linux-kernel - Re: [PATCH 3/5] KVM: x86: emulate sldt and str

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Date:   Wed, 15 Nov 2017 08:41:21 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kvm <kvm@...r.kernel.org>, Radim Krcmar <rkrcmar@...hat.com>
Subject: Re: [PATCH 3/5] KVM: x86: emulate sldt and str

2017-11-13 22:40 GMT+08:00 Paolo Bonzini <pbonzini@...hat.com>:
> These are needed to handle the descriptor table vmexits when emulating
> UMIP.
>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>

Reviewed-by: Wanpeng Li <wanpeng.li@...mail.com>

> ---
>  arch/x86/kvm/emulate.c | 32 ++++++++++++++++++++++++++------
>  1 file changed, 26 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index d27339332ac8..da2c5590240a 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -3638,17 +3638,27 @@ static int em_rdmsr(struct x86_emulate_ctxt *ctxt)
>         return X86EMUL_CONTINUE;
>  }
>
> -static int em_mov_rm_sreg(struct x86_emulate_ctxt *ctxt)
> +static int em_store_sreg(struct x86_emulate_ctxt *ctxt, int segment)
>  {
> -       if (ctxt->modrm_reg > VCPU_SREG_GS)
> -               return emulate_ud(ctxt);
> +       if (segment > VCPU_SREG_GS &&
> +           (ctxt->ops->get_cr(ctxt, 4) & X86_CR4_UMIP) &&
> +           ctxt->ops->cpl(ctxt) > 0)
> +               return emulate_gp(ctxt, 0);
>
> -       ctxt->dst.val = get_segment_selector(ctxt, ctxt->modrm_reg);
> +       ctxt->dst.val = get_segment_selector(ctxt, segment);
>         if (ctxt->dst.bytes == 4 && ctxt->dst.type == OP_MEM)
>                 ctxt->dst.bytes = 2;
>         return X86EMUL_CONTINUE;
>  }
>
> +static int em_mov_rm_sreg(struct x86_emulate_ctxt *ctxt)
> +{
> +       if (ctxt->modrm_reg > VCPU_SREG_GS)
> +               return emulate_ud(ctxt);
> +
> +       return em_store_sreg(ctxt, ctxt->modrm_reg);
> +}
> +
>  static int em_mov_sreg_rm(struct x86_emulate_ctxt *ctxt)
>  {
>         u16 sel = ctxt->src.val;
> @@ -3664,6 +3674,11 @@ static int em_mov_sreg_rm(struct x86_emulate_ctxt *ctxt)
>         return load_segment_descriptor(ctxt, sel, ctxt->modrm_reg);
>  }
>
> +static int em_sldt(struct x86_emulate_ctxt *ctxt)
> +{
> +       return em_store_sreg(ctxt, VCPU_SREG_LDTR);
> +}
> +
>  static int em_lldt(struct x86_emulate_ctxt *ctxt)
>  {
>         u16 sel = ctxt->src.val;
> @@ -3673,6 +3688,11 @@ static int em_lldt(struct x86_emulate_ctxt *ctxt)
>         return load_segment_descriptor(ctxt, sel, VCPU_SREG_LDTR);
>  }
>
> +static int em_str(struct x86_emulate_ctxt *ctxt)
> +{
> +       return em_store_sreg(ctxt, VCPU_SREG_TR);
> +}
> +
>  static int em_ltr(struct x86_emulate_ctxt *ctxt)
>  {
>         u16 sel = ctxt->src.val;
> @@ -4365,8 +4385,8 @@ static int check_perm_out(struct x86_emulate_ctxt *ctxt)
>  };
>
>  static const struct opcode group6[] = {
> -       DI(Prot | DstMem,       sldt),
> -       DI(Prot | DstMem,       str),
> +       II(Prot | DstMem,          em_sldt, sldt),
> +       II(Prot | DstMem,          em_str, str),
>         II(Prot | Priv | SrcMem16, em_lldt, lldt),
>         II(Prot | Priv | SrcMem16, em_ltr, ltr),
>         N, N, N, N,
> --
> 1.8.3.1
>
>