From 5b4ce93a8fe759e2d6b2ee05765cd5a3b4b6a2f1 Mon Sep 17 00:00:00 2001 From: Miaohe Lin Date: Sat, 9 Nov 2019 16:58:54 +0800 Subject: [PATCH] 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: Miaohe Lin Signed-off-by: Paolo Bonzini --- arch/x86/kvm/emulate.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 698efb8..952d1a4 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -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; -- 2.7.4