From: catalin.marinas@arm•com (Catalin Marinas)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v4 4/7] arm64: Handle early CPU boot failures
Date: Wed, 3 Feb 2016 17:15:42 +0000 [thread overview]
Message-ID: <20160203171541.GC26487@MBP.local> (raw)
In-Reply-To: <20160203170114.GD1234@leverpostej>
On Wed, Feb 03, 2016 at 05:01:15PM +0000, Mark Rutland wrote:
> On Mon, Jan 25, 2016 at 06:07:02PM +0000, Suzuki K Poulose wrote:
> > From: Suzuki K. Poulose <suzuki.poulose@arm•com>
> >
> > A secondary CPU could fail to come online due to insufficient
> > capabilities and could simply die or loop in the kernel.
> > e.g, a CPU with no support for the selected kernel PAGE_SIZE
> > loops in kernel with MMU turned off.
> > or a hotplugged CPU which doesn't have one of the advertised
> > system capability will die during the activation.
> >
> > There is no way to synchronise the status of the failing CPU
> > back to the master. This patch solves the issue by adding a
> > field to the secondary_data which can be updated by the failing
> > CPU. If the secondary CPU fails even before turning the MMU on,
> > it updates the status in a special variable reserved in the head.txt
> > section to make sure that the update can be cache invalidated safely
> > without possible sharing of cache write back granule.
> >
> > Here are the possible states :
> >
> > -1. CPU_MMU_OFF - Initial value set by the master CPU, this value
> > indicates that the CPU could not turn the MMU on, hence the status
> > could not be reliably updated in the secondary_data. Instead, the
> > CPU has updated the status in __early_cpu_boot_status (reserved in
> > head.txt section)
> >
> > 0. CPU_BOOT_SUCCESS - CPU has booted successfully.
> >
> > 1. CPU_KILL_ME - CPU has invoked cpu_ops->die, indicating the
> > master CPU to synchronise by issuing a cpu_ops->cpu_kill.
> >
> > 2. CPU_STUCK_IN_KERNEL - CPU couldn't invoke die(), instead is
> > looping in the kernel. This information could be used by say,
> > kexec to check if it is really safe to do a kexec reboot.
> >
> > 3. CPU_PANIC_KERNEL - CPU detected some serious issues which
> > requires kernel to crash immediately. The secondary CPU cannot
> > call panic() until it has initialised the GIC. This flag can
> > be used to instruct the master to do so.
>
> When would we use this last case?
It's used in a subsequent series when verifying the ASID bits. I haven't
followed the previous discussions but I guess Suzuki aims to panic the
whole kernel rather than just stop the current CPU when incompatible
ASID size is found.
--
Catalin
next prev parent reply other threads:[~2016-02-03 17:15 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-25 18:06 [PATCH v4 0/7] arm64: Verify early CPU features Suzuki K Poulose
2016-01-25 18:06 ` [PATCH v4 1/7] arm64: Add a helper for parking CPUs in a loop Suzuki K Poulose
2016-01-25 18:07 ` [PATCH v4 2/7] arm64: Introduce cpu_die_early Suzuki K Poulose
2016-01-25 18:07 ` [PATCH v4 3/7] arm64: Move cpu_die_early to smp.c Suzuki K Poulose
2016-01-25 18:07 ` [PATCH v4 4/7] arm64: Handle early CPU boot failures Suzuki K Poulose
2016-02-03 12:57 ` Catalin Marinas
2016-02-03 16:46 ` Mark Rutland
2016-02-03 17:34 ` Catalin Marinas
2016-02-03 17:53 ` Mark Rutland
2016-02-03 18:12 ` Catalin Marinas
2016-02-03 19:31 ` Mark Rutland
2016-02-03 17:23 ` Suzuki K. Poulose
2016-02-03 17:01 ` Mark Rutland
2016-02-03 17:15 ` Catalin Marinas [this message]
2016-02-03 17:24 ` Suzuki K. Poulose
2016-02-03 17:35 ` Mark Rutland
2016-01-25 18:07 ` [PATCH v4 5/7] arm64: Enable CPU capability verification unconditionally Suzuki K Poulose
2016-01-25 18:07 ` [PATCH v4 6/7] arm64: Add helper for extracting ASIDBits Suzuki K Poulose
2016-01-25 18:07 ` [PATCH v4 7/7] arm64: Ensure the secondary CPUs have safe ASIDBits size Suzuki K Poulose
2016-02-09 17:20 ` [PATCH v4 0/7] arm64: Verify early CPU features Will Deacon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160203171541.GC26487@MBP.local \
--to=catalin.marinas@arm$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox