linux-kernel - Re: 5.7.0 / BUG: kernel NULL pointer dereference / setup_cpu

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Message-ID: <a467c2db-e72d-9a27-9fbd-9bcf8770de20@citrix.com>
Date:   Fri, 5 Jun 2020 19:10:13 +0100
From:   Andrew Cooper <andrew.cooper3@...rix.com>
To:     Christian Kujau <lists@...dbynature.de>,
        <linux-kernel@...r.kernel.org>
CC:     <xen-devel@...ts.xenproject.org>, Juergen Gross <jgross@...e.com>,
        Roger Pau Monné <roger.pau@...rix.com>
Subject: Re: 5.7.0 / BUG: kernel NULL pointer dereference / setup_cpu_watcher

On 05/06/2020 09:36, Christian Kujau wrote:
> Hi,
>
> I'm running a small Xen PVH domain and upgrading from vanilla 5.6.0 to 
> <snip>
>
> Note: that "Xen Platform PCI: unrecognised magic value" on the top appears 
> in 5.6 kernels as well, but no ill effects so far.
>
> ---------------------------------------------------------------
> Xen Platform PCI: unrecognised magic value

PVH domains don't have the emulated platform device, so Linux will be
finding ~0 when it goes looking in config space.

The diagnostic should be skipped in that case, to avoid giving the false
impression that something is wrong.

~Andrew