From 79d5b4c3cd809c770d4bf9812635647016c56011 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Thu, 7 Jun 2012 17:03:42 +0300 Subject: [PATCH] KVM: x86 emulator: allow loading null SS in long mode Null SS is valid in long mode; allow loading it. Signed-off-by: Avi Kivity --- arch/x86/kvm/emulate.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index db95a55d59369e..fe4340f621371d 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1324,8 +1324,14 @@ static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt, goto load; } - /* NULL selector is not valid for TR, CS and SS */ - if ((seg == VCPU_SREG_CS || seg == VCPU_SREG_SS || seg == VCPU_SREG_TR) + rpl = selector & 3; + cpl = ctxt->ops->cpl(ctxt); + + /* NULL selector is not valid for TR, CS and SS (except for long mode) */ + if ((seg == VCPU_SREG_CS + || (seg == VCPU_SREG_SS + && (ctxt->mode != X86EMUL_MODE_PROT64 || rpl != cpl)) + || seg == VCPU_SREG_TR) && null_selector) goto exception; @@ -1352,9 +1358,7 @@ static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt, goto exception; } - rpl = selector & 3; dpl = seg_desc.dpl; - cpl = ctxt->ops->cpl(ctxt); switch (seg) { case VCPU_SREG_SS: