From: Catalin Marinas <catalin.marinas@arm.com>
To: Marc Zyngier <maz@kernel.org>
Cc: Peter Maydell <peter.maydell@linaro.org>,
Juan Quintela <quintela@redhat.com>,
QEMU Developers <qemu-devel@nongnu.org>,
Dave Martin <Dave.Martin@arm.com>,
Richard Henderson <richard.henderson@linaro.org>,
lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
Steven Price <steven.price@arm.com>,
arm-mail-list <linux-arm-kernel@lists.infradead.org>,
Haibo Xu <haibo.xu@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>,
kvmarm <kvmarm@lists.cs.columbia.edu>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [PATCH v5 0/2] MTE support for KVM guest
Date: Wed, 9 Dec 2020 12:44:43 +0000 [thread overview]
Message-ID: <20201209124443.GB13566@gaia> (raw)
In-Reply-To: <7ff14490e253878d0735633b792e1ea9@kernel.org>
On Tue, Dec 08, 2020 at 06:21:12PM +0000, Marc Zyngier wrote:
> On 2020-12-08 17:21, Catalin Marinas wrote:
> > On Mon, Dec 07, 2020 at 07:03:13PM +0000, Marc Zyngier wrote:
> > > I wonder whether we will have to have something kernel side to
> > > dump/reload tags in a way that matches the patterns used by live
> > > migration.
> >
> > We have something related - ptrace dumps/resores the tags. Can the same
> > concept be expanded to a KVM ioctl?
>
> Yes, although I wonder whether we should integrate this deeply into
> the dirty-log mechanism: it would be really interesting to dump the
> tags at the point where the page is flagged as clean from a dirty-log
> point of view. As the page is dirtied, discard the saved tags.
From the VMM perspective, the tags can be treated just like additional
(meta)data in a page. We'd only need the tags when copying over. It can
race with the VM dirtying the page (writing tags would dirty it) but I
don't think the current migration code cares about this. If dirtied, it
copies it again.
The only downside I see is an extra syscall per page both on the origin
VMM and the destination one to dump/restore the tags. Is this a
performance issue?
--
Catalin
next prev parent reply other threads:[~2020-12-09 12:46 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 15:38 [PATCH v5 0/2] MTE support for KVM guest Steven Price
2020-11-19 15:39 ` [PATCH v5 1/2] arm64: kvm: Save/restore MTE registers Steven Price
2020-11-19 15:39 ` [PATCH v5 2/2] arm64: kvm: Introduce MTE VCPU feature Steven Price
2020-11-19 15:45 ` [PATCH v5 0/2] MTE support for KVM guest Peter Maydell
2020-11-19 15:57 ` Steven Price
2020-11-19 16:39 ` Peter Maydell
2020-11-19 18:42 ` Andrew Jones
2020-11-19 19:11 ` Marc Zyngier
2020-11-20 9:50 ` Steven Price
2020-11-20 9:56 ` Marc Zyngier
2020-11-20 9:58 ` Steven Price
2020-12-04 8:25 ` Haibo Xu
2020-12-07 14:48 ` Steven Price
2020-12-07 15:27 ` Peter Maydell
2020-12-07 15:45 ` Steven Price
2020-12-07 16:05 ` Marc Zyngier
2020-12-07 16:34 ` Catalin Marinas
2020-12-07 19:03 ` Marc Zyngier
2020-12-08 17:21 ` Catalin Marinas
2020-12-08 18:21 ` Marc Zyngier
2020-12-09 12:44 ` Catalin Marinas [this message]
2020-12-09 13:25 ` Marc Zyngier
2020-12-09 15:27 ` Catalin Marinas
2020-12-09 18:27 ` Richard Henderson
2020-12-09 18:39 ` Catalin Marinas
2020-12-09 20:13 ` Richard Henderson
2020-12-09 20:20 ` Peter Maydell
2020-12-07 16:44 ` Dr. David Alan Gilbert
2020-12-07 17:10 ` Peter Maydell
2020-12-07 17:44 ` Dr. David Alan Gilbert
2020-12-08 10:05 ` Haibo Xu
2020-12-08 9:51 ` Haibo Xu
2020-12-08 10:01 ` Marc Zyngier
2020-12-08 10:10 ` Haibo Xu
2020-12-16 7:31 ` Haibo Xu
2020-12-16 10:22 ` Steven Price
2020-12-17 1:47 ` Haibo Xu
2020-11-23 12:16 ` Dr. David Alan Gilbert
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