Re: [Xen-devel] [PATCH 1/3] x86/hvm: Revert 80ecb40362365ba77e68fc609de8bd3b7208ae19

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 06.03.14 at 19:31, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
> The Solaris bug that commit 80ecb40362365ba77e68fc609de8bd3b7208ae19 
> addressed
> has been fixed and backported to earlier releases.

I don't think this is sufficient justification for the revert: Suppose
someone's still running an un-patched Solaris guest (for a cloud
provider this may even be unknowingly) and then updates the
hypervisor (i.e. by migrating the guest to an updated host). I
can see why you want this reverted for the subsequent patches,
but I'm afraid a different solution will need to be found (if nothing
else, via explicit guest config option).

Jan

> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> ---
>  xen/arch/x86/traps.c |   11 ++---------
>  1 files changed, 2 insertions(+), 9 deletions(-)
> 
> diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
> index c462317..d8f83a0 100644
> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -677,23 +677,16 @@ int cpuid_hypervisor_leaves( uint32_t idx, uint32_t 
> sub_idx,
>      struct domain *d = current->domain;
>      /* Optionally shift out of the way of Viridian architectural leaves. */
>      uint32_t base = is_viridian_domain(d) ? 0x40000100 : 0x40000000;
> -    uint32_t limit;
>  
>      idx -= base;
>  
> -    /*
> -     * Some Solaris PV drivers fail if max > base + 2. Help them out by
> -     * hiding the PVRDTSCP leaf if PVRDTSCP is disabled.
> -     */
> -    limit = (d->arch.tsc_mode < TSC_MODE_PVRDTSCP) ? 2 : 3;
> -
> -    if ( idx > limit ) 
> +    if ( idx > 3 ) 
>          return 0;
>  
>      switch ( idx )
>      {
>      case 0:
> -        *eax = base + limit; /* Largest leaf */
> +        *eax = base + 3; /* Largest leaf */
>          *ebx = XEN_CPUID_SIGNATURE_EBX;
>          *ecx = XEN_CPUID_SIGNATURE_ECX;
>          *edx = XEN_CPUID_SIGNATURE_EDX;
> -- 
> 1.7.1




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