From: Will Deacon <will.deacon@arm.com>
To: John Garry <john.garry@huawei.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Linuxarm <linuxarm@huawei.com>, James Morse <james.morse@arm.com>,
huangdaode <huangdaode@hisilicon.com>,
"Guohanjun \(Hanjun Guo\)" <guohanjun@huawei.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: kpti: Update arm64_kernel_use_ng_mappings() when forced on
Date: Fri, 1 Mar 2019 11:35:12 +0000 [thread overview]
Message-ID: <20190301113512.GA22488@fuggles.cambridge.arm.com> (raw)
In-Reply-To: <835dc899-578c-d914-4ed3-fa8b3b391ae6@huawei.com>
On Fri, Mar 01, 2019 at 11:18:21AM +0000, John Garry wrote:
> On 16/01/2019 09:38, John Garry wrote:
> > On 15/01/2019 18:49, James Morse wrote:
> > > Since commit b89d82ef01b3 ("arm64: kpti: Avoid rewriting early page
> >
> > About b89d82ef01b3, I got an *unconfirmed* (emphasis on this, I don't
> > want to cry wolf) report yesterday that the symptom I saw (boot delay)
> > has been seen on 5.0-rc2 on our D06 board. I could not see it.
> >
> > Please note that this would be same board which we saw this on:
> > https://lkml.org/lkml/2018/6/20/589
> >
> > I only witnessed the issue on the predecessor A72-based D05 board.
> >
> > The reporter is very busy, but we'll keep tabs on it.
> >
>
> FYI, this just came in this morning:
This isn't completely surprising, because the kernel doesn't know about
the CPU in D06:
> [ 0.000000] Booting Linux on physical CPU 0x0000010000 [0x480fd010]
[...]
> [ 0.000000] CPU features: detected: Kernel page table isolation (KPTI)
If the CPU is not affected by meltdown, you can add the MIDR above to the
kpti_safe_list[] table. If it *is* affected by meltdown, then I'm afraid
that you're stuck with the delay at boot for !KASLR kernels (which is an
awful lot better than getting pwned by userspace :)
I think D06 is 8.2, so I would've hoped that you'd implemented
AA64PFR0_EL1.CSV3, which would make this MIDR-based whitelisting
unnecessary.
Will
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next prev parent reply other threads:[~2019-03-01 11:35 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-15 18:49 [PATCH] arm64: kpti: Update arm64_kernel_use_ng_mappings() when forced on James Morse
2019-01-16 9:38 ` John Garry
2019-01-16 10:33 ` James Morse
[not found] ` <835dc899-578c-d914-4ed3-fa8b3b391ae6@huawei.com>
2019-03-01 11:35 ` Will Deacon [this message]
2019-03-01 11:43 ` Ard Biesheuvel
2019-03-01 11:45 ` Will Deacon
2019-03-01 11:46 ` Ard Biesheuvel
2019-03-01 12:59 ` Hanjun Guo
2019-03-01 13:02 ` Will Deacon
2019-03-01 13:34 ` Hanjun Guo
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