[01/15] x86/hvm: Rename hvm_emulate_init() and hvm_emulate_prepare() for clarity
diff mbox

Message ID 1479915538-15282-2-git-send-email-andrew.cooper3@citrix.com
State New, archived
Headers show

Commit Message

Andrew Cooper Nov. 23, 2016, 3:38 p.m. UTC
* Move hvm_emulate_init() to immediately hvm_emulate_prepare(), as they are
   very closely related.
 * Rename hvm_emulate_prepare() to hvm_emulate_init_once() and
   hvm_emulate_init() to hvm_emulate_init_per_insn() to make it clearer how to
   and when to use them.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Paul Durrant <paul.durrant@citrix.com>
CC: Jun Nakajima <jun.nakajima@intel.com>
CC: Kevin Tian <kevin.tian@intel.com>
CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
CC: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
CC: Wei Liu <wei.liu2@citrix.com>

As hvm_emulate_prepare() was new in 4.8, it would be a good idea to take this
patch to avoid future confusion on the stable-4.8 branch
---
 xen/arch/x86/hvm/emulate.c        | 111 +++++++++++++++++++-------------------
 xen/arch/x86/hvm/hvm.c            |   2 +-
 xen/arch/x86/hvm/io.c             |   2 +-
 xen/arch/x86/hvm/ioreq.c          |   2 +-
 xen/arch/x86/hvm/svm/emulate.c    |   4 +-
 xen/arch/x86/hvm/vmx/realmode.c   |   2 +-
 xen/include/asm-x86/hvm/emulate.h |   6 ++-
 7 files changed, 66 insertions(+), 63 deletions(-)

Comments

Paul Durrant Nov. 23, 2016, 3:49 p.m. UTC | #1
> -----Original Message-----
> From: Andrew Cooper [mailto:andrew.cooper3@citrix.com]
> Sent: 23 November 2016 15:39
> To: Xen-devel <xen-devel@lists.xen.org>
> Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>; Jan Beulich
> <JBeulich@suse.com>; Paul Durrant <Paul.Durrant@citrix.com>; Jun
> Nakajima <jun.nakajima@intel.com>; Kevin Tian <kevin.tian@intel.com>;
> Boris Ostrovsky <boris.ostrovsky@oracle.com>; Suravee Suthikulpanit
> <suravee.suthikulpanit@amd.com>; Wei Liu <wei.liu2@citrix.com>
> Subject: [PATCH 01/15] x86/hvm: Rename hvm_emulate_init() and
> hvm_emulate_prepare() for clarity
> 
>  * Move hvm_emulate_init() to immediately hvm_emulate_prepare(), as
> they are
>    very closely related.
>  * Rename hvm_emulate_prepare() to hvm_emulate_init_once() and
>    hvm_emulate_init() to hvm_emulate_init_per_insn() to make it clearer
> how to
>    and when to use them.
> 
> No functional change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

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

> ---
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Paul Durrant <paul.durrant@citrix.com>
> CC: Jun Nakajima <jun.nakajima@intel.com>
> CC: Kevin Tian <kevin.tian@intel.com>
> CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> CC: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> CC: Wei Liu <wei.liu2@citrix.com>
> 
> As hvm_emulate_prepare() was new in 4.8, it would be a good idea to take
> this
> patch to avoid future confusion on the stable-4.8 branch
> ---
>  xen/arch/x86/hvm/emulate.c        | 111 +++++++++++++++++++---------------
> ----
>  xen/arch/x86/hvm/hvm.c            |   2 +-
>  xen/arch/x86/hvm/io.c             |   2 +-
>  xen/arch/x86/hvm/ioreq.c          |   2 +-
>  xen/arch/x86/hvm/svm/emulate.c    |   4 +-
>  xen/arch/x86/hvm/vmx/realmode.c   |   2 +-
>  xen/include/asm-x86/hvm/emulate.h |   6 ++-
>  7 files changed, 66 insertions(+), 63 deletions(-)
> 
> diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
> index e9b8f8c..3ab0e8e 100644
> --- a/xen/arch/x86/hvm/emulate.c
> +++ b/xen/arch/x86/hvm/emulate.c
> @@ -1755,57 +1755,6 @@ static const struct x86_emulate_ops
> hvm_emulate_ops_no_write = {
>      .vmfunc        = hvmemul_vmfunc,
>  };
> 
> -void hvm_emulate_init(
> -    struct hvm_emulate_ctxt *hvmemul_ctxt,
> -    const unsigned char *insn_buf,
> -    unsigned int insn_bytes)
> -{
> -    struct vcpu *curr = current;
> -    unsigned int pfec = PFEC_page_present;
> -    unsigned long addr;
> -
> -    if ( hvm_long_mode_enabled(curr) &&
> -         hvmemul_ctxt->seg_reg[x86_seg_cs].attr.fields.l )
> -    {
> -        hvmemul_ctxt->ctxt.addr_size = hvmemul_ctxt->ctxt.sp_size = 64;
> -    }
> -    else
> -    {
> -        hvmemul_ctxt->ctxt.addr_size =
> -            hvmemul_ctxt->seg_reg[x86_seg_cs].attr.fields.db ? 32 : 16;
> -        hvmemul_ctxt->ctxt.sp_size =
> -            hvmemul_ctxt->seg_reg[x86_seg_ss].attr.fields.db ? 32 : 16;
> -    }
> -
> -    if ( hvmemul_ctxt->seg_reg[x86_seg_ss].attr.fields.dpl == 3 )
> -        pfec |= PFEC_user_mode;
> -
> -    hvmemul_ctxt->insn_buf_eip = hvmemul_ctxt->ctxt.regs->eip;
> -    if ( !insn_bytes )
> -    {
> -        hvmemul_ctxt->insn_buf_bytes =
> -            hvm_get_insn_bytes(curr, hvmemul_ctxt->insn_buf) ?:
> -            (hvm_virtual_to_linear_addr(x86_seg_cs,
> -                                        &hvmemul_ctxt->seg_reg[x86_seg_cs],
> -                                        hvmemul_ctxt->insn_buf_eip,
> -                                        sizeof(hvmemul_ctxt->insn_buf),
> -                                        hvm_access_insn_fetch,
> -                                        hvmemul_ctxt->ctxt.addr_size,
> -                                        &addr) &&
> -             hvm_fetch_from_guest_virt_nofault(hvmemul_ctxt->insn_buf,
> addr,
> -                                               sizeof(hvmemul_ctxt->insn_buf),
> -                                               pfec) == HVMCOPY_okay) ?
> -            sizeof(hvmemul_ctxt->insn_buf) : 0;
> -    }
> -    else
> -    {
> -        hvmemul_ctxt->insn_buf_bytes = insn_bytes;
> -        memcpy(hvmemul_ctxt->insn_buf, insn_buf, insn_bytes);
> -    }
> -
> -    hvmemul_ctxt->exn_pending = 0;
> -}
> -
>  static int _hvm_emulate_one(struct hvm_emulate_ctxt *hvmemul_ctxt,
>      const struct x86_emulate_ops *ops)
>  {
> @@ -1815,7 +1764,8 @@ static int _hvm_emulate_one(struct
> hvm_emulate_ctxt *hvmemul_ctxt,
>      struct hvm_vcpu_io *vio = &curr->arch.hvm_vcpu.hvm_io;
>      int rc;
> 
> -    hvm_emulate_init(hvmemul_ctxt, vio->mmio_insn, vio-
> >mmio_insn_bytes);
> +    hvm_emulate_init_per_insn(hvmemul_ctxt, vio->mmio_insn,
> +                              vio->mmio_insn_bytes);
> 
