From: Scott Wood <scottwood@freescale.com>
To: Alexander Graf <agraf@suse.de>
Cc: Liu Yu <yu.liu@freescale.com>,
kvm-ppc@vger.kernel.org, kvm@vger.kernel.org,
galak@kernel.crashing.org, timur@freescale.com,
Stuart Yoder <stuart.yoder@freescale.com>
Subject: Re: [PATCH v2 2/3] KVM: PPC: epapr: Add idle hcall support for host
Date: Mon, 09 Jan 2012 20:00:36 +0000 [thread overview]
Message-ID: <4F0B4764.6070801@freescale.com> (raw)
In-Reply-To: <9974D2A0-C91D-442E-8972-529E24418A28@suse.de>
On 01/09/2012 08:15 AM, Alexander Graf wrote:
>
> On 05.01.2012, at 10:07, Liu Yu wrote:
>
>> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
>> index c33f6a7..1242ee1 100644
>> --- a/arch/powerpc/kvm/powerpc.c
>> +++ b/arch/powerpc/kvm/powerpc.c
>> @@ -81,6 +81,10 @@ int kvmppc_kvm_pv(struct kvm_vcpu *vcpu)
>>
>> /* Second return value is in r4 */
>> break;
>> + case HC_VENDOR_EPAPR | HC_EV_IDLE:
>> + r = HC_EV_SUCCESS;
>> + kvm_vcpu_block(vcpu);
>
> Hrm. This will return on signal. So if the guest sends an idle hcall,
> then user space gets a random signal, we'll continue executing the
> guest CPU, getting us out of idle even though the guest didn't expect
> it, since the guest really wants to get an interrupt after the idle
> hcall.
The ePAPR description of this hcall is a little vague (Stuart, put on
list to fix in next ePAPR revision?), but this is expected. It will
also be the case if a guest directly uses the wait instruction. Guests
must be able to deal with spurious wakeups.
-Scott
next prev parent reply other threads:[~2012-01-09 20:00 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-05 9:07 [PATCH v2 2/3] KVM: PPC: epapr: Add idle hcall support for host Liu Yu
2012-01-09 14:15 ` Alexander Graf
2012-01-09 16:04 ` Yoder Stuart-B08248
2012-01-09 16:07 ` Alexander Graf
2012-01-09 22:41 ` Yoder Stuart-B08248
2012-01-09 22:51 ` Alexander Graf
2012-01-09 20:00 ` Scott Wood [this message]
2012-01-09 20:18 ` Alexander Graf
2012-01-09 22:33 ` Scott Wood
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4F0B4764.6070801@freescale.com \
--to=scottwood@freescale.com \
--cc=agraf@suse.de \
--cc=galak@kernel.crashing.org \
--cc=kvm-ppc@vger.kernel.org \
--cc=kvm@vger.kernel.org \
--cc=stuart.yoder@freescale.com \
--cc=timur@freescale.com \
--cc=yu.liu@freescale.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox