From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Andrew Jones <drjones@redhat.com>
Cc: Peter Maydell <Peter.Maydell@arm.com>,
linux-kernel@vger.kernel.org, Juan Quintela <quintela@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Richard Henderson <richard.henderson@linaro.org>,
qemu-devel@nongnu.org, Steven Price <steven.price@arm.com>,
Marc Zyngier <maz@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
Dave Martin <Dave.Martin@arm.com>
Subject: Re: [PATCH v2 0/2] MTE support for KVM guest
Date: Thu, 10 Sep 2020 14:27:48 +0100 [thread overview]
Message-ID: <20200910132748.GF2814@work-vm> (raw)
In-Reply-To: <20200910054440.pvnzk7p7riiy45e2@kamzik.brq.redhat.com>
* Andrew Jones (drjones@redhat.com) wrote:
> On Wed, Sep 09, 2020 at 06:45:33PM -0700, Richard Henderson wrote:
> > On 9/9/20 8:25 AM, Andrew Jones wrote:
> > >> * Provide a KVM-specific method to extract the tags from guest memory.
> > >> This might also have benefits in terms of providing an easy way to
> > >> read bulk tag data from guest memory (since the LDGM instruction
> > >> isn't available at EL0).
> > >
> > > Maybe we need a new version of KVM_GET_DIRTY_LOG that also provides
> > > the tags for all addresses of each dirty page.
> >
> > KVM_GET_DIRTY_LOG just provides one bit per dirty page, no? Then VMM copies
> > the data out from its local address to guest memory.
> >
> > There'd be no difference with or without tags, afaik. It's just about how VMM
> > copies the data, with or without tags.
>
> Right, as long as it's fast enough to do
>
> for_each_dirty_page(page, dirty_log)
> for (i = 0; i < host-page-size/16; i += 16)
> append_tag(LDG(page + i))
>
> to get all the tags for each dirty page. I understood it would be faster
> to use LDGM, but we'd need a new ioctl for that. So I was proposing we
> just piggyback on a new dirty-log ioctl instead.
That feels a bad idea to me; there's a couple of different ways dirty
page checking work; lets keep extracting the tags separate.
Dave
> Thanks,
> drew
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
WARNING: multiple messages have this Message-ID (diff)
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Andrew Jones <drjones@redhat.com>
Cc: Peter Maydell <Peter.Maydell@arm.com>,
linux-kernel@vger.kernel.org, Juan Quintela <quintela@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Richard Henderson <richard.henderson@linaro.org>,
qemu-devel@nongnu.org, Steven Price <steven.price@arm.com>,
Marc Zyngier <maz@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
Dave Martin <Dave.Martin@arm.com>
Subject: Re: [PATCH v2 0/2] MTE support for KVM guest
Date: Thu, 10 Sep 2020 14:27:48 +0100 [thread overview]
Message-ID: <20200910132748.GF2814@work-vm> (raw)
In-Reply-To: <20200910054440.pvnzk7p7riiy45e2@kamzik.brq.redhat.com>
* Andrew Jones (drjones@redhat.com) wrote:
> On Wed, Sep 09, 2020 at 06:45:33PM -0700, Richard Henderson wrote:
> > On 9/9/20 8:25 AM, Andrew Jones wrote:
> > >> * Provide a KVM-specific method to extract the tags from guest memory.
> > >> This might also have benefits in terms of providing an easy way to
> > >> read bulk tag data from guest memory (since the LDGM instruction
> > >> isn't available at EL0).
> > >
> > > Maybe we need a new version of KVM_GET_DIRTY_LOG that also provides
> > > the tags for all addresses of each dirty page.
> >
> > KVM_GET_DIRTY_LOG just provides one bit per dirty page, no? Then VMM copies
> > the data out from its local address to guest memory.
> >
> > There'd be no difference with or without tags, afaik. It's just about how VMM
> > copies the data, with or without tags.
>
> Right, as long as it's fast enough to do
>
> for_each_dirty_page(page, dirty_log)
> for (i = 0; i < host-page-size/16; i += 16)
> append_tag(LDG(page + i))
>
> to get all the tags for each dirty page. I understood it would be faster
> to use LDGM, but we'd need a new ioctl for that. So I was proposing we
> just piggyback on a new dirty-log ioctl instead.
That feels a bad idea to me; there's a couple of different ways dirty
page checking work; lets keep extracting the tags separate.
