From: Marc Zyngier <maz@kernel.org>
To: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
Hector Martin <marcan@marcan.st>, Arnd Bergmann <arnd@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
kernel-team@android.com
Subject: Re: [PATCH v2 3/3] arm64: Allow nVHE impaired CPUs to boot without CONFIG_ARM64_VHE
Date: Thu, 08 Apr 2021 11:31:42 +0100 [thread overview]
Message-ID: <8474e539259346842178f51a26d59d74@kernel.org> (raw)
In-Reply-To: <20210407211848.GE16198@willie-the-truck>
On 2021-04-07 22:18, Will Deacon wrote:
> On Tue, Mar 30, 2021 at 06:39:47PM +0100, Marc Zyngier wrote:
>> CPUs stuck in VHE mode need some additional care if the kernel
>> is compiled without CONFIG_ARM64_VHE.
>>
>> Treat this case as another version of a mismatched boot, and
>> prevent KVM from being initialised. The machine will boot in
>> some bizarre state, using TPIDR_EL1 instead of TPIDR_EL2, but
>> otherwise be functional.
>>
>> Signed-off-by: Marc Zyngier <maz@kernel.org>
>> ---
>> arch/arm64/include/asm/virt.h | 18 +++++++++++++-----
>> arch/arm64/kvm/va_layout.c | 9 +++++++++
>> 2 files changed, 22 insertions(+), 5 deletions(-)
>
> Hmm, I think we definitely need _something_ here, but it's a bit
> annoying
> to put ourselves into this weird state just for the sake of one stupid
> machine.
Which is why I'm not keen at all on this patch, and I'm happy to see
the machine die a painful death. We really can't be blamed for
terminally
buggy HW, which the M1 obviously is.
> What if we dropped CONFIG_ARM64_VHE and made the VHE code unconditional
> instead? Is there a good reason to allow it to be disabled nowadays?
What do we do for the other camp, aka people really wanting to run nVHE
without any command line parameter? I can't see why you'd want to do
that, but hey, that's only me.
I'd be quite happy to see CONFIG_ARM64_VHE go though. Let me know if you
want a patch doing that instead.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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next prev parent reply other threads:[~2021-04-08 10:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-30 17:39 [PATCH v2 0/3] arm64: Dealing with VHE-only CPUs Marc Zyngier
2021-03-30 17:39 ` [PATCH v2 1/3] arm64: cpufeature: Allow early filtering of feature override Marc Zyngier
2021-04-08 11:13 ` Hector Martin
2021-04-08 13:11 ` Marc Zyngier
2021-03-30 17:39 ` [PATCH v2 2/3] arm64: Cope with CPUs stuck in VHE mode Marc Zyngier
2021-04-07 21:16 ` Will Deacon
2021-03-30 17:39 ` [PATCH v2 3/3] arm64: Allow nVHE impaired CPUs to boot without CONFIG_ARM64_VHE Marc Zyngier
2021-04-07 21:18 ` Will Deacon
2021-04-08 10:31 ` Marc Zyngier [this message]
2021-04-08 10:58 ` Will Deacon
2021-04-08 13:05 ` Marc Zyngier
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