The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f6ab0107a4942dbf9a5cf0cca3f37e184870a360 Mon Sep 17 00:00:00 2001

From: Sean Christopherson sean.j.christopherson@intel.com Date: Fri, 7 Feb 2020 09:37:42 -0800 Subject: [PATCH] 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: 855feb673640 ("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

diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index 4e1ef0473663..e4c8a4cbf407 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -33,7 +33,7 @@ #define PT_GUEST_ACCESSED_SHIFT PT_ACCESSED_SHIFT #define PT_HAVE_ACCESSED_DIRTY(mmu) true #ifdef CONFIG_X86_64 - #define PT_MAX_FULL_LEVELS 4 + #define PT_MAX_FULL_LEVELS PT64_ROOT_MAX_LEVEL #define CMPXCHG cmpxchg #else #define CMPXCHG cmpxchg64