From: Alexander Graf <agraf@suse.de>
To: Alexey Kardashevskiy <aik@ozlabs.ru>, qemu-devel@nongnu.org
Cc: qemu-ppc@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] target-ppc: Fix number of threads per core limit
Date: Thu, 10 Jul 2014 12:33:37 +0200 [thread overview]
Message-ID: <53BE6C01.10001@suse.de> (raw)
In-Reply-To: <1404916856-12567-1-git-send-email-aik@ozlabs.ru>
On 09.07.14 16:40, Alexey Kardashevskiy wrote:
> The number of threads per core is different for POWER6/7/8 CPUs.
> Guest systems do not expect to see more threads per core than
> a specific CPU supports so we need to limit this number.
> This limit is implemented by ppc_get_compat_smt_threads().
>
> However it has a problem as it checks for PCR (Processor Compatibility
> Register) mask, 2.05 means 2 threads per core, 2.06 - 4 threads.
> For POWER8 one would expect PCR_COMPAT_2_07 bit set and
> ppc_get_compat_smt_threads() checking for it to return 8 threads
> per core. But the latest PowerISA spec now is 2.07 and there is
> no 2.07 compatibility mode defined, QEMU does not define it either
> (will be in PowerISA 2.08).
>
> Instead of relying on a PCR mask, this uses kvmppc_smt_threads()
> which returns the maximum supported threads number for KVM or
> 1 for TCG.
>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Thanks, applied to ppc-next (for 2.1).
Alex
prev parent reply other threads:[~2014-07-10 10:33 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-09 14:40 [Qemu-devel] [PATCH] target-ppc: Fix number of threads per core limit Alexey Kardashevskiy
2014-07-10 10:33 ` Alexander Graf [this message]
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