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Date: Wed, 9 Aug 2017 11:16:48 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Juergen Gross <jgross@suse.com>
Cc: Andy Lutomirski <luto@kernel.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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        Jiri Slaby <jslaby@suse.cz>, Ingo Molnar <mingo@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Mike Galbraith <efault@gmx.de>
Subject: Re: [PATCH v4 1/2] x86/unwind: add ORC unwinder
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On Wed, Aug 09, 2017 at 10:49:43AM +0200, Juergen Gross wrote:
> > ALTERNATIVE "pushfq; popq %rax", "callq *pv_irq_ops.save_fl",
> > X86_FEATURE_GODDAMN_PV_IRQ_OPS
> 
> You are aware that at least some of the Xen irq pvops functionality is
> patched inline? Your modification would slow down pv guests quite a
> bit, I guess.

Where does that live? I know of the inline patching for native, but
didn't know the guests did any of that too.