linux-kernel - Re: [PATCH] x86/retpoline: Also fill return buffer after idle

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Message-ID: <20180109002407.GF6718@tassilo.jf.intel.com>
Date:   Mon, 8 Jan 2018 16:24:07 -0800
From:   Andi Kleen <ak@...ux.intel.com>
To:     David Woodhouse <dwmw2@...radead.org>
Cc:     Andi Kleen <andi@...stfloor.org>, pjt@...gle.com,
        linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
        gregkh@...ux-foundation.org, tim.c.chen@...ux.intel.com,
        dave.hansen@...el.com, tglx@...utronix.de, peterz@...radead.org,
        luto@...capital.net
Subject: Re: [PATCH] x86/retpoline: Also fill return buffer after idle

> Probably doesn't matter right there but it's going to end up being used
> elsewhere with IBRS/IBPB, and the compiler is going to think it needs
> to save all the call-clobbered registers for that. Do we want to make
> it use inline asm instead?

You mean KVM?

All the other places have lots of other calls too, so the registers are likely 
already clobbered.

-Andi