[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <1573289934-14430-1-git-send-email-linmiaohe@huawei.com>
Date: Sat, 9 Nov 2019 16:58:54 +0800
From: linmiaohe <linmiaohe@...wei.com>
To: <pbonzini@...hat.com>, <rkrcmar@...hat.com>,
<sean.j.christopherson@...el.com>, <vkuznets@...hat.com>,
<wanpengli@...cent.com>, <jmattson@...gle.com>, <joro@...tes.org>,
<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
<hpa@...or.com>
CC: <linmiaohe@...wei.com>, <kvm@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <x86@...nel.org>
Subject: [PATCH] KVM: X86: avoid unused setup_syscalls_segments call when SYSCALL check failed
From: Miaohe Lin <linmiaohe@...wei.com>
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 <linmiaohe@...wei.com>
---
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 698efb8c3897..952d1a4f4d7e 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;
--
2.19.1
Powered by blists - more mailing lists