linux-kernel - Re: [PATCH v2 0/4] Remove 32-bit Xen PV guest support

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Date:   Thu, 2 Jul 2020 17:45:23 +0200
From:   Jürgen Groß <jgross@...e.com>
To:     Brian Gerst <brgerst@...il.com>
Cc:     xen-devel <xen-devel@...ts.xenproject.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Virtualization <virtualization@...ts.linux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Deep Shah <sdeep@...are.com>,
        "VMware, Inc." <pv-drivers@...are.com>
Subject: Re: [PATCH v2 0/4] Remove 32-bit Xen PV guest support

On 02.07.20 16:48, Brian Gerst wrote:
> On Wed, Jul 1, 2020 at 7:07 AM Juergen Gross <jgross@...e.com> wrote:
>>
>> The long term plan has been to replace Xen PV guests by PVH. The first
>> victim of that plan are now 32-bit PV guests, as those are used only
>> rather seldom these days. Xen on x86 requires 64-bit support and with
>> Grub2 now supporting PVH officially since version 2.04 there is no
>> need to keep 32-bit PV guest support alive in the Linux kernel.
>> Additionally Meltdown mitigation is not available in the kernel running
>> as 32-bit PV guest, so dropping this mode makes sense from security
>> point of view, too.
> 
> One thing that you missed is removing VDSO_NOTE_NONEGSEG_BIT from
> vdso32/note.S.  With that removed there is no difference from the
> 64-bit version.

Oh, this means we can probably remove arch/x86/xen/vdso.h completely.

> 
> Otherwise this series looks good to me.

Thanks,


Juergen