virt')
1 files changed, 7 insertions, 0 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 56f3c704fd74..aefdda390f5e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -831,6 +831,13 @@ skip_lpage:
kvm_arch_commit_memory_region(kvm, mem, old, user_alloc);
+ /*
+ * If the new memory slot is created, we need to clear all
+ * mmio sptes.
+ */
+ if (npages && old.base_gfn != mem->guest_phys_addr >> PAGE_SHIFT)
+ kvm_arch_flush_shadow(kvm);
kvm_free_physmem_slot(&old, &new);