linux-kernel - Re: [PATCH v2] arm64: invalidate TLB just before turning MMU on

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Message-ID: <CAKv+Gu80cxx6L3KYyYnsyjbrWN6iTp76jcdBio27b_h+dAzaHw@mail.gmail.com>
Date:   Fri, 14 Dec 2018 08:23:54 +0100
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Qian Cai <cai@....pw>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        James Morse <james.morse@....com>,
        AKASHI Takahiro <takahiro.akashi@...aro.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Kexec Mailing List <kexec@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] arm64: invalidate TLB just before turning MMU on

On Fri, 14 Dec 2018 at 05:08, Qian Cai <cai@....pw> wrote:
> Also tried to move the local TLB flush part around a bit inside
> __cpu_setup(), although it did complete kdump some times, it did trigger
> "Synchronous Exception" in EFI after a cold-reboot fairly often that
> seems no way to recover remotely without reinstalling the OS.

This doesn't make any sense to me. If the system gets into a weird
state out of cold reboot, how could this code be the culprit? Please
check your firmware, and try to reproduce the issue on a system that
doesn't have such defects.