>      vio->mmio_retry = 0;
> 
> @@ -1915,7 +1865,7 @@ int hvm_emulate_one_mmio(unsigned long mfn,
> unsigned long gla)
>      else
>          ops = &hvm_ro_emulate_ops_mmio;
> 
> -    hvm_emulate_prepare(&ctxt, guest_cpu_user_regs());
> +    hvm_emulate_init_once(&ctxt, guest_cpu_user_regs());
>      ctxt.ctxt.data = &mmio_ro_ctxt;
>      rc = _hvm_emulate_one(&ctxt, ops);
>      switch ( rc )
> @@ -1940,7 +1890,7 @@ void hvm_emulate_one_vm_event(enum
> emul_kind kind, unsigned int trapnr,
>      struct hvm_emulate_ctxt ctx = {{ 0 }};
>      int rc;
> 
> -    hvm_emulate_prepare(&ctx, guest_cpu_user_regs());
> +    hvm_emulate_init_once(&ctx, guest_cpu_user_regs());
> 
>      switch ( kind )
>      {
> @@ -1992,7 +1942,7 @@ void hvm_emulate_one_vm_event(enum
> emul_kind kind, unsigned int trapnr,
>      hvm_emulate_writeback(&ctx);
>  }
> 
> -void hvm_emulate_prepare(
> +void hvm_emulate_init_once(
>      struct hvm_emulate_ctxt *hvmemul_ctxt,
>      struct cpu_user_regs *regs)
>  {
> @@ -2006,6 +1956,57 @@ void hvm_emulate_prepare(
>      hvmemul_get_seg_reg(x86_seg_ss, hvmemul_ctxt);
>  }
> 
> +void hvm_emulate_init_per_insn(
> +    struct hvm_emulate_ctxt *hvmemul_ctxt,
> +    const unsigned char *insn_buf,
> +    unsigned int insn_bytes)
> +{
> +    struct vcpu *curr = current;
> +    unsigned int pfec = PFEC_page_present;
> +    unsigned long addr;
> +
> +    if ( hvm_long_mode_enabled(curr) &&
> +         hvmemul_ctxt->seg_reg[x86_seg_cs].attr.fields.l )
> +    {
> +        hvmemul_ctxt->ctxt.addr_size = hvmemul_ctxt->ctxt.sp_size = 64;
> +    }
> +    else
> +    {
> +        hvmemul_ctxt->ctxt.addr_size =
> +            hvmemul_ctxt->seg_reg[x86_seg_cs].attr.fields.db ? 32 : 16;
> +        hvmemul_ctxt->ctxt.sp_size =
> +            hvmemul_ctxt->seg_reg[x86_seg_ss].attr.fields.db ? 32 : 16;
> +    }
> +
> +    if ( hvmemul_ctxt->seg_reg[x86_seg_ss].attr.fields.dpl == 3 )
> +        pfec |= PFEC_user_mode;
> +
> +    hvmemul_ctxt->insn_buf_eip = hvmemul_ctxt->ctxt.regs->eip;
> +    if ( !insn_bytes )
> +    {
> +        hvmemul_ctxt->insn_buf_bytes =
> +            hvm_get_insn_bytes(curr, hvmemul_ctxt->insn_buf) ?:
> +            (hvm_virtual_to_linear_addr(x86_seg_cs,
> +                                        &hvmemul_ctxt->seg_reg[x86_seg_cs],
> +                                        hvmemul_ctxt->insn_buf_eip,
> +                                        sizeof(hvmemul_ctxt->insn_buf),
> +                                        hvm_access_insn_fetch,
> +                                        hvmemul_ctxt->ctxt.addr_size,
> +                                        &addr) &&
> +             hvm_fetch_from_guest_virt_nofault(hvmemul_ctxt->insn_buf,
> addr,
> +                                               sizeof(hvmemul_ctxt->insn_buf),
> +                                               pfec) == HVMCOPY_okay) ?
> +            sizeof(hvmemul_ctxt->insn_buf) : 0;
> +    }
> +    else
> +    {
> +        hvmemul_ctxt->insn_buf_bytes = insn_bytes;
> +        memcpy(hvmemul_ctxt->insn_buf, insn_buf, insn_bytes);
> +    }
> +
> +    hvmemul_ctxt->exn_pending = 0;
> +}
> +
>  void hvm_emulate_writeback(
>      struct hvm_emulate_ctxt *hvmemul_ctxt)
>  {
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index f76dd90..25dc759 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -4058,7 +4058,7 @@ void hvm_ud_intercept(struct cpu_user_regs
> *regs)
>  {
>      struct hvm_emulate_ctxt ctxt;
> 
> -    hvm_emulate_prepare(&ctxt, regs);
> +    hvm_emulate_init_once(&ctxt, regs);
> 
>      if ( opt_hvm_fep )
>      {
> diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
> index 1e7a5f9..7305801 100644
> --- a/xen/arch/x86/hvm/io.c
> +++ b/xen/arch/x86/hvm/io.c
> @@ -87,7 +87,7 @@ int handle_mmio(void)
