From: "Michael S. Tsirkin" <mst@redhat.com>
To: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, rkrcmar@redhat.com, x86@kernel.org,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
pbonzini@redhat.com, tglx@linutronix.de,
akpm@linux-foundation.org
Subject: Re: [RFC PATCH 2/4] kvm: Add host side support for free memory hints
Date: Mon, 11 Feb 2019 12:36:55 -0500 [thread overview]
Message-ID: <20190211123638-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <96285ed154dbb92686ca0068e21f5e0500bb1ce7.camel@linux.intel.com>
On Mon, Feb 11, 2019 at 09:34:25AM -0800, Alexander Duyck wrote:
> On Sat, 2019-02-09 at 19:44 -0500, Michael S. Tsirkin wrote:
> > On Mon, Feb 04, 2019 at 10:15:46AM -0800, Alexander Duyck wrote:
> > > From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> > >
> > > Add the host side of the KVM memory hinting support. With this we expose a
> > > feature bit indicating that the host will pass the messages along to the
> > > new madvise function.
> > >
> > > This functionality is mutually exclusive with device assignment. If a
> > > device is assigned we will disable the functionality as it could lead to a
> > > potential memory corruption if a device writes to a page after KVM has
> > > flagged it as not being used.
> >
> > I really dislike this kind of tie-in.
> >
> > Yes right now assignment is not smart enough but generally
> > you can protect the unused page in the IOMMU and that's it,
> > it's safe.
> >
> > So the policy should not leak into host/guest interface.
> > Instead it is better to just keep the pages pinned and
> > ignore the hint for now.
>
> Okay, I can do that. It also gives me a means of benchmarking just the
> hypercall cost versus the extra page faults and zeroing.
Good point. Same goes for poisoning :)
next prev parent reply other threads:[~2019-02-11 17:37 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-04 18:15 [RFC PATCH 0/4] kvm: Report unused guest pages to host Alexander Duyck
2019-02-04 18:15 ` [RFC PATCH 1/4] madvise: Expose ability to set dontneed from kernel Alexander Duyck
2019-02-04 18:15 ` [RFC PATCH 2/4] kvm: Add host side support for free memory hints Alexander Duyck
2019-02-10 0:44 ` Michael S. Tsirkin
2019-02-11 17:34 ` Alexander Duyck
2019-02-11 17:34 ` Alexander Duyck
2019-02-11 17:36 ` Michael S. Tsirkin [this message]
2019-02-11 17:41 ` Dave Hansen
2019-02-11 17:48 ` Michael S. Tsirkin
2019-02-11 18:30 ` Alexander Duyck
2019-02-11 18:30 ` Alexander Duyck
2019-02-11 19:24 ` Michael S. Tsirkin
2019-02-04 18:15 ` [RFC PATCH 3/4] kvm: Add guest " Alexander Duyck
2019-02-04 19:44 ` Dave Hansen
2019-02-04 20:42 ` Alexander Duyck
2019-02-04 20:42 ` Alexander Duyck
2019-02-04 23:00 ` Nadav Amit
2019-02-04 23:37 ` Alexander Duyck
2019-02-04 23:37 ` Alexander Duyck
2019-02-05 0:03 ` Nadav Amit
2019-02-05 0:16 ` Alexander Duyck
2019-02-05 0:16 ` Alexander Duyck
2019-02-05 1:46 ` Nadav Amit
2019-02-05 18:09 ` Alexander Duyck
2019-02-05 18:09 ` Alexander Duyck
2019-02-07 18:21 ` Luiz Capitulino
2019-02-07 18:44 ` Alexander Duyck
2019-02-07 18:44 ` Alexander Duyck
2019-02-07 20:02 ` Luiz Capitulino
2019-02-07 20:02 ` Luiz Capitulino
2019-02-08 21:05 ` Nitesh Narayan Lal
2019-02-08 21:31 ` Alexander Duyck
2019-02-08 21:31 ` Alexander Duyck
2019-02-10 0:49 ` Michael S. Tsirkin
2019-02-11 16:31 ` Alexander Duyck
2019-02-11 16:31 ` Alexander Duyck
2019-02-11 17:36 ` Michael S. Tsirkin
2019-02-11 18:10 ` Alexander Duyck
2019-02-11 18:10 ` Alexander Duyck
2019-02-11 19:54 ` Michael S. Tsirkin
2019-02-11 21:00 ` Alexander Duyck
2019-02-11 21:00 ` Alexander Duyck
2019-02-11 22:52 ` Michael S. Tsirkin
2019-02-12 0:09 ` Alexander Duyck
2019-02-12 0:34 ` Michael S. Tsirkin
2019-02-11 17:48 ` Dave Hansen
2019-02-11 17:58 ` Michael S. Tsirkin
2019-02-11 18:19 ` Dave Hansen
2019-02-11 19:56 ` Michael S. Tsirkin
2019-02-04 18:15 ` [RFC PATCH 4/4] mm: Add merge page notifier Alexander Duyck
2019-02-04 19:40 ` Dave Hansen
2019-02-04 19:51 ` Alexander Duyck
2019-02-04 19:51 ` Alexander Duyck
2019-02-10 0:57 ` Michael S. Tsirkin
2019-02-11 13:30 ` Nitesh Narayan Lal
2019-02-11 14:17 ` Michael S. Tsirkin
2019-02-11 16:24 ` Nitesh Narayan Lal
2019-02-11 17:41 ` Michael S. Tsirkin
2019-02-11 18:09 ` Nitesh Narayan Lal
2019-02-11 6:40 ` Aaron Lu
2019-02-11 15:58 ` Alexander Duyck
2019-02-11 15:58 ` Alexander Duyck
2019-02-12 2:09 ` Aaron Lu
2019-02-12 17:20 ` Alexander Duyck
2019-02-12 17:20 ` Alexander Duyck
2019-02-04 18:19 ` [RFC PATCH QEMU] i386/kvm: Enable paravirtual unused page hint mechanism Alexander Duyck
2019-02-05 17:25 ` [RFC PATCH 0/4] kvm: Report unused guest pages to host Nitesh Narayan Lal
2019-02-05 18:43 ` Alexander Duyck
2019-02-05 18:43 ` Alexander Duyck
2019-02-07 14:48 ` Nitesh Narayan Lal
2019-02-07 16:56 ` Alexander Duyck
2019-02-07 16:56 ` Alexander Duyck
2019-02-10 0:51 ` Michael S. Tsirkin
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