Re: [PATCH] target/i386: Remove MPX support on Snowridge CPU model

[Eduardo Habkost]

On Fri, Oct 11, 2019 at 03:18:44PM +0800, Xiaoyao Li wrote:
> MPX support is being phased out by Intel. Following other CPU models
> like Skylake, Icelake and Cascadelake, do not enable it by default.
> 
> Signed-off-by: Xiaoyao Li <address@hidden>
> ---
> I'm not sure is there anyone already use Snowridge CPU model and whether to
> add it in pc_compat_4_1, since Snowridge has not been released yet.

We have a CPU model versioning mechanism now, please implement this using the
new system.  e.g.:

        .versions = (X86CPUVersionDefinition[]) {
            { .version = 1 },
            {
                .version = 2,
                .props = (PropValue[]) {
                    { "mpx", "off" },
                    { /* end of list */ }
                }
            },
            { /* end of list */ }
        }

Then machine-type compat properties won't be needed anymore.

> 
> ---
>  hw/i386/pc.c      | 4 +++-
>  target/i386/cpu.c | 1 -
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index bcda50efcc23..97eb7ac32588 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -105,7 +105,9 @@ struct hpet_fw_config hpet_cfg = {.count = UINT8_MAX};
>  /* Physical Address of PVH entry point read from kernel ELF NOTE */
>  static size_t pvh_start_addr;
>  
> -GlobalProperty pc_compat_4_1[] = {};
> +GlobalProperty pc_compat_4_1[] = {
> +    { "Snowridge" "-" TYPE_X86_CPU, "mpx", "on" },
> +};
>  const size_t pc_compat_4_1_len = G_N_ELEMENTS(pc_compat_4_1);
>  
>  GlobalProperty pc_compat_4_0[] = {};
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 44f1bbdcac76..885bea76205d 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -2762,7 +2762,6 @@ static X86CPUDefinition builtin_x86_defs[] = {
>              CPUID_7_0_EBX_FSGSBASE |
>              CPUID_7_0_EBX_SMEP |
>              CPUID_7_0_EBX_ERMS |
> -            CPUID_7_0_EBX_MPX |  /* missing bits 13, 15 */
>              CPUID_7_0_EBX_RDSEED |
>              CPUID_7_0_EBX_SMAP | CPUID_7_0_EBX_CLFLUSHOPT |
>              CPUID_7_0_EBX_CLWB |
> -- 
> 2.19.1
> 

-- 
Eduardo