From e2cefa746e7e2a1104931d411b6f5de159d98ec6 Mon Sep 17 00:00:00 2001 From: Nadav Amit Date: Thu, 25 Dec 2014 02:52:22 +0200 Subject: [PATCH] KVM: x86: Do not set access bit on accessed segments When segment is loaded, the segment access bit is set unconditionally. In fact, it should be set conditionally, based on whether the segment had the accessed bit set before. In addition, it can improve performance. Signed-off-by: Nadav Amit Signed-off-by: Paolo Bonzini --- arch/x86/kvm/emulate.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index cc24b74b7454..e36e1fc5bf85 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1618,10 +1618,13 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt, if (seg_desc.s) { /* mark segment as accessed */ - seg_desc.type |= 1; - ret = write_segment_descriptor(ctxt, selector, &seg_desc); - if (ret != X86EMUL_CONTINUE) - return ret; + if (!(seg_desc.type & 1)) { + seg_desc.type |= 1; + ret = write_segment_descriptor(ctxt, selector, + &seg_desc); + if (ret != X86EMUL_CONTINUE) + return ret; + } } else if (ctxt->mode == X86EMUL_MODE_PROT64) { ret = ctxt->ops->read_std(ctxt, desc_addr+8, &base3, sizeof(base3), &ctxt->exception); -- 2.20.1