Re: [PATCH v2 3/4] target/i386: add the missing features for Icelake-Server CPU model

[Robert Hoo]

On Sat, 2020-03-28 at 11:06 +0800, Chenyi Qiang wrote:
> Add the SHA_NI and AVX512IFMA feature bits in FEAT_7_0_EBX, RDPID
> feature bit in FEAT_7_0_ECX and FSRM feature bit in FEAT_7_0_EDX.
> 
> Signed-off-by: Chenyi Qiang <address@hidden>
> ---
>  target/i386/cpu.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index b01421c6bb..babb074abf 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -3552,6 +3552,16 @@ static X86CPUDefinition builtin_x86_defs[] = {
>                      { /* end of list */ }
>                  },
>              },
> +            {
> +                .version = 3,
> +                .props = (PropValue[]) {
> +                    { "sha-ni", "on" },
> +                    { "avx512ifma", "on" },
> +                    { "rdpid", "on" },
> +                    { "fsrm", "on" },
> +                    { /* end of list */ }
> +                },
> +            },
>              { /* end of list */ }
I think these 4 new CPUIDs addition is to catch up latest 
https://software.intel.com/sites/default/files/managed/c5/15/architecture-instruction-set-extensions-programming-reference.pdf
 on updates.
This is actually fix to previous v1 definitions.
So my 2 cents:
1. add 1 more version: include v2's hle and rtm properties off
2. make the hle-rtm-disable inclusion version or this v3 default
version of icelake.
Anyway, v1 is not suitable for default choice.

Then questions comes to how to make non-v1 default.
Perhaps:

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 34b511f..d4eb3d6 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -5453,7 +5453,7 @@ static void
x86_register_cpudef_types(X86CPUDefinition *def)
     /* Unversioned model: */
     m = g_new0(X86CPUModel, 1);
     m->cpudef = def;
-    m->version = CPU_VERSION_AUTO;
+    m->version = CPU_VERSION_LATEST;
     m->is_alias = true;
     x86_register_cpu_model_type(def->name, m);

I think for builtin_x86_defs[] definitions, latest version is usually
preferable/suitable.
How would Paolo, Eduardo like it?
>          }
>      },