> 
>      ASSERT(!is_pvh_vcpu(curr));
> 
> -    hvm_emulate_prepare(&ctxt, guest_cpu_user_regs());
> +    hvm_emulate_init_once(&ctxt, guest_cpu_user_regs());
> 
>      rc = hvm_emulate_one(&ctxt);
> 
> diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
> index d2245e2..88071ab 100644
> --- a/xen/arch/x86/hvm/ioreq.c
> +++ b/xen/arch/x86/hvm/ioreq.c
> @@ -167,7 +167,7 @@ bool_t handle_hvm_io_completion(struct vcpu *v)
>      {
>          struct hvm_emulate_ctxt ctxt;
> 
> -        hvm_emulate_prepare(&ctxt, guest_cpu_user_regs());
> +        hvm_emulate_init_once(&ctxt, guest_cpu_user_regs());
>          vmx_realmode_emulate_one(&ctxt);
>          hvm_emulate_writeback(&ctxt);
> 
> diff --git a/xen/arch/x86/hvm/svm/emulate.c
> b/xen/arch/x86/hvm/svm/emulate.c
> index a5545ea..9cdbe9e 100644
> --- a/xen/arch/x86/hvm/svm/emulate.c
> +++ b/xen/arch/x86/hvm/svm/emulate.c
> @@ -107,8 +107,8 @@ int __get_instruction_length_from_list(struct vcpu
> *v,
>  #endif
> 
>      ASSERT(v == current);
> -    hvm_emulate_prepare(&ctxt, guest_cpu_user_regs());
> -    hvm_emulate_init(&ctxt, NULL, 0);
> +    hvm_emulate_init_once(&ctxt, guest_cpu_user_regs());
> +    hvm_emulate_init_per_insn(&ctxt, NULL, 0);
>      state = x86_decode_insn(&ctxt.ctxt, hvmemul_insn_fetch);
>      if ( IS_ERR_OR_NULL(state) )
>          return 0;
> diff --git a/xen/arch/x86/hvm/vmx/realmode.c
> b/xen/arch/x86/hvm/vmx/realmode.c
> index e83a61f..9002638 100644
> --- a/xen/arch/x86/hvm/vmx/realmode.c
> +++ b/xen/arch/x86/hvm/vmx/realmode.c
> @@ -179,7 +179,7 @@ void vmx_realmode(struct cpu_user_regs *regs)
>      if ( intr_info & INTR_INFO_VALID_MASK )
>          __vmwrite(VM_ENTRY_INTR_INFO, 0);
> 
> -    hvm_emulate_prepare(&hvmemul_ctxt, regs);
> +    hvm_emulate_init_once(&hvmemul_ctxt, regs);
> 
>      /* Only deliver interrupts into emulated real mode. */
>      if ( !(curr->arch.hvm_vcpu.guest_cr[0] & X86_CR0_PE) &&
> diff --git a/xen/include/asm-x86/hvm/emulate.h b/xen/include/asm-
> x86/hvm/emulate.h
> index f610673..d4186a2 100644
> --- a/xen/include/asm-x86/hvm/emulate.h
> +++ b/xen/include/asm-x86/hvm/emulate.h
> @@ -51,10 +51,12 @@ int hvm_emulate_one_no_write(
>  void hvm_emulate_one_vm_event(enum emul_kind kind,
>      unsigned int trapnr,
>      unsigned int errcode);
> -void hvm_emulate_prepare(
> +/* Must be called once to set up hvmemul state. */
> +void hvm_emulate_init_once(
>      struct hvm_emulate_ctxt *hvmemul_ctxt,
>      struct cpu_user_regs *regs);
> -void hvm_emulate_init(
> +/* Must be called once before each instruction emulated. */
> +void hvm_emulate_init_per_insn(
>      struct hvm_emulate_ctxt *hvmemul_ctxt,
>      const unsigned char *insn_buf,
>      unsigned int insn_bytes);
> --
> 2.1.4
Wei Liu Nov. 23, 2016, 3:53 p.m. UTC | #2
On Wed, Nov 23, 2016 at 03:38:44PM +0000, Andrew Cooper wrote:
>  * Move hvm_emulate_init() to immediately hvm_emulate_prepare(), as they are
>    very closely related.
>  * Rename hvm_emulate_prepare() to hvm_emulate_init_once() and
>    hvm_emulate_init() to hvm_emulate_init_per_insn() to make it clearer how to
>    and when to use them.
> 
> No functional change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
Jan Beulich Nov. 23, 2016, 4:40 p.m. UTC | #3
>>> On 23.11.16 at 16:38, <andrew.cooper3@citrix.com> wrote:
> * Move hvm_emulate_init() to immediately hvm_emulate_prepare(), as they are
>    very closely related.
>  * Rename hvm_emulate_prepare() to hvm_emulate_init_once() and
>    hvm_emulate_init() to hvm_emulate_init_per_insn() to make it clearer how to
>    and when to use them.
> 
> No functional change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Reviewed-by: Jan Beulich <jbeulich@suse.com>
with one further cosmetic request:

