Re: [Qemu-devel] [QEMU-PPC] [PATCH V2 1/2] target/ppc: Don't require private l1d cache on POWER8 for cap_ppc_safe_cache

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Jun 12, 2018 at 03:16:29PM +1000, Suraj Jitindar Singh wrote:
> For cap_ppc_safe_cache to be set to workaround, we require both a l1d
> cache flush instruction and private l1d cache.
> 
> On POWER8 don't require private l1d cache. This means a guest on a
> POWER8 machine can make use of the cache flush workarounds.
> 
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>

Applied to ppc-for-3.0, thanks.

> 
> ---
> 
> V1 -> V2:
> - Use mfpvr() to detect host type
> 
> ---
>  target/ppc/kvm.c | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index 2c0c34e125..7fe9d0126b 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -2412,11 +2412,28 @@ bool kvmppc_has_cap_mmu_hash_v3(void)
>      return cap_mmu_hash_v3;
>  }
>  
> +static bool kvmppc_power8_host(void)
> +{
> +    bool ret = false;
> +#ifdef TARGET_PPC64
> +    {
> +        uint32_t base_pvr = CPU_POWERPC_POWER_SERVER_MASK & mfpvr();
> +        ret = (base_pvr == CPU_POWERPC_POWER8E_BASE) ||
> +              (base_pvr == CPU_POWERPC_POWER8NVL_BASE) ||
> +              (base_pvr == CPU_POWERPC_POWER8_BASE);
> +    }
> +#endif /* TARGET_PPC64 */
> +    return ret;
> +}
> +
>  static int parse_cap_ppc_safe_cache(struct kvm_ppc_cpu_char c)
>  {
> +    bool l1d_thread_priv_req = !kvmppc_power8_host();
> +
>      if (~c.behaviour & c.behaviour_mask & H_CPU_BEHAV_L1D_FLUSH_PR) {
>          return 2;
> -    } else if ((c.character & c.character_mask & H_CPU_CHAR_L1D_THREAD_PRIV) &&
> +    } else if ((!l1d_thread_priv_req ||
> +                c.character & c.character_mask & H_CPU_CHAR_L1D_THREAD_PRIV) &&
>                 (c.character & c.character_mask
>                  & (H_CPU_CHAR_L1D_FLUSH_ORI30 | H_CPU_CHAR_L1D_FLUSH_TRIG2))) {
>          return 1;

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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