Il 16/06/2014 19:38, Bandan Das ha scritto:
Nadav Amit <namit@xxxxxxxxxxxxxxxxx> writes:The emulator does not emulate the xadd instruction correctly if the two operands are the same. In this (unlikely) situation the result should be the sum of X and X (2X) when it is currently X. The solution is to first perform writeback to the source, before writing to the destination. The only instruction which should be affected is xadd, as the other instructions that perform writeback to the source use the extended accumlator (e.g., RAX:RDX). Signed-off-by: Nadav Amit <namit@xxxxxxxxxxxxxxxxx> --- arch/x86/kvm/emulate.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index f0b0a10..3c8d867 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -4711,17 +4711,17 @@ special_insn: goto done; writeback: - if (!(ctxt->d & NoWrite)) { - rc = writeback(ctxt, &ctxt->dst); - if (rc != X86EMUL_CONTINUE) - goto done; - } if (ctxt->d & SrcWrite) { BUG_ON(ctxt->src.type == OP_MEM || ctxt->src.type == OP_MEM_STR);While we are here, I think we should replace this BUG_ON with a warning and return X86EMUL_UNHANDLEABLE if the condition is true.
Sure, please post a patch and I'll apply it right away. Paolo -- 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
