linux-kernel - Re: [PATCH 2/2] x86/Xen/32: simplify xen_iret_crit

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Message-ID: <fcfc2cc3-4f98-882d-ed14-d6e2e4d8731d@suse.com>
Date:   Tue, 19 Nov 2019 14:18:15 +0100
From:   Jürgen Groß <jgross@...e.com>
To:     Jan Beulich <jbeulich@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>
Subject: Re: [PATCH 2/2] x86/Xen/32: simplify xen_iret_crit_fixup's ring check

On 11.11.19 15:32, Jan Beulich wrote:
> This can be had with two instead of six insns, by just checking the high
> CS.RPL bit.
> 
> Also adjust the comment - there would be no #GP in the mentioned cases,
> as there's no segment limit violation or alike. Instead there'd be #PF,
> but that one reports the target EIP of said branch, not the address of
> the branch insn itself.
> 
> Signed-off-by: Jan Beulich <jbeulich@...e.com>

Reviewed-by: Juergen Gross <jgross@...e.com>


Juergen