From: Peter Zijlstra <peterz@infradead.org>
To: Wanpeng Li <kernellwp@gmail.com>
Cc: linux-s390 <linux-s390@vger.kernel.org>,
Davidlohr Bueso <dave@stgolabs.net>,
benh@kernel.crashing.org, kvm <kvm@vger.kernel.org>,
mpe@ellerman.id.au, boqun.feng@gmail.com, will.deacon@arm.com,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Waiman Long <waiman.long@hpe.com>,
virtualization@lists.linux-foundation.org,
Ingo Molnar <mingo@redhat.com>, Paul Mackerras <paulus@samba.org>,
Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>,
schwidefsky@de.ibm.com, Paolo Bonzini <pbonzini@redhat.com>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2 0/4] implement vcpu preempted check
Date: Thu, 7 Jul 2016 13:15:54 +0200 [thread overview]
Message-ID: <20160707111554.GV30921@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CANRm+CxKVqrFB-cRPEvmUamZ5Y8cOGe3pyc0LMJy0t9_jo+i0Q@mail.gmail.com>
On Thu, Jul 07, 2016 at 06:27:26PM +0800, Wanpeng Li wrote:
> In addition, I see xen's vcpu_runstate_info::state is updated during
> schedule, so I think I can do this similarly through kvm preemption
> notifier. IIUC, xen hypervisor has VCPUOP_get_runstate_info hypercall
> implemention, so the desired interface can be implemented if they add
> hypercall callsite in domU. I can add hypercall to kvm similarly.
So I suspect Xen has the page its writing to pinned in memory; so that a
write to it is guaranteed to not fault.
Otherwise I cannot see this working.
That is part of the larger surgery required for KVM steal time to get
'fixed'. Currently that steal time stuff uses kvm_write_guest_cached()
which appears to be able to fault in guest pages.
Or I'm not reading this stuff right; which is entirely possible.
next prev parent reply other threads:[~2016-07-07 11:15 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1467124991-13164-1-git-send-email-xinhui.pan@linux.vnet.ibm.com>
[not found] ` <1467124991-13164-3-git-send-email-xinhui.pan@linux.vnet.ibm.com>
[not found] ` <CANRm+CxQMSrg69p2Xey829Mz4Au9YCai+4JD17i9urdbj0VgkQ@mail.gmail.com>
[not found] ` <577C8FE3.3010208@linux.vnet.ibm.com>
2016-07-06 6:46 ` [PATCH v2 2/4] powerpc/spinlock: support vcpu preempted check Wanpeng Li
2016-07-06 7:58 ` Peter Zijlstra
2016-07-06 8:32 ` Wanpeng Li
2016-07-06 10:18 ` xinhui
[not found] ` <20160706065255.GH30909@twins.programming.kicks-ass.net>
[not found] ` <14a24854-9787-e4a1-c9a8-76eba4e97301@redhat.com>
2016-07-06 12:08 ` [PATCH v2 0/4] implement " Wanpeng Li
2016-07-06 12:28 ` Paolo Bonzini
2016-07-06 13:03 ` Wanpeng Li
2016-07-07 8:48 ` Wanpeng Li
2016-07-07 9:42 ` Peter Zijlstra
2016-07-07 10:12 ` Wanpeng Li
2016-07-07 10:27 ` Wanpeng Li
2016-07-07 11:15 ` Peter Zijlstra [this message]
2016-07-07 11:08 ` Peter Zijlstra
2016-07-07 11:09 ` Peter Zijlstra
2016-07-07 11:21 ` Peter Zijlstra
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