From: Tom Rini <trini@konsulko.com>
To: Marc Zyngier <maz@kernel.org>,
"Ying-Chun Liu (PaulLiu)" <paul.liu@linaro.org>
Cc: u-boot@lists.denx.de, Will Deacon <willdeacon@google.com>
Subject: Re: [PATCH 1/2] arm: cpu: Add optional CMOs by VA
Date: Tue, 7 Feb 2023 11:40:05 -0500 [thread overview]
Message-ID: <Y+J+5eVwTS8cygn6@bill-the-cat> (raw)
In-Reply-To: <0acfdc333e22249784b4abd63d8d09e6@kernel.org>
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On Tue, Feb 07, 2023 at 04:35:25PM +0000, Marc Zyngier wrote:
> On 2023-02-07 16:20, Ying-Chun Liu (PaulLiu) wrote:
> > Exposing set/way cache maintenance to a virtual machine is unsafe, not
> > least because the instructions are not permission-checked but also
> > because they are not broadcast between CPUs. Consequently, KVM traps and
> > emulates such maintenance in the host kernel using by-VA operations and
> > looping over the stage-2 page-tables. However, when running under
> > protected KVM, these instructions are not able to be emulated and will
> > instead result in an exception being delivered to the guest.
> >
> > Introduce CONFIG_CMO_BY_VA_ONLY so that virtual platforms can select
> > this option and perform by-VA cache maintenance instead of using the
> > set/way instructions.
> >
> > Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
> > Signed-off-by: Marc Zyngier <maz@kernel.org>
> > Signed-off-by: Will Deacon <willdeacon@google.com>
> > Cc: Tom Rini <trini@konsulko.com>
>
> The sign-off chain looks pretty odd. Either you are the author
> of this patch, and I have nothing to do on the sign-off list,
> or I'm the author and the authorship is wrong. Similar things
> would apply for Will.
>
> So which one is it?
As my first guess here is copy and adopting code from Linux, this is
not following the documented procedure here:
https://u-boot.readthedocs.io/en/latest/develop/sending_patches.html#attributing-code-copyrights-signing
Which if not sufficiently clear, please ask / suggest changes to. I see
right now it isn't specific about cc'ing the original authors (who may,
or may not, be interested, so blanket policy doesn't apply) but I would
hope is clear enough that what's done in this example isn't right.
--
Tom
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next prev parent reply other threads:[~2023-02-07 16:40 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-07 16:20 [PATCH 0/2] arm: cpu: Add optional CMOs by VA Ying-Chun Liu (PaulLiu)
2023-02-07 16:20 ` [PATCH 1/2] " Ying-Chun Liu (PaulLiu)
2023-02-07 16:35 ` Marc Zyngier
2023-02-07 16:40 ` Tom Rini [this message]
2023-02-07 17:06 ` Marc Zyngier
2023-02-07 17:12 ` Tom Rini
2023-02-07 17:18 ` Paul Liu
2023-02-08 8:20 ` Marc Zyngier
2023-02-07 16:20 ` [PATCH 2/2] arm64: Initialize TLB memory if CMO_BY_VA_ONLY Ying-Chun Liu (PaulLiu)
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