> @@ -2006,6 +1956,57 @@ void hvm_emulate_prepare(
>      hvmemul_get_seg_reg(x86_seg_ss, hvmemul_ctxt);
>  }
>  
> +void hvm_emulate_init_per_insn(
> +    struct hvm_emulate_ctxt *hvmemul_ctxt,
> +    const unsigned char *insn_buf,
> +    unsigned int insn_bytes)
> +{
> +    struct vcpu *curr = current;
> +    unsigned int pfec = PFEC_page_present;
> +    unsigned long addr;
> +
> +    if ( hvm_long_mode_enabled(curr) &&
> +         hvmemul_ctxt->seg_reg[x86_seg_cs].attr.fields.l )
> +    {
> +        hvmemul_ctxt->ctxt.addr_size = hvmemul_ctxt->ctxt.sp_size = 64;
> +    }

Please consider dropping the stray braces here.

Jan
Andrew Cooper Nov. 23, 2016, 4:41 p.m. UTC | #4
On 23/11/16 16:41, Boris Ostrovsky wrote:
> On 11/23/2016 10:38 AM, Andrew Cooper wrote:
>>  * Move hvm_emulate_init() to immediately hvm_emulate_prepare(), as they are
>>    very closely related.
>>  * Rename hvm_emulate_prepare() to hvm_emulate_init_once() and
>>    hvm_emulate_init() to hvm_emulate_init_per_insn() to make it clearer how to
>>    and when to use them.
>>
>> No functional change.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
>> ---
>> CC: Jan Beulich <JBeulich@suse.com>
>> CC: Paul Durrant <paul.durrant@citrix.com>
>> CC: Jun Nakajima <jun.nakajima@intel.com>
>> CC: Kevin Tian <kevin.tian@intel.com>
>> CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>> CC: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
>> CC: Wei Liu <wei.liu2@citrix.com>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>
> (although I am having trouble parsing the first bullet in the commit
> message)

Ah "to immediately after".  I will fix up the text.

~Andrew
Boris Ostrovsky Nov. 23, 2016, 4:41 p.m. UTC | #5
On 11/23/2016 10:38 AM, Andrew Cooper wrote:
>  * Move hvm_emulate_init() to immediately hvm_emulate_prepare(), as they are
>    very closely related.
>  * Rename hvm_emulate_prepare() to hvm_emulate_init_once() and
>    hvm_emulate_init() to hvm_emulate_init_per_insn() to make it clearer how to
>    and when to use them.
>
> No functional change.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> ---
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Paul Durrant <paul.durrant@citrix.com>
> CC: Jun Nakajima <jun.nakajima@intel.com>
> CC: Kevin Tian <kevin.tian@intel.com>
> CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> CC: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> CC: Wei Liu <wei.liu2@citrix.com>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

