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Re: [Qemu-devel] [PATCH 1/3] spapr: Disable ibm, pa-features HTM bit
From: |
David Gibson |
Subject: |
Re: [Qemu-devel] [PATCH 1/3] spapr: Disable ibm, pa-features HTM bit |
Date: |
Tue, 5 Jul 2016 15:51:33 +1000 |
User-agent: |
Mutt/1.6.1 (2016-04-27) |
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 <address@hidden>
Reviewed-by: David Gibson <address@hidden>
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
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- [Qemu-devel] [PATCH 0/3] Rework spapr: Better handling of ibm, pa-features TM bit, Sam Bobroff, 2016/07/05
- [Qemu-devel] [PATCH 3/3] spapr: Set ibm, pa-features HTM from KVM_CAP_PPC_HTM, Sam Bobroff, 2016/07/05
- [Qemu-devel] [PATCH 1/3] spapr: Disable ibm, pa-features HTM bit, Sam Bobroff, 2016/07/05
- Re: [Qemu-devel] [PATCH 1/3] spapr: Disable ibm, pa-features HTM bit,
David Gibson <=
- [Qemu-devel] [PATCH 2/3] Add KVM_CAP_PPC_HTM to linux/kvm.h, Sam Bobroff, 2016/07/05
- [Qemu-devel] [PATCH v2 0/3] Rework spapr: Better handling of ibm, pa-features TM bit, Sam Bobroff, 2016/07/06