Subject: Re: [PATCH 1/3] spapr: Disable ibm, pa-features HTM bit

From: David Gibson <[email-masked]>
Date: Tue, 5 Jul 2016 15:51:33 +1000

On Tue, Jul 05, 2016 at 03:19:22PM +1000, Sam Bobroff wrote:
> There are a few issues with our handling of the ibm,pa-features
> HTM bit:
> 
> - We don't support transactional memory in PR KVM, so don't tell
>   the OS that we do.
> 
> - In full emulation we have a minimal implementation of HTM that always
>   fails, so for performance reasons lets not tell the OS that we
>   support it either.
> 
> - In HV KVM mode, we should mirror the host HTM enabled state by
>   checking a KVM capability or looking at the AT_HWCAP2 bit.
> 
> For now unconditionally disable it by removing HTM from the
> pa-features bits.  It will be re-enabled in a subsequent patch
> specifically for HV KVM.
> 
> Signed-off-by: Sam Bobroff <[email-masked]>

Reviewed-by: David Gibson <[email-masked]>

I'll hold off on merging until the rest of the series is ready, though.

> ---
>  hw/ppc/spapr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 78ebd9e..704aae7 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -635,7 +635,7 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, int offset,
>          0xf6, 0x1f, 0xc7, 0xc0, 0x80, 0xf0,
>          0x80, 0x00, 0x00, 0x00, 0x00, 0x00,
>          0x00, 0x00, 0x00, 0x00, 0x80, 0x00,
> -        0x80, 0x00, 0x80, 0x00, 0x80, 0x00 };
> +        0x80, 0x00, 0x80, 0x00, 0x00, 0x00 };
>      uint8_t *pa_features;
>      size_t pa_size;
>  

-- 
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