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Date:   Wed, 8 Apr 2020 11:13:06 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Jan Kiszka <jan.kiszka@siemens.com>
Cc:     Steven Rostedt <rostedt@goodmis.org>, tglx@linutronix.de,
        linux-kernel@vger.kernel.org, hch@infradead.org,
        sean.j.christopherson@intel.com, mingo@redhat.com, bp@alien8.de,
        hpa@zytor.com, x86@kernel.org, kenny@panix.com, jeyu@kernel.org,
        rasmus.villemoes@prevas.dk, pbonzini@redhat.com,
        fenghua.yu@intel.com, xiaoyao.li@intel.com, nadav.amit@gmail.com,
        thellstrom@vmware.com, tony.luck@intel.com,
        gregkh@linuxfoundation.org, jannh@google.com,
        keescook@chromium.org, David.Laight@aculab.com,
        dcovelli@vmware.com, mhiramat@kernel.org,
        Wolfgang Mauerer <wolfgang.mauerer@oth-regensburg.de>
Subject: Re: [PATCH 4/4] x86,module: Detect CRn and DRn manipulation
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On Wed, Apr 08, 2020 at 10:51:38AM +0200, Peter Zijlstra wrote:
> On Wed, Apr 08, 2020 at 07:58:53AM +0200, Jan Kiszka wrote:
> > On 07.04.20 23:48, Steven Rostedt wrote:
> 
> > > Hmm, wont this break jailhouse?
> 
> Breaking it isn't a problem, it's out of tree and it should be fixable.
> 
> > Yes, possibly. We load the hypervisor binary via request_firmware into
> > executable memory and then jump into it. So most of the "suspicious" code is
> 
> W.T.H. does the firmware loader have the ability to give executable
> memory? We need to kill that too. /me goes find.

AFAICT the firmware loader only provides PAGE_KERNEL_RO, so how do you
get it executable?

I'm thinking the patches Christoph has lined up will take care of this.