(although I am having trouble parsing the first bullet in the commit
message)
Tian, Kevin Nov. 24, 2016, 6:16 a.m. UTC | #6
> From: Andrew Cooper [mailto:andrew.cooper3@citrix.com]
> Sent: Wednesday, November 23, 2016 11:39 PM
> 
>  * Move hvm_emulate_init() to immediately hvm_emulate_prepare(), as they are
>    very closely related.
>  * Rename hvm_emulate_prepare() to hvm_emulate_init_once() and
>    hvm_emulate_init() to hvm_emulate_init_per_insn() to make it clearer how to
>    and when to use them.
> 
> No functional change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

reviewed-by: Kevin Tian <kevin.tian@intel.com>

Patch
diff mbox

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index e9b8f8c..3ab0e8e 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -1755,57 +1755,6 @@  static const struct x86_emulate_ops hvm_emulate_ops_no_write = {
     .vmfunc        = hvmemul_vmfunc,
 };
 
-void hvm_emulate_init(
-    struct hvm_emulate_ctxt *hvmemul_ctxt,
-    const unsigned char *insn_buf,
-    unsigned int insn_bytes)
-{
-    struct vcpu *curr = current;
-    unsigned int pfec = PFEC_page_present;
-    unsigned long addr;
-
-    if ( hvm_long_mode_enabled(curr) &&
-         hvmemul_ctxt->seg_reg[x86_seg_cs].attr.fields.l )
-    {
-        hvmemul_ctxt->ctxt.addr_size = hvmemul_ctxt->ctxt.sp_size = 64;
-    }
-    else
-    {
-        hvmemul_ctxt->ctxt.addr_size =
-            hvmemul_ctxt->seg_reg[x86_seg_cs].attr.fields.db ? 32 : 16;
-        hvmemul_ctxt->ctxt.sp_size =
-            hvmemul_ctxt->seg_reg[x86_seg_ss].attr.fields.db ? 32 : 16;
-    }
-
-    if ( hvmemul_ctxt->seg_reg[x86_seg_ss].attr.fields.dpl == 3 )
-        pfec |= PFEC_user_mode;
-
-    hvmemul_ctxt->insn_buf_eip = hvmemul_ctxt->ctxt.regs->eip;
-    if ( !insn_bytes )
-    {
-        hvmemul_ctxt->insn_buf_bytes =
-            hvm_get_insn_bytes(curr, hvmemul_ctxt->insn_buf) ?:
-            (hvm_virtual_to_linear_addr(x86_seg_cs,
-                                        &hvmemul_ctxt->seg_reg[x86_seg_cs],
-                                        hvmemul_ctxt->insn_buf_eip,
-                                        sizeof(hvmemul_ctxt->insn_buf),
-                                        hvm_access_insn_fetch,
-                                        hvmemul_ctxt->ctxt.addr_size,
-                                        &addr) &&
-             hvm_fetch_from_guest_virt_nofault(hvmemul_ctxt->insn_buf, addr,
-                                               sizeof(hvmemul_ctxt->insn_buf),
-                                               pfec) == HVMCOPY_okay) ?
-            sizeof(hvmemul_ctxt->insn_buf) : 0;
-    }
-    else
-    {
-        hvmemul_ctxt->insn_buf_bytes = insn_bytes;
-        memcpy(hvmemul_ctxt->insn_buf, insn_buf, insn_bytes);
-    }
-
-    hvmemul_ctxt->exn_pending = 0;
-}
-
 static int _hvm_emulate_one(struct hvm_emulate_ctxt *hvmemul_ctxt,
     const struct x86_emulate_ops *ops)
 {
@@ -1815,7 +1764,8 @@  static int _hvm_emulate_one(struct hvm_emulate_ctxt *hvmemul_ctxt,
     struct hvm_vcpu_io *vio = &curr->arch.hvm_vcpu.hvm_io;
     int rc;
 
-    hvm_emulate_init(hvmemul_ctxt, vio->mmio_insn, vio->mmio_insn_bytes);
+    hvm_emulate_init_per_insn(hvmemul_ctxt, vio->mmio_insn,
+                              vio->mmio_insn_bytes);
 
     vio->mmio_retry = 0;
 
@@ -1915,7 +1865,7 @@  int hvm_emulate_one_mmio(unsigned long mfn, unsigned long gla)
     else
         ops = &hvm_ro_emulate_ops_mmio;
 
-    hvm_emulate_prepare(&ctxt, guest_cpu_user_regs());
+    hvm_emulate_init_once(&ctxt, guest_cpu_user_regs());
     ctxt.ctxt.data = &mmio_ro_ctxt;
     rc = _hvm_emulate_one(&ctxt, ops);
     switch ( rc )
@@ -1940,7 +1890,7 @@  void hvm_emulate_one_vm_event(enum emul_kind kind, unsigned int trapnr,
     struct hvm_emulate_ctxt ctx = {{ 0 }};
     int rc;
 
-    hvm_emulate_prepare(&ctx, guest_cpu_user_regs());
+    hvm_emulate_init_once(&ctx, guest_cpu_user_regs());
 
     switch ( kind )
     {
@@ -1992,7 +1942,7 @@  void hvm_emulate_one_vm_event(enum emul_kind kind, unsigned int trapnr,
     hvm_emulate_writeback(&ctx);
 }
 
-void hvm_emulate_prepare(
+void hvm_emulate_init_once(
     struct hvm_emulate_ctxt *hvmemul_ctxt,
     struct cpu_user_regs *regs)
 {
@@ -2006,6 +1956,57 @@  void hvm_emulate_prepare(
     hvmemul_get_seg_reg(x86_seg_ss, hvmemul_ctxt);
 }
 
+void hvm_emulate_init_per_insn(
+    struct hvm_emulate_ctxt *hvmemul_ctxt,
+    const unsigned char *insn_buf,
+    unsigned int insn_bytes)
+{
+    struct vcpu *curr = current;
+    unsigned int pfec = PFEC_page_present;
+    unsigned long addr;
+
+    if ( hvm_long_mode_enabled(curr) &&
+         hvmemul_ctxt->seg_reg[x86_seg_cs].attr.fields.l )
+    {
+        hvmemul_ctxt->ctxt.addr_size = hvmemul_ctxt->ctxt.sp_size = 64;
+    }
+    else
+    {
+        hvmemul_ctxt->ctxt.addr_size =
+            hvmemul_ctxt->seg_reg[x86_seg_cs].attr.fields.db ? 32 : 16;
+        hvmemul_ctxt->ctxt.sp_size =
+            hvmemul_ctxt->seg_reg[x86_seg_ss].attr.fields.db ? 32 : 16;
+    }
+
+    if ( hvmemul_ctxt->seg_reg[x86_seg_ss].attr.fields.dpl == 3 )
+        pfec |= PFEC_user_mode;
+
+    hvmemul_ctxt->insn_buf_eip = hvmemul_ctxt->ctxt.regs->eip;
+    if ( !insn_bytes )
+    {
+        hvmemul_ctxt->insn_buf_bytes =
+            hvm_get_insn_bytes(curr, hvmemul_ctxt->insn_buf) ?:
+            (hvm_virtual_to_linear_addr(x86_seg_cs,
+                                        &hvmemul_ctxt->seg_reg[x86_seg_cs],
+                                        hvmemul_ctxt->insn_buf_eip,
+                                        sizeof(hvmemul_ctxt->insn_buf),
+                                        hvm_access_insn_fetch,
+                                        hvmemul_ctxt->ctxt.addr_size,
+                                        &addr) &&
+             hvm_fetch_from_guest_virt_nofault(hvmemul_ctxt->insn_buf, addr,
+                                               sizeof(hvmemul_ctxt->insn_buf),
+                                               pfec) == HVMCOPY_okay) ?
+            sizeof(hvmemul_ctxt->insn_buf) : 0;
+    }
+    else
+    {
+        hvmemul_ctxt->insn_buf_bytes = insn_bytes;
+        memcpy(hvmemul_ctxt->insn_buf, insn_buf, insn_bytes);
+    }
+
+    hvmemul_ctxt->exn_pending = 0;
+}
+
 void hvm_emulate_writeback(
     struct hvm_emulate_ctxt *hvmemul_ctxt)
 {
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index f76dd90..25dc759 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4058,7 +4058,7 @@  void hvm_ud_intercept(struct cpu_user_regs *regs)
 {
     struct hvm_emulate_ctxt ctxt;
 
