Re: [Xen-devel] [PATCH v3 1/3] x86/HVM: drop hvm_fetch_from_guest_linear()

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: 06 September 2018 14:03
> To: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
> Cc: Olaf Hering <olaf@xxxxxxxxx>; Andrew Cooper
> <Andrew.Cooper3@xxxxxxxxxx>; Paul Durrant <Paul.Durrant@xxxxxxxxxx>;
> Tim (Xen.org) <tim@xxxxxxx>
> Subject: [PATCH v3 1/3] x86/HVM: drop hvm_fetch_from_guest_linear()
> 
> It can easily be expressed through hvm_copy_from_guest_linear(), and in
> two cases this even simplifies callers.
> 
> Suggested-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Tested-by: Olaf Hering <olaf@xxxxxxxxx>

Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

> ---
> v2: Make sure this compiles standalone. Slightly adjust change in
>     hvm_ud_intercept().
> 
> --- a/xen/arch/x86/hvm/emulate.c
> +++ b/xen/arch/x86/hvm/emulate.c
> @@ -1060,6 +1060,8 @@ static int __hvmemul_read(
>          pfec |= PFEC_implicit;
>      else if ( hvmemul_ctxt->seg_reg[x86_seg_ss].dpl == 3 )
>          pfec |= PFEC_user_mode;
> +    if ( access_type == hvm_access_insn_fetch )
> +        pfec |= PFEC_insn_fetch;
> 
>      rc = hvmemul_virtual_to_linear(
>          seg, offset, bytes, &reps, access_type, hvmemul_ctxt, &addr);
> @@ -1071,9 +1073,7 @@ static int __hvmemul_read(
>           (vio->mmio_gla == (addr & PAGE_MASK)) )
>          return hvmemul_linear_mmio_read(addr, bytes, p_data, pfec,
> hvmemul_ctxt, 1);
> 
> -    rc = ((access_type == hvm_access_insn_fetch) ?
> -          hvm_fetch_from_guest_linear(p_data, addr, bytes, pfec, &pfinfo) :
> -          hvm_copy_from_guest_linear(p_data, addr, bytes, pfec, &pfinfo));
> +    rc = hvm_copy_from_guest_linear(p_data, addr, bytes, pfec, &pfinfo);
> 
>      switch ( rc )
>      {
> @@ -2512,9 +2512,10 @@ void hvm_emulate_init_per_insn(
>                                          hvm_access_insn_fetch,
>                                          &hvmemul_ctxt->seg_reg[x86_seg_cs],
>                                          &addr) &&
> -             hvm_fetch_from_guest_linear(hvmemul_ctxt->insn_buf, addr,
> -                                         sizeof(hvmemul_ctxt->insn_buf),
> -                                         pfec, NULL) == HVMTRANS_okay) ?
> +             hvm_copy_from_guest_linear(hvmemul_ctxt->insn_buf, addr,
> +                                        sizeof(hvmemul_ctxt->insn_buf),
> +                                        pfec | PFEC_insn_fetch,
> +                                        NULL) == HVMTRANS_okay) ?
>              sizeof(hvmemul_ctxt->insn_buf) : 0;
>      }
>      else
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -3286,15 +3286,6 @@ enum hvm_translation_result hvm_copy_fro
>                        PFEC_page_present | pfec, pfinfo);
>  }
> 
> -enum hvm_translation_result hvm_fetch_from_guest_linear(
> -    void *buf, unsigned long addr, int size, uint32_t pfec,
> -    pagefault_info_t *pfinfo)
> -{
> -    return __hvm_copy(buf, addr, size, current,
> -                      HVMCOPY_from_guest | HVMCOPY_linear,
> -                      PFEC_page_present | PFEC_insn_fetch | pfec, pfinfo);
> -}
> -
>  unsigned long copy_to_user_hvm(void *to, const void *from, unsigned int
> len)
>  {
>      int rc;
> @@ -3740,16 +3731,16 @@ void hvm_ud_intercept(struct cpu_user_re
>      if ( opt_hvm_fep )
>      {
>          const struct segment_register *cs = &ctxt.seg_reg[x86_seg_cs];
> -        uint32_t walk = (ctxt.seg_reg[x86_seg_ss].dpl == 3)
