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From:   Matthew Garrett <mjg59@google.com>
Date:   Mon, 5 Aug 2019 10:09:43 -0700
Message-ID: <CACdnJusRUnhmOLdowqbGoM9Z-tWsKrhZ8sFfQUUmjyKmRVN+vw@mail.gmail.com>
Subject: Re: [PATCH] do not clean dummy variable in kexec path
To:     Dave Young <dyoung@redhat.com>
Cc:     linux-efi <linux-efi@vger.kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        kexec@lists.infradead.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        bhsharma@redhat.com
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On Mon, Aug 5, 2019 at 1:36 AM Dave Young <dyoung@redhat.com> wrote:
>
> kexec reboot fails randomly in UEFI based kvm guest.  The firmware
> just reset while calling efi_delete_dummy_variable();  Unfortunately
> I don't know how to debug the firmware, it is also possible a potential
> problem on real hardware as well although nobody reproduced it.
>
> The intention of efi_delete_dummy_variable is to trigger garbage collection
> when entering virtual mode.  But SetVirtualAddressMap can only run once
> for each physical reboot, thus kexec_enter_virtual_mode is not necessarily
> a good place to clean dummy object.

I agree that this isn't necessarily the best place to do this in the
kexec case, but given we control the firmware, figuring out what's
actually breaking seems like a good plan.