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KVM: x86/mmu: Fix struct guest_walker arrays for 5-level paging 

Define PT_MAX_FULL_LEVELS as PT64_ROOT_MAX_LEVEL, i.e. 5, to fix shadow
paging for 5-level guest page tables.  PT_MAX_FULL_LEVELS is used to
size the arrays that track guest pages table information, i.e. using a
"max levels" of 4 causes KVM to access garbage beyond the end of an
array when querying state for level 5 entries.  E.g. FNAME(gpte_changed)
will read garbage and most likely return %true for a level 5 entry,
soft-hanging the guest because FNAME(fetch) will restart the guest
instead of creating SPTEs because it thinks the guest PTE has changed.

Note, KVM doesn't yet support 5-level nested EPT, so PT_MAX_FULL_LEVELS
gets to stay "4" for the PTTYPE_EPT case.

Fixes: 855feb6736 ("KVM: MMU: Add 5 level EPT & Shadow page table support.")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2020-02-07 09:37:42 -08:00 committed by Paolo Bonzini
parent 148d735eb5
commit f6ab0107a4
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kvm/mmu/paging_tmpl.h
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@ -33,7 +33,7 @@
#define PT_GUEST_ACCESSED_SHIFT PT_ACCESSED_SHIFT #define PT_GUEST_ACCESSED_SHIFT PT_ACCESSED_SHIFT
#define PT_HAVE_ACCESSED_DIRTY(mmu) true #define PT_HAVE_ACCESSED_DIRTY(mmu) true
#ifdef CONFIG_X86_64 #ifdef CONFIG_X86_64
#define PT_MAX_FULL_LEVELS 4 #define PT_MAX_FULL_LEVELS PT64_ROOT_MAX_LEVEL
#define CMPXCHG cmpxchg #define CMPXCHG cmpxchg
#else #else
#define CMPXCHG cmpxchg64 #define CMPXCHG cmpxchg64