Commit 5b4ce93a authored by Miaohe Lin's avatar Miaohe Lin Committed by Paolo Bonzini
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KVM: X86: avoid unused setup_syscalls_segments call when SYSCALL check failed 



When SYSCALL/SYSENTER ability check failed, cs and ss is inited but
remain not used. Delay initializing cs and ss until SYSCALL/SYSENTER
ability check passed.

Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent b139b5a2

arch/x86/kvm/emulate.c

+2 −4
Original line number Diff line number Diff line
@@ -2770,11 +2770,10 @@ static int em_syscall(struct x86_emulate_ctxt *ctxt) 
		return emulate_ud(ctxt);



	ops->get_msr(ctxt, MSR_EFER, &efer);

	setup_syscalls_segments(ctxt, &cs, &ss);



	if (!(efer & EFER_SCE))

		return emulate_ud(ctxt);



	setup_syscalls_segments(ctxt, &cs, &ss);

	ops->get_msr(ctxt, MSR_STAR, &msr_data);

	msr_data >>= 32;

	cs_sel = (u16)(msr_data & 0xfffc);
@@ -2838,12 +2837,11 @@ static int em_sysenter(struct x86_emulate_ctxt *ctxt) 
	if (ctxt->mode == X86EMUL_MODE_PROT64)

		return X86EMUL_UNHANDLEABLE;



	setup_syscalls_segments(ctxt, &cs, &ss);



	ops->get_msr(ctxt, MSR_IA32_SYSENTER_CS, &msr_data);

	if ((msr_data & 0xfffc) == 0x0)

		return emulate_gp(ctxt, 0);



	setup_syscalls_segments(ctxt, &cs, &ss);

	ctxt->eflags &= ~(X86_EFLAGS_VM | X86_EFLAGS_IF);

	cs_sel = (u16)msr_data & ~SEGMENT_RPL_MASK;

	ss_sel = cs_sel + 8;