Re: [Qemu-devel] [PATCH 3/5] target-i386: remove vendor_override field from CPUX86State

[Andreas Färber]

Am 21.01.2013 15:06, schrieb Igor Mammedov:
> commit 8935499831312 makes cpuid return to guest host's vendor value
> instead of built-in one by default if kvm_enabled() == true and allows
> to override this behavior if 'vendor' is specified on -cpu command line.
> 
> But every time guest calls cpuid to get 'vendor' value, host's value is
> read again and again in default case.
> 
> It complicates semantic of vendor property and makes it harder to use.
> 
> Instead of reading 'vendor' value from host every time cpuid[vendor] is
> called, override 'vendor' value only once in cpu_x86_find_by_name(), when
> built-in CPU model is found and if(kvm_enabled() == true).
> 
> It provides the same default semantic
>  if (kvm_enabled() == true)  vendor = host's vendor
>  else vendor = built-in vendor
> 
> and then later:
>  if (custom vendor) vendor = custom vendor
> 
> 'vendor' value is overridden when user provides it on -cpu command line,
> and there isn't need in vendor_override field anymore, remove it.
> 
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
>  v4:
>    - rebased with "target-i386: move out CPU features initialization
>      in separate func" dropped. So remove vendor_override in
>      cpu_x86_register() instead.
>    - replace x86cpu_vendor_words2str() with x86_cpu_vendor_words2str()
>      due to renaming of the last in previous patch
> ---
>  target-i386/cpu.c |   27 ++++++++++++---------------
>  target-i386/cpu.h |    1 -
>  2 files changed, 12 insertions(+), 16 deletions(-)
> 
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 93da9b2..768ca69 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
[...]
> @@ -1283,6 +1280,18 @@ static int cpu_x86_find_by_name(x86_def_t 
> *x86_cpu_def, const char *name)
>          return -1;
>      } else {
>          memcpy(x86_cpu_def, def, sizeof(*def));
> +        /* sysenter isn't supported on compatibility mode on AMD, syscall
> +         * isn't supported in compatibility mode on Intel.
> +         * Normally we advertise the actual cpu vendor, but you can override
> +         * this using the 'vendor' property if you want to use KVM's
> +         * sysenter/syscall emulation in compatibility mode and when doing
> +         * cross vendor migration
> +         */
[snip]

Thanks, rebased and applied 2-3 to qom-cpu (rebreaking the text due to
new indentation and fixing a typo present in the original):
https://github.com/afaerber/qemu-cpu/commits/qom-cpu

Andreas


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