2014-10-03 01:10+0300, Nadav Amit: > 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. > > Signed-off-by: Nadav Amit <namit@xxxxxxxxxxxxxxxxx> > --- Good catch, was it thanks to an exhaustive test-suite? Reviewed-by: Radim Krčmář <rkrcmar@xxxxxxxxxx> > 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 694dfa7..b2e8aba 100644 > --- a/arch/x86/kvm/emulate.c > +++ b/arch/x86/kvm/emulate.c > @@ -751,8 +751,10 @@ 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; > } > -- > 1.9.1 > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html