diff options
Diffstat (limited to 'KVM-x86-Decoding-guest-instructions-which-cross-page.patch')
| -rw-r--r-- | KVM-x86-Decoding-guest-instructions-which-cross-page.patch | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/KVM-x86-Decoding-guest-instructions-which-cross-page.patch b/KVM-x86-Decoding-guest-instructions-which-cross-page.patch new file mode 100644 index 000000000..86ed83f8f --- /dev/null +++ b/KVM-x86-Decoding-guest-instructions-which-cross-page.patch @@ -0,0 +1,38 @@ +From: Nadav Amit <namit@cs.technion.ac.il> +Date: Fri, 24 Oct 2014 17:07:20 +0200 +Subject: [PATCH] KVM: x86: Decoding guest instructions which cross page + boundary may fail + +Once an instruction crosses a page boundary, the size read from the second page +disregards the common case that part of the operand resides on the first page. +As a result, fetch of long insturctions may fail, and thereby cause the +decoding to fail as well. + +Cc: stable@vger.kernel.org +Fixes: 5cfc7e0f5e5e1adf998df94f8e36edaf5d30d38e +Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> +Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> +--- + arch/x86/kvm/emulate.c | 6 ++++-- + 1 file changed, 4 insertions(+), 2 deletions(-) + +diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c +index c0deaff8d9f0..02c8ea804aaf 100644 +--- a/arch/x86/kvm/emulate.c ++++ b/arch/x86/kvm/emulate.c +@@ -778,8 +778,10 @@ static int __do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt, int op_size) + static __always_inline int do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt, + unsigned size) + { +- if (unlikely(ctxt->fetch.end - ctxt->fetch.ptr < size)) +- return __do_insn_fetch_bytes(ctxt, size); ++ unsigned done_size = ctxt->fetch.end - ctxt->fetch.ptr; ++ ++ if (unlikely(done_size < size)) ++ return __do_insn_fetch_bytes(ctxt, size - done_size); + else + return X86EMUL_CONTINUE; + } +-- +1.9.3 + |