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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-07-24 09:07:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-07-24 09:07:03 -0700 |
| commit | 5fabc487c96819dd12ddb9414835d170fd9cd6d5 (patch) | |
| tree | 01532d492e5074b0d3add29bf92ebf9a9d161e9e /Documentation/virtual/kvm/mmu.txt | |
| parent | c61264f98c1a974ee6f545f61a4ab33b141d6bda (diff) | |
| parent | 3f68b0318bbbd61bf08478ab99a149f0d9e5156e (diff) | |
Merge branch 'kvm-updates/3.1' of git://git.kernel.org/pub/scm/virt/kvm/kvm
* 'kvm-updates/3.1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (143 commits)
KVM: IOMMU: Disable device assignment without interrupt remapping
KVM: MMU: trace mmio page fault
KVM: MMU: mmio page fault support
KVM: MMU: reorganize struct kvm_shadow_walk_iterator
KVM: MMU: lockless walking shadow page table
KVM: MMU: do not need atomicly to set/clear spte
KVM: MMU: introduce the rules to modify shadow page table
KVM: MMU: abstract some functions to handle fault pfn
KVM: MMU: filter out the mmio pfn from the fault pfn
KVM: MMU: remove bypass_guest_pf
KVM: MMU: split kvm_mmu_free_page
KVM: MMU: count used shadow pages on prepareing path
KVM: MMU: rename 'pt_write' to 'emulate'
KVM: MMU: cleanup for FNAME(fetch)
KVM: MMU: optimize to handle dirty bit
KVM: MMU: cache mmio info on page fault path
KVM: x86: introduce vcpu_mmio_gva_to_gpa to cleanup the code
KVM: MMU: do not update slot bitmap if spte is nonpresent
KVM: MMU: fix walking shadow page table
KVM guest: KVM Steal time registration
...
Diffstat (limited to 'Documentation/virtual/kvm/mmu.txt')
| -rw-r--r-- | Documentation/virtual/kvm/mmu.txt | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt index f46aa58389ca..5dc972c09b55 100644 --- a/Documentation/virtual/kvm/mmu.txt +++ b/Documentation/virtual/kvm/mmu.txt @@ -165,6 +165,10 @@ Shadow pages contain the following information: Contains the value of efer.nxe for which the page is valid. role.cr0_wp: Contains the value of cr0.wp for which the page is valid. + role.smep_andnot_wp: + Contains the value of cr4.smep && !cr0.wp for which the page is valid + (pages for which this is true are different from other pages; see the + treatment of cr0.wp=0 below). gfn: Either the guest page table containing the translations shadowed by this page, or the base page frame for linear translations. See role.direct. @@ -317,6 +321,20 @@ on fault type: (user write faults generate a #PF) +In the first case there is an additional complication if CR4.SMEP is +enabled: since we've turned the page into a kernel page, the kernel may now +execute it. We handle this by also setting spte.nx. If we get a user +fetch or read fault, we'll change spte.u=1 and spte.nx=gpte.nx back. + +To prevent an spte that was converted into a kernel page with cr0.wp=0 +from being written by the kernel after cr0.wp has changed to 1, we make +the value of cr0.wp part of the page role. This means that an spte created +with one value of cr0.wp cannot be used when cr0.wp has a different value - +it will simply be missed by the shadow page lookup code. A similar issue +exists when an spte created with cr0.wp=0 and cr4.smep=0 is used after +changing cr4.smep to 1. To avoid this, the value of !cr0.wp && cr4.smep +is also made a part of the page role. + Large pages =========== |