From: linmiaohe <linmiaohe@huawei.com>
To: <pbonzini@redhat.com>, <rkrcmar@redhat.com>,
<sean.j.christopherson@intel.com>, <vkuznets@redhat.com>,
<wanpengli@tencent.com>, <jmattson@google.com>, <joro@8bytes.org>,
<tglx@linutronix.de>, <mingo@redhat.com>, <bp@alien8.de>,
<hpa@zytor.com>
Cc: <linmiaohe@huawei.com>, <kvm@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <x86@kernel.org>
Subject: [PATCH] KVM: X86: avoid unused setup_syscalls_segments call when SYSCALL check failed
Date: Sat, 9 Nov 2019 16:58:54 +0800 [thread overview]
Message-ID: <1573289934-14430-1-git-send-email-linmiaohe@huawei.com> (raw)
From: Miaohe Lin <linmiaohe@huawei.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@huawei.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
next reply other threads:[~2019-11-09 8:59 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-09 8:58 linmiaohe [this message]
2019-11-11 14:08 ` [PATCH] KVM: X86: avoid unused setup_syscalls_segments call when SYSCALL check failed Paolo Bonzini
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