From: Marc Zyngier <marc.zyngier@arm.com>
To: Richard Ruigrok <rruigrok@codeaurora.org>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Cc: Jeffrey Hugo <jhugo@codeaurora.org>,
Thomas Gleixner <tglx@linutronix.de>,
Jason Cooper <jason@lakedaemon.net>,
Jeremy Linton <jeremy.linton@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: Re: [PATCH 00/10] GICv3 support for kexec/kdump on EFI systems
Date: Fri, 28 Sep 2018 11:33:48 +0100 [thread overview]
Message-ID: <911a666a-9f11-5c23-77a4-658afba02644@arm.com> (raw)
In-Reply-To: <44ac1fad-8df4-4738-0f25-8a7a2de8f6df@codeaurora.org>
Hi Richard,
On 27/09/18 22:10, Richard Ruigrok wrote:
> Hi Marc
>
> On 9/21/2018 1:59 PM, Marc Zyngier wrote:
>> The GICv3 architecture has the remarkable feature that once LPI tables
>> have been assigned to redistributors and that LPI delivery is enabled,
>> there is no guarantee that LPIs can be turned off (and most
>> implementations do not allow it), nor can it be reprogrammed to use
>> other tables.
>>
>> This is a bit of a problem for kexec, where the secondary kernel
>> completely looses track of the previous allocations. If the secondary
>> kernel doesn't allocate the tables exactly the same way, no LPIs will
>> be delivered by the GIC (which continues to use the old tables), and
>> memory previously allocated for the pending tables will be slowly
>> corrupted, one bit at a time.
>>
>> The workaround for this is based on a series[1] by Ard Biesheuvel,
>> which adds the required infrastructure for memory reservations to be
>> passed from one kernel to another using an EFI table.
>>
>> This infrastructure is then used to register the allocation of GIC
>> tables with EFI, and allow the GIC driver to safely reuse the existing
>> programming if it detects that the tables have been correctly
>> registered. On non-EFI systems, there is not much we can do.
>>
>> This has been tested on a TX2 system both as a host and a guest. I'd
>> welcome additional testing of different HW. For convenience, I've
>> stashed a branch containing the whole thing at [2].
> I tested [2] from the 4.19-rc4 set which included this series and [1].
> Tested kexec on Centriq system with ITS support (46 core). On-board was a MLX CX5 NIC, verified MSIs are active in /proc/interrupts.
> Prior to this we used a workaround from Shanker to reuse the same tables in the kexec'ed kernel.
Yes, I remember seeing this workaround. Hopefully we're in a better
place now that we can guarantee that the tables are not reused.
> Let me know if further testing is needed, and thanks for adding this support.
Good to know, thanks for having tested it. I've now put this code into
-next for some more soaking. Hopefully nothing horrible will happen ;-)
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2018-09-28 10:33 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-21 19:59 [PATCH 00/10] GICv3 support for kexec/kdump on EFI systems Marc Zyngier
2018-09-21 19:59 ` [PATCH 01/10] irqchip/gic-v3-its: Change initialization ordering for LPIs Marc Zyngier
2018-09-24 10:49 ` Julien Thierry
2018-09-21 19:59 ` [PATCH 02/10] irqchip/gic-v3-its: Consolidate LPI_PENDBASE_SZ usage Marc Zyngier
2018-09-24 10:33 ` Suzuki K Poulose
2018-09-24 10:50 ` Julien Thierry
2018-09-24 10:54 ` Suzuki K Poulose
2018-09-24 10:55 ` Julien Thierry
2018-09-26 10:28 ` Marc Zyngier
2018-09-21 19:59 ` [PATCH 03/10] irqchip/gic-v3-its: Split property table clearing from allocation Marc Zyngier
2018-09-21 19:59 ` [PATCH 04/10] irqchip/gic-v3-its: Move pending table allocation to init time Marc Zyngier
2018-09-24 11:58 ` Julien Thierry
2018-09-26 10:39 ` Marc Zyngier
2018-09-21 19:59 ` [PATCH 05/10] irqchip/gic-v3-its: Keep track of property table's PA and VA Marc Zyngier
2018-09-21 19:59 ` [PATCH 06/10] irqchip/gic-v3-its: Allow use of pre-programmed LPI tables Marc Zyngier
2018-09-24 12:52 ` Julien Thierry
2018-09-21 19:59 ` [PATCH 07/10] irqchip/gic-v3-its: Use pre-programmed redistributor tables with kdump kernels Marc Zyngier
2018-09-21 19:59 ` [PATCH 08/10] irqchip/gic-v3-its: Check that all RDs have the same property table Marc Zyngier
2018-09-21 19:59 ` [PATCH 09/10] irqchip/gic-v3-its: Register LPI tables with EFI config table Marc Zyngier
2018-09-21 19:59 ` [PATCH 10/10] irqchip/gic-v3-its: Allow use of LPI tables in reserved memory Marc Zyngier
2018-09-25 18:48 ` [PATCH 00/10] GICv3 support for kexec/kdump on EFI systems Jeremy Linton
2018-09-27 9:55 ` Bhupesh Sharma
2018-09-27 13:01 ` Zhang, Lei
2018-09-27 21:10 ` Richard Ruigrok
2018-09-28 10:33 ` Marc Zyngier [this message]
[not found] ` <CACiNFG5r2Czfy_kXA2PPQa=xdyzq0vUgoQZ=XNME4d_h=O1oBw@mail.gmail.com>
2019-02-01 9:15 ` Marc Zyngier
2019-02-02 3:05 ` Xulin Sun
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