-    hvm_emulate_prepare(&ctxt, regs);
+    hvm_emulate_init_once(&ctxt, regs);
 
     if ( opt_hvm_fep )
     {
diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
index 1e7a5f9..7305801 100644
--- a/xen/arch/x86/hvm/io.c
+++ b/xen/arch/x86/hvm/io.c
@@ -87,7 +87,7 @@  int handle_mmio(void)
 
     ASSERT(!is_pvh_vcpu(curr));
 
-    hvm_emulate_prepare(&ctxt, guest_cpu_user_regs());
+    hvm_emulate_init_once(&ctxt, guest_cpu_user_regs());
 
     rc = hvm_emulate_one(&ctxt);
 
diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
index d2245e2..88071ab 100644
--- a/xen/arch/x86/hvm/ioreq.c
+++ b/xen/arch/x86/hvm/ioreq.c
@@ -167,7 +167,7 @@  bool_t handle_hvm_io_completion(struct vcpu *v)
     {
         struct hvm_emulate_ctxt ctxt;
 
-        hvm_emulate_prepare(&ctxt, guest_cpu_user_regs());
+        hvm_emulate_init_once(&ctxt, guest_cpu_user_regs());
         vmx_realmode_emulate_one(&ctxt);
         hvm_emulate_writeback(&ctxt);
 
diff --git a/xen/arch/x86/hvm/svm/emulate.c b/xen/arch/x86/hvm/svm/emulate.c
index a5545ea..9cdbe9e 100644
--- a/xen/arch/x86/hvm/svm/emulate.c
+++ b/xen/arch/x86/hvm/svm/emulate.c
@@ -107,8 +107,8 @@  int __get_instruction_length_from_list(struct vcpu *v,
 #endif
 
     ASSERT(v == current);
-    hvm_emulate_prepare(&ctxt, guest_cpu_user_regs());
-    hvm_emulate_init(&ctxt, NULL, 0);
+    hvm_emulate_init_once(&ctxt, guest_cpu_user_regs());
+    hvm_emulate_init_per_insn(&ctxt, NULL, 0);
     state = x86_decode_insn(&ctxt.ctxt, hvmemul_insn_fetch);
     if ( IS_ERR_OR_NULL(state) )
         return 0;
diff --git a/xen/arch/x86/hvm/vmx/realmode.c b/xen/arch/x86/hvm/vmx/realmode.c
index e83a61f..9002638 100644
--- a/xen/arch/x86/hvm/vmx/realmode.c
+++ b/xen/arch/x86/hvm/vmx/realmode.c
@@ -179,7 +179,7 @@  void vmx_realmode(struct cpu_user_regs *regs)
     if ( intr_info & INTR_INFO_VALID_MASK )
         __vmwrite(VM_ENTRY_INTR_INFO, 0);
 
-    hvm_emulate_prepare(&hvmemul_ctxt, regs);
+    hvm_emulate_init_once(&hvmemul_ctxt, regs);
 
     /* Only deliver interrupts into emulated real mode. */
     if ( !(curr->arch.hvm_vcpu.guest_cr[0] & X86_CR0_PE) &&
diff --git a/xen/include/asm-x86/hvm/emulate.h b/xen/include/asm-x86/hvm/emulate.h
index f610673..d4186a2 100644
--- a/xen/include/asm-x86/hvm/emulate.h
+++ b/xen/include/asm-x86/hvm/emulate.h
@@ -51,10 +51,12 @@  int hvm_emulate_one_no_write(
 void hvm_emulate_one_vm_event(enum emul_kind kind,
     unsigned int trapnr,
     unsigned int errcode);
-void hvm_emulate_prepare(
+/* Must be called once to set up hvmemul state. */
+void hvm_emulate_init_once(
     struct hvm_emulate_ctxt *hvmemul_ctxt,
     struct cpu_user_regs *regs);
-void hvm_emulate_init(
+/* Must be called once before each instruction emulated. */
+void hvm_emulate_init_per_insn(
     struct hvm_emulate_ctxt *hvmemul_ctxt,
     const unsigned char *insn_buf,
     unsigned int insn_bytes);