Dave
> Thanks,
> drew
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Andrew Jones <drjones@redhat.com>
Cc: Richard Henderson <richard.henderson@linaro.org>,
Steven Price <steven.price@arm.com>,
Peter Maydell <Peter.Maydell@arm.com>,
Juan Quintela <quintela@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
qemu-devel@nongnu.org, kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
Marc Zyngier <maz@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>, Dave Martin <Dave.Martin@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/2] MTE support for KVM guest
Date: Thu, 10 Sep 2020 14:27:48 +0100 [thread overview]
Message-ID: <20200910132748.GF2814@work-vm> (raw)
In-Reply-To: <20200910054440.pvnzk7p7riiy45e2@kamzik.brq.redhat.com>
* Andrew Jones (drjones@redhat.com) wrote:
> On Wed, Sep 09, 2020 at 06:45:33PM -0700, Richard Henderson wrote:
> > On 9/9/20 8:25 AM, Andrew Jones wrote:
> > >> * Provide a KVM-specific method to extract the tags from guest memory.
> > >> This might also have benefits in terms of providing an easy way to
> > >> read bulk tag data from guest memory (since the LDGM instruction
> > >> isn't available at EL0).
> > >
> > > Maybe we need a new version of KVM_GET_DIRTY_LOG that also provides
> > > the tags for all addresses of each dirty page.
> >
> > KVM_GET_DIRTY_LOG just provides one bit per dirty page, no? Then VMM copies
> > the data out from its local address to guest memory.
> >
> > There'd be no difference with or without tags, afaik. It's just about how VMM
> > copies the data, with or without tags.
>
> Right, as long as it's fast enough to do
>
> for_each_dirty_page(page, dirty_log)
> for (i = 0; i < host-page-size/16; i += 16)
> append_tag(LDG(page + i))
>
> to get all the tags for each dirty page. I understood it would be faster
> to use LDGM, but we'd need a new ioctl for that. So I was proposing we
> just piggyback on a new dirty-log ioctl instead.
That feels a bad idea to me; there's a couple of different ways dirty
page checking work; lets keep extracting the tags separate.
Dave
> Thanks,
> drew
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
WARNING: multiple messages have this Message-ID (diff)
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Andrew Jones <drjones@redhat.com>
Cc: Peter Maydell <Peter.Maydell@arm.com>,
linux-kernel@vger.kernel.org, Juan Quintela <quintela@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Richard Henderson <richard.henderson@linaro.org>,
qemu-devel@nongnu.org, Steven Price <steven.price@arm.com>,
Marc Zyngier <maz@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
Dave Martin <Dave.Martin@arm.com>
Subject: Re: [PATCH v2 0/2] MTE support for KVM guest
Date: Thu, 10 Sep 2020 14:27:48 +0100 [thread overview]
Message-ID: <20200910132748.GF2814@work-vm> (raw)
In-Reply-To: <20200910054440.pvnzk7p7riiy45e2@kamzik.brq.redhat.com>
* Andrew Jones (drjones@redhat.com) wrote:
> On Wed, Sep 09, 2020 at 06:45:33PM -0700, Richard Henderson wrote:
> > On 9/9/20 8:25 AM, Andrew Jones wrote:
> > >> * Provide a KVM-specific method to extract the tags from guest memory.
> > >> This might also have benefits in terms of providing an easy way to
> > >> read bulk tag data from guest memory (since the LDGM instruction
> > >> isn't available at EL0).
> > >
> > > Maybe we need a new version of KVM_GET_DIRTY_LOG that also provides
> > > the tags for all addresses of each dirty page.
> >
> > KVM_GET_DIRTY_LOG just provides one bit per dirty page, no? Then VMM copies
> > the data out from its local address to guest memory.
> >
> > There'd be no difference with or without tags, afaik. It's just about how VMM
> > copies the data, with or without tags.
>
> Right, as long as it's fast enough to do
>
> for_each_dirty_page(page, dirty_log)
> for (i = 0; i < host-page-size/16; i += 16)
> append_tag(LDG(page + i))
>
> to get all the tags for each dirty page. I understood it would be faster
> to use LDGM, but we'd need a new ioctl for that. So I was proposing we
> just piggyback on a new dirty-log ioctl instead.
That feels a bad idea to me; there's a couple of different ways dirty
page checking work; lets keep extracting the tags separate.
