linux-kernel - Re: [PATCH] x86/EISA: Don't probe EISA bus for Xen PV guests

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Message-ID: <340bfde6-6cf8-ce15-2327-7484abd351e0@oracle.com>
Date:   Tue, 11 Sep 2018 16:30:11 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     mingo@...hat.com, hpa@...or.com, x86@...nel.org,
        linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
        jgross@...e.com, andy@...ugglers.net,
        stable <stable@...r.kernel.org>
Subject: Re: [PATCH] x86/EISA: Don't probe EISA bus for Xen PV guests

On 9/11/18 4:20 PM, Thomas Gleixner wrote:
> On Tue, 11 Sep 2018, Boris Ostrovsky wrote:
>
>> For unprivileged Xen PV guests this is normal memory and ioremap will
>> not be able to properly map it.
>>
>> While at it, since ioremap may return NULL, add a test for pointer's
>> validity.
> I assume this goes back to very dead kernels, so that should go with a Cc
> stable, right?
>


Yes, I forgot to add those (and now I did), thanks for pointing this out.

It has to go at least all the way back to 4.13 since before
f7eaf6e00fd58 ("x86/boot: Move EISA setup to a separate file"), just by
luck, early_ioremap() worked for the guests.


-boris