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Commit 99245b50 authored by Gleb Natapov's avatar Gleb Natapov Committed by Avi Kivity
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KVM: x86 emulator: drop unneeded call to get_segment() 



setup_syscalls_segments() calls get_segment() and than overwrites all
but one of the structure fields and this one should also be overwritten
anyway, so we can drop call to get_segment() and avoid a couple of vmreads
on vmx. Also drop zeroing ss/cs structures since most of the fields are
set anyway. Just set those that were not set explicitly.

Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent f23b070e

arch/x86/kvm/emulate.c

+3 −6
Original line number Diff line number Diff line
@@ -2035,12 +2035,6 @@ static void 
setup_syscalls_segments(struct x86_emulate_ctxt *ctxt,

			struct desc_struct *cs, struct desc_struct *ss)

{

	u16 selector;



	memset(cs, 0, sizeof(struct desc_struct));

	ctxt->ops->get_segment(ctxt, &selector, cs, NULL, VCPU_SREG_CS);

	memset(ss, 0, sizeof(struct desc_struct));



	cs->l = 0;		/* will be adjusted later */

	set_desc_base(cs, 0);	/* flat segment */

	cs->g = 1;		/* 4kb granularity */
@@ -2050,6 +2044,7 @@ setup_syscalls_segments(struct x86_emulate_ctxt *ctxt, 
	cs->dpl = 0;		/* will be adjusted later */

	cs->p = 1;

	cs->d = 1;

	cs->avl = 0;



	set_desc_base(ss, 0);	/* flat segment */

	set_desc_limit(ss, 0xfffff);	/* 4GB limit */
@@ -2059,6 +2054,8 @@ setup_syscalls_segments(struct x86_emulate_ctxt *ctxt, 
	ss->d = 1;		/* 32bit stack segment */

	ss->dpl = 0;

	ss->p = 1;

	ss->l = 0;

	ss->avl = 0;

}



static bool vendor_intel(struct x86_emulate_ctxt *ctxt)