Dave
> Thanks,
> drew
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2020-09-10 13:28 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 16:00 [PATCH v2 0/2] MTE support for KVM guest Steven Price
2020-09-04 16:00 ` Steven Price
2020-09-04 16:00 ` Steven Price
2020-09-04 16:00 ` Steven Price
2020-09-04 16:00 ` [PATCH v2 1/2] arm64: kvm: Save/restore MTE registers Steven Price
2020-09-04 16:00 ` Steven Price
2020-09-04 16:00 ` Steven Price
2020-09-04 16:00 ` Steven Price
2020-09-04 16:00 ` [PATCH v2 2/2] arm64: kvm: Introduce MTE VCPU feature Steven Price
2020-09-04 16:00 ` Steven Price
2020-09-04 16:00 ` Steven Price
2020-09-04 16:00 ` Steven Price
2020-09-09 15:48 ` Andrew Jones
2020-09-09 15:48 ` Andrew Jones
2020-09-09 15:48 ` Andrew Jones
2020-09-09 15:48 ` Andrew Jones
2020-09-09 15:53 ` Peter Maydell
2020-09-09 15:53 ` Peter Maydell
2020-09-09 15:53 ` Peter Maydell
2020-09-09 15:53 ` Peter Maydell
2020-09-10 6:38 ` Andrew Jones
2020-09-10 6:38 ` Andrew Jones
2020-09-10 6:38 ` Andrew Jones
2020-09-10 6:38 ` Andrew Jones
2020-09-10 10:01 ` Andrew Jones
2020-09-10 10:01 ` Andrew Jones
2020-09-10 10:01 ` Andrew Jones
2020-09-10 10:01 ` Andrew Jones
2020-09-10 9:21 ` Steven Price
2020-09-10 9:21 ` Steven Price
2020-09-10 9:21 ` Steven Price
2020-09-10 9:21 ` Steven Price
2020-09-10 11:49 ` Andrew Jones
2020-09-10 11:49 ` Andrew Jones
2020-09-10 11:49 ` Andrew Jones
2020-09-10 11:49 ` Andrew Jones
2020-09-07 15:28 ` [PATCH v2 0/2] MTE support for KVM guest Dr. David Alan Gilbert
2020-09-07 15:28 ` Dr. David Alan Gilbert
2020-09-07 15:28 ` Dr. David Alan Gilbert
2020-09-07 15:28 ` Dr. David Alan Gilbert
2020-09-09 9:15 ` Steven Price
2020-09-09 9:15 ` Steven Price
2020-09-09 9:15 ` Steven Price
2020-09-09 9:15 ` Steven Price
2020-09-09 15:25 ` Andrew Jones
2020-09-09 15:25 ` Andrew Jones
2020-09-09 15:25 ` Andrew Jones
2020-09-09 15:25 ` Andrew Jones
2020-09-09 16:04 ` Steven Price
2020-09-09 16:04 ` Steven Price
2020-09-09 16:04 ` Steven Price
2020-09-09 16:04 ` Steven Price
2020-09-10 6:29 ` Andrew Jones
2020-09-10 6:29 ` Andrew Jones
2020-09-10 6:29 ` Andrew Jones
2020-09-10 6:29 ` Andrew Jones
2020-09-10 9:21 ` Steven Price
2020-09-10 9:21 ` Steven Price
2020-09-10 9:21 ` Steven Price
2020-09-10 9:21 ` Steven Price
2020-09-10 13:56 ` Andrew Jones
2020-09-10 13:56 ` Andrew Jones
2020-09-10 13:56 ` Andrew Jones
2020-09-10 13:56 ` Andrew Jones
2020-09-10 14:14 ` Steven Price
2020-09-10 14:14 ` Steven Price
2020-09-10 14:14 ` Steven Price
2020-09-10 14:14 ` Steven Price
2020-09-10 1:45 ` Richard Henderson
2020-09-10 1:45 ` Richard Henderson
2020-09-10 1:45 ` Richard Henderson
2020-09-10 1:45 ` Richard Henderson
2020-09-10 5:44 ` Andrew Jones
2020-09-10 5:44 ` Andrew Jones
2020-09-10 5:44 ` Andrew Jones
2020-09-10 5:44 ` Andrew Jones
2020-09-10 13:27 ` Dr. David Alan Gilbert [this message]
2020-09-10 13:27 ` Dr. David Alan Gilbert
2020-09-10 13:27 ` Dr. David Alan Gilbert
2020-09-10 13:27 ` Dr. David Alan Gilbert
2020-09-10 13:39 ` Andrew Jones
2020-09-10 13:39 ` Andrew Jones
2020-09-10 13:39 ` Andrew Jones
2020-09-10 13:39 ` Andrew Jones
2020-09-10 0:33 ` Richard Henderson
2020-09-10 0:33 ` Richard Henderson
2020-09-10 0:33 ` Richard Henderson
2020-09-10 0:33 ` Richard Henderson
2020-09-10 10:24 ` Steven Price
2020-09-10 10:24 ` Steven Price
2020-09-10 10:24 ` Steven Price
2020-09-10 10:24 ` Steven Price
2020-09-10 15:36 ` Richard Henderson
2020-09-10 15:36 ` Richard Henderson
2020-09-10 15:36 ` Richard Henderson
2020-09-10 15:36 ` Richard Henderson
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