From: Nicholas Piggin <npiggin@gmail•com>
To: Paul Mackerras <paulus@ozlabs•org>
Cc: kvm-ppc@vger•kernel.org, "Anton Blanchard" <anton@linux•ibm.com>,
"Cédric Le Goater" <clg@kaod•org>,
linuxppc-dev@lists•ozlabs.org,
"David Gibson" <david@gibson•dropbear.id.au>
Subject: Re: [PATCH 3/3] powerpc/pseries: Add KVM guest doorbell restrictions
Date: Tue, 30 Jun 2020 15:35:08 +1000 [thread overview]
Message-ID: <1593495049.cacw882re0.astroid@bobo.none> (raw)
In-Reply-To: <20200630022713.GA618342@thinks.paulus.ozlabs.org>
Excerpts from Paul Mackerras's message of June 30, 2020 12:27 pm:
> On Sun, Jun 28, 2020 at 01:04:28AM +1000, Nicholas Piggin wrote:
>> KVM guests have certain restrictions and performance quirks when
>> using doorbells. This patch tests for KVM environment in doorbell
>> setup, and optimises IPI performance:
>>
>> - PowerVM guests may now use doorbells even if they are secure.
>>
>> - KVM guests no longer use doorbells if XIVE is available.
>
> It seems, from the fact that you completely remove
> kvm_para_available(), that you perhaps haven't tried building with
> CONFIG_KVM_GUEST=y.
It's still there and builds:
static inline int kvm_para_available(void)
{
return IS_ENABLED(CONFIG_KVM_GUEST) && is_kvm_guest();
}
but...
> Somewhat confusingly, that option is not used or
> needed when building for a PAPR guest (i.e. the "pseries" platform)
> but is used on non-IBM platforms using the "epapr" hypervisor
> interface.
... is_kvm_guest() returns false on !PSERIES now. Not intended
to break EPAPR. I'm not sure of a good way to share this between
EPAPR and PSERIES, I might just make a copy of it but I'll see.
Thanks,
Nick
next prev parent reply other threads:[~2020-06-30 5:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-27 15:04 [PATCH 0/3] powerpc/pseries: IPI doorbell improvements Nicholas Piggin
2020-06-27 15:04 ` [PATCH 1/3] powerpc: inline doorbell sending functions Nicholas Piggin
2020-06-27 19:46 ` kernel test robot
2020-06-30 1:31 ` Michael Ellerman
2020-06-30 1:58 ` Nicholas Piggin
2020-06-27 15:04 ` [PATCH 2/3] powerpc/pseries: Use doorbells even if XIVE is available Nicholas Piggin
2020-06-27 15:04 ` [PATCH 3/3] powerpc/pseries: Add KVM guest doorbell restrictions Nicholas Piggin
2020-06-30 2:27 ` Paul Mackerras
2020-06-30 5:35 ` Nicholas Piggin [this message]
2020-06-30 8:26 ` Paul Mackerras
2020-06-30 11:57 ` Nicholas Piggin
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