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From: Greg KH <gregkh@linuxfoundation.org>
To: Will Deacon <will@kernel.org>
Cc: Mark Brown <broonie@kernel.org>, Sasha Levin <sashal@kernel.org>,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org,
	Kristina Martsenko <kristina.martsenko@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	james.morse@arm.com, mark.rutland@arm.com, amit.kachhap@arm.com,
	maz@kernel.org, anshuman.khandual@arm.com, joey.gouly@arm.com,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH AUTOSEL 6.4 07/12] arm64: cpufeature: detect FEAT_HCX
Date: Mon, 10 Jul 2023 15:31:42 +0200	[thread overview]
Message-ID: <2023071024-unpaved-washed-4d7d@gregkh> (raw)
In-Reply-To: <20230710094438.GD32673@willie-the-truck>

On Mon, Jul 10, 2023 at 10:44:38AM +0100, Will Deacon wrote:
> On Sun, Jul 09, 2023 at 10:13:29PM +0100, Mark Brown wrote:
> > On Sun, Jul 09, 2023 at 10:56:13AM -0400, Sasha Levin wrote:
> > > On Mon, Jul 03, 2023 at 12:51:57PM +0100, Mark Brown wrote:
> > > > On Sun, Jul 02, 2023 at 03:50:52PM -0400, Sasha Levin wrote:
> > 
> > > > > KVM currently relies on the register being present on all CPUs (or
> > > > > none), so the kernel will panic if that is not the case. Fortunately no
> > > > > such systems currently exist, but this can be revisited if they appear.
> > > > > Note that the kernel will not panic if CONFIG_KVM is disabled.
> > 
> > > > This is a new feature, it's not clear why we'd backport it (especially
> > > > since it's a new feature which is a dependency for other features rather
> > > > than something that people can use outside of the kernel)?
> > 
> > > The second paragraph (above) suggested it should be.
> > 
> > That's saying that the code won't work properly on systems where some
> > but not all of the CPUs support the feature.  Note that the changelog
> > says nothing about fixing any issue here.
> 
> Try reading it like a GPU running an ML model:
> 
>   "This is not a new feature, it's especially clear why we'd backport it."
> 
> Makes sense. *sigh*
> 
> We've been considering opting arm64 out of this for a while, but I don't
> think we do a great job of CC'ing stable either (I certainly forget to
> add it all the time and then hope that the Fixes: tag does the job),so
> it's not obviously going to improve things.
> 
> Maybe we just need a commit hook that yells if something with a Fixes:
> tag doesn't have a CC: stable on it?

I could start doing that, it's going to be really noisy...

greg k-h

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  reply	other threads:[~2023-07-10 13:32 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20230702195057.1787686-1-sashal@kernel.org>
2023-07-02 19:50 ` [PATCH AUTOSEL 6.4 07/12] arm64: cpufeature: detect FEAT_HCX Sasha Levin
2023-07-03 11:51   ` Mark Brown
2023-07-09 14:56     ` Sasha Levin
2023-07-09 21:13       ` Mark Brown
2023-07-10  9:44         ` Will Deacon
2023-07-10 13:31           ` Greg KH [this message]
2023-07-10 13:47             ` Mark Brown
2023-07-10 14:09               ` Greg KH
2023-07-02 19:50 ` [PATCH AUTOSEL 6.4 09/12] arm64: set __exception_irq_entry with __irq_entry as a default Sasha Levin
2023-07-02 19:50 ` [PATCH AUTOSEL 6.4 10/12] arm64: mm: fix VA-range sanity check Sasha Levin
2023-07-02 19:50 ` [PATCH AUTOSEL 6.4 11/12] drivers/perf: hisi: Add support for HiSilicon H60PA and PAv3 PMU driver Sasha Levin
2023-07-03 10:14   ` Mark Rutland
2023-07-21 15:13     ` Sasha Levin

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