From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751314AbeBTIfR (ORCPT ); Tue, 20 Feb 2018 03:35:17 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:60753 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750703AbeBTIfQ (ORCPT ); Tue, 20 Feb 2018 03:35:16 -0500 Date: Tue, 20 Feb 2018 09:35:25 +0100 (CET) From: Thomas Gleixner To: David Woodhouse cc: karahmed@amazon.de, x86@kernel.org, kvm@vger.kernel.org, torvalds@linux-foundation.org, pbonzini@redhat.com, linux-kernel@vger.kernel.org, bp@alien8.de, peterz@infradead.org, jmattson@google.com, rkrcmar@redhat.com, arjan.van.de.ven@intel.com, dave.hansen@intel.com, mingo@kernel.org Subject: Re: [PATCH v3 3/4] Revert "x86/retpoline: Simplify vmexit_fill_RSB()" In-Reply-To: <1519037457-7643-4-git-send-email-dwmw@amazon.co.uk> Message-ID: References: <1519037457-7643-1-git-send-email-dwmw@amazon.co.uk> <1519037457-7643-4-git-send-email-dwmw@amazon.co.uk> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 19 Feb 2018, David Woodhouse wrote: > This reverts commit 1dde7415e99933bb7293d6b2843752cbdb43ec11. By putