Re: [Qemu-devel] [PATCH v3 4/6] target-i386: Remove unsupported bits from all CPU models

[Andreas Färber]

Am 03.10.2014 um 21:39 schrieb Eduardo Habkost:
> The following CPU features were never supported by neither TCG or KVM,
> so they are useless on the CPU model definitions, today:
> 
>  * CPUID_DTS (DS)
>  * CPUID_HT
>  * CPUID_TM
>  * CPUID_PBE
>  * CPUID_EXT_DTES64
>  * CPUID_EXT_DSCPL
>  * CPUID_EXT_EST
>  * CPUID_EXT_TM2
>  * CPUID_EXT_XTPR
>  * CPUID_EXT_PDCM
>  * CPUID_SVM_LBRV
> 
> As using "enforce" mode is the only way to ensure guest ABI doesn't
> change when moving to a different host, we should make "enforce" mode
> the default or at least encourage management software to always use it.
> 
> In turn, to make "enforce" usable, we need CPU models that work without
> always requiring some features to be explicitly disabled. This patch
> removes the above features from all CPU model definitions.
> 
> We won't need any machine-type compat code for those changes, because it
> is impossible to have existing VMs with those features enabled.
> 
> Signed-off-by: Eduardo Habkost <address@hidden>
> Cc: Aurelien Jarno <address@hidden>
> ---
> Changes v1 -> v2:
> * Trivial typo fix in comment
> ---
>  target-i386/cpu.c | 33 ++++++++++++++++++++-------------
>  1 file changed, 20 insertions(+), 13 deletions(-)
> 
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 4119fca..1e9fff9 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -681,10 +681,11 @@ static X86CPUDefinition builtin_x86_defs[] = {
>          .family = 16,
>          .model = 2,
>          .stepping = 3,
> +        /* Missing: CPUID_HT */
>          .features[FEAT_1_EDX] =
>              PPRO_FEATURES |
>              CPUID_MTRR | CPUID_CLFLUSH | CPUID_MCA |
> -            CPUID_PSE36 | CPUID_VME | CPUID_HT,
> +            CPUID_PSE36 | CPUID_VME,
>          .features[FEAT_1_ECX] =
>              CPUID_EXT_SSE3 | CPUID_EXT_MONITOR | CPUID_EXT_CX16 |
>              CPUID_EXT_POPCNT,
[snip]

I'm okay with retaining these as comments. Anyone any objections?

Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg