* [PATCH] KVM: X86: avoid unused setup_syscalls_segments call when SYSCALL check failed
@ 2019-11-09 8:58 linmiaohe
2019-11-11 14:08 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: linmiaohe @ 2019-11-09 8:58 UTC (permalink / raw)
To: pbonzini, rkrcmar, sean.j.christopherson, vkuznets, wanpengli,
jmattson, joro, tglx, mingo, bp, hpa
Cc: linmiaohe, kvm, linux-kernel, x86
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] KVM: X86: avoid unused setup_syscalls_segments call when SYSCALL check failed
2019-11-09 8:58 [PATCH] KVM: X86: avoid unused setup_syscalls_segments call when SYSCALL check failed linmiaohe
@ 2019-11-11 14:08 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2019-11-11 14:08 UTC (permalink / raw)
To: linmiaohe, rkrcmar, sean.j.christopherson, vkuznets, wanpengli,
jmattson, joro, tglx, mingo, bp, hpa
Cc: kvm, linux-kernel, x86
On 09/11/19 09:58, linmiaohe wrote:
> 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;
>
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 2+ messages in thread
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