[Qemu-devel] [PATCH 0/2] target-i386: tcg: Handle clflushopt/clwb/pcommit instructions

[Qemu-devel] [PATCH 0/2] target-i386: tcg: Handle clflushopt/clwb/pcommit instructions

[Eduardo Habkost]

This series makes TCG accept the clwb instruction, and make it check the right
CPUID bits when handling clflushopt and pcommit.

Tested using the kvm-unit-test patch I sent earlier today:
  Subject: [kvm-unit-test RFC] x86: Memory instructions test case
  Message-Id: <1446672079-8549-1-git-send-email-ehabkost@redhat.com>

Eduardo Habkost (2):
  target-i386: tcg: Accept clwb instruction
  target-i386: tcg: Check right CPUID bits for clflushopt/pcommit

 target-i386/translate.c | 39 +++++++++++++++++++++++++++++++--------
 1 file changed, 31 insertions(+), 8 deletions(-)

-- 
2.1.0

[Qemu-devel] [PATCH 1/2] target-i386: tcg: Accept clwb instruction

[Eduardo Habkost]

Accept the clwb instruction (66 0F AE /6) if its corresponding feature
flag is enabled on CPUID[7].

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/translate.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/target-i386/translate.c b/target-i386/translate.c
index b400d24..bac1685 100644
--- a/target-i386/translate.c
+++ b/target-i386/translate.c
@@ -7716,10 +7716,21 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
             }
             break;
         case 5: /* lfence */
-        case 6: /* mfence */
             if ((modrm & 0xc7) != 0xc0 || !(s->cpuid_features & CPUID_SSE2))
                 goto illegal_op;
             break;
+        case 6: /* mfence/clwb */
+            if (s->prefix & PREFIX_DATA) {
+                /* clwb */
+                if (!(s->cpuid_7_0_ebx_features & CPUID_7_0_EBX_CLWB))
+                    goto illegal_op;
+                gen_lea_modrm(env, s, modrm);
+            } else {
+                /* mfence */
+                if ((modrm & 0xc7) != 0xc0 || !(s->cpuid_features & CPUID_SSE2))
+                    goto illegal_op;
+            }
+            break;
         case 7: /* sfence / clflush */
             if ((modrm & 0xc7) == 0xc0) {
                 /* sfence */
-- 
2.1.0

[Qemu-devel] [PATCH 2/2] target-i386: tcg: Check right CPUID bits for clflushopt/pcommit

[Eduardo Habkost]

Detect the clflushopt and pcommit instructions and check their
corresponding feature flags, instead of checking CPUID_SSE and
CPUID_CLFLUSH.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/translate.c | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/target-i386/translate.c b/target-i386/translate.c
index bac1685..a938967 100644
--- a/target-i386/translate.c
+++ b/target-i386/translate.c
@@ -7731,16 +7731,28 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
                     goto illegal_op;
             }
             break;
-        case 7: /* sfence / clflush */
+        case 7: /* sfence / clflush / clflushopt / pcommit */
             if ((modrm & 0xc7) == 0xc0) {
-                /* sfence */
-                /* XXX: also check for cpuid_ext2_features & CPUID_EXT2_EMMX */
-                if (!(s->cpuid_features & CPUID_SSE))
-                    goto illegal_op;
+                if (s->prefix & PREFIX_DATA) {
+                    /* pcommit */
+                    if (!(s->cpuid_7_0_ebx_features & CPUID_7_0_EBX_PCOMMIT))
+                        goto illegal_op;
+                } else {
+                    /* sfence */
+                    /* XXX: also check for cpuid_ext2_features & CPUID_EXT2_EMMX */
+                    if (!(s->cpuid_features & CPUID_SSE))
+                        goto illegal_op;
+                }
             } else {
-                /* clflush */
-                if (!(s->cpuid_features & CPUID_CLFLUSH))
-                    goto illegal_op;
+                if (s->prefix & PREFIX_DATA) {
+                    /* clflushopt */
+                    if (!(s->cpuid_7_0_ebx_features & CPUID_7_0_EBX_CLFLUSHOPT))
+                        goto illegal_op;
+                } else {
+                    /* clflush */
+                    if (!(s->cpuid_features & CPUID_CLFLUSH))
+                        goto illegal_op;
+                }
                 gen_lea_modrm(env, s, modrm);
             }
             break;
-- 
2.1.0

Re: [Qemu-devel] [PATCH 1/2] target-i386: tcg: Accept clwb instruction

[Richard Henderson]

On 11/04/2015 10:24 PM, Eduardo Habkost wrote:
> Accept the clwb instruction (66 0F AE /6) if its corresponding feature
> flag is enabled on CPUID[7].
>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
>   target-i386/translate.c | 13 ++++++++++++-
>   1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/target-i386/translate.c b/target-i386/translate.c
> index b400d24..bac1685 100644
> --- a/target-i386/translate.c
> +++ b/target-i386/translate.c
> @@ -7716,10 +7716,21 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
>               }
>               break;
>           case 5: /* lfence */
> -        case 6: /* mfence */
>               if ((modrm & 0xc7) != 0xc0 || !(s->cpuid_features & CPUID_SSE2))
>                   goto illegal_op;
>               break;
> +        case 6: /* mfence/clwb */
> +            if (s->prefix & PREFIX_DATA) {
> +                /* clwb */
> +                if (!(s->cpuid_7_0_ebx_features & CPUID_7_0_EBX_CLWB))
> +                    goto illegal_op;
> +                gen_lea_modrm(env, s, modrm);

You should use gen_nop_modrm here, since we're not going to do anything with 
the address.  Otherwise,

Reviewed-by: Richard Henderson <rth@twiddle.net>


r~

Re: [Qemu-devel] [PATCH 2/2] target-i386: tcg: Check right CPUID bits for clflushopt/pcommit

[Richard Henderson]

On 11/04/2015 10:24 PM, Eduardo Habkost wrote:
> Detect the clflushopt and pcommit instructions and check their
> corresponding feature flags, instead of checking CPUID_SSE and
> CPUID_CLFLUSH.
>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
>   target-i386/translate.c | 28 ++++++++++++++++++++--------
>   1 file changed, 20 insertions(+), 8 deletions(-)

Reviewed-by: Richard Henderson <rth@twiddle.net>


r~

Re: [Qemu-devel] [PATCH 1/2] target-i386: tcg: Accept clwb instruction

[Eduardo Habkost]

On Fri, Nov 06, 2015 at 12:04:56PM +0100, Richard Henderson wrote:
> On 11/04/2015 10:24 PM, Eduardo Habkost wrote:
> >Accept the clwb instruction (66 0F AE /6) if its corresponding feature
> >flag is enabled on CPUID[7].
> >
> >Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> >---
> >  target-i386/translate.c | 13 ++++++++++++-
> >  1 file changed, 12 insertions(+), 1 deletion(-)
> >
> >diff --git a/target-i386/translate.c b/target-i386/translate.c
> >index b400d24..bac1685 100644
> >--- a/target-i386/translate.c
> >+++ b/target-i386/translate.c
> >@@ -7716,10 +7716,21 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
> >              }
> >              break;
> >          case 5: /* lfence */
> >-        case 6: /* mfence */
> >              if ((modrm & 0xc7) != 0xc0 || !(s->cpuid_features & CPUID_SSE2))
> >                  goto illegal_op;
> >              break;
> >+        case 6: /* mfence/clwb */
> >+            if (s->prefix & PREFIX_DATA) {
> >+                /* clwb */
> >+                if (!(s->cpuid_7_0_ebx_features & CPUID_7_0_EBX_CLWB))
> >+                    goto illegal_op;
> >+                gen_lea_modrm(env, s, modrm);
> 
> You should use gen_nop_modrm here, since we're not going to do anything with
> the address.  Otherwise,
> 
> Reviewed-by: Richard Henderson <rth@twiddle.net>

Thanks! BTW, clflush uses gen_lea_modrm() too, does it do anything with
the address somewhere else?

-- 
Eduardo

Re: [Qemu-devel] [PATCH 1/2] target-i386: tcg: Accept clwb instruction

[Richard Henderson]

On 11/06/2015 02:59 PM, Eduardo Habkost wrote:
> Thanks! BTW, clflush uses gen_lea_modrm() too, does it do anything with
> the address somewhere else?

Nope.  It probably pre-dates the introduction of gen_nop_modrm.


r~