> -            ? PFEC_user_mode : 0;
> +        uint32_t walk = ((ctxt.seg_reg[x86_seg_ss].dpl == 3)
> +                         ? PFEC_user_mode : 0) | PFEC_insn_fetch;
>          unsigned long addr;
>          char sig[5]; /* ud2; .ascii "xen" */
> 
>          if ( hvm_virtual_to_linear_addr(x86_seg_cs, cs, regs->rip,
>                                          sizeof(sig), hvm_access_insn_fetch,
>                                          cs, &addr) &&
> -             (hvm_fetch_from_guest_linear(sig, addr, sizeof(sig),
> -                                          walk, NULL) == HVMTRANS_okay) &&
> +             (hvm_copy_from_guest_linear(sig, addr, sizeof(sig),
> +                                         walk, NULL) == HVMTRANS_okay) &&
>               (memcmp(sig, "\xf\xbxen", sizeof(sig)) == 0) )
>          {
>              regs->rip += sizeof(sig);
> --- a/xen/arch/x86/mm/shadow/common.c
> +++ b/xen/arch/x86/mm/shadow/common.c
> @@ -164,8 +164,9 @@ const struct x86_emulate_ops *shadow_ini
>          (!hvm_translate_virtual_addr(
>              x86_seg_cs, regs->rip, sizeof(sh_ctxt->insn_buf),
>              hvm_access_insn_fetch, sh_ctxt, &addr) &&
> -         !hvm_fetch_from_guest_linear(
> -             sh_ctxt->insn_buf, addr, sizeof(sh_ctxt->insn_buf), 0, NULL))
> +         !hvm_copy_from_guest_linear(
> +             sh_ctxt->insn_buf, addr, sizeof(sh_ctxt->insn_buf),
> +             PFEC_insn_fetch, NULL))
>          ? sizeof(sh_ctxt->insn_buf) : 0;
> 
>      return &hvm_shadow_emulator_ops;
> @@ -198,8 +199,9 @@ void shadow_continue_emulation(struct sh
>              (!hvm_translate_virtual_addr(
>                  x86_seg_cs, regs->rip, sizeof(sh_ctxt->insn_buf),
>                  hvm_access_insn_fetch, sh_ctxt, &addr) &&
> -             !hvm_fetch_from_guest_linear(
> -                 sh_ctxt->insn_buf, addr, sizeof(sh_ctxt->insn_buf), 0, 
> NULL))
> +             !hvm_copy_from_guest_linear(
> +                 sh_ctxt->insn_buf, addr, sizeof(sh_ctxt->insn_buf),
> +                 PFEC_insn_fetch, NULL))
>              ? sizeof(sh_ctxt->insn_buf) : 0;
>          sh_ctxt->insn_buf_eip = regs->rip;
>      }
> --- a/xen/arch/x86/mm/shadow/hvm.c
> +++ b/xen/arch/x86/mm/shadow/hvm.c
> @@ -122,10 +122,10 @@ hvm_read(enum x86_segment seg,
>      if ( rc || !bytes )
>          return rc;
> 
> -    if ( access_type == hvm_access_insn_fetch )
> -        rc = hvm_fetch_from_guest_linear(p_data, addr, bytes, 0, &pfinfo);
> -    else
> -        rc = hvm_copy_from_guest_linear(p_data, addr, bytes, 0, &pfinfo);
> +    rc = hvm_copy_from_guest_linear(p_data, addr, bytes,
> +                                    (access_type == hvm_access_insn_fetch
> +                                     ? PFEC_insn_fetch : 0),
> +                                    &pfinfo);
> 
>      switch ( rc )
>      {
> --- a/xen/include/asm-x86/hvm/support.h
> +++ b/xen/include/asm-x86/hvm/support.h
> @@ -100,9 +100,6 @@ enum hvm_translation_result hvm_copy_to_
>  enum hvm_translation_result hvm_copy_from_guest_linear(
>      void *buf, unsigned long addr, int size, uint32_t pfec,
>      pagefault_info_t *pfinfo);
> -enum hvm_translation_result hvm_fetch_from_guest_linear(
> -    void *buf, unsigned long addr, int size, uint32_t pfec,
> -    pagefault_info_t *pfinfo);
> 
>  /*
>   * Get a reference on the page under an HVM physical or linear address.  If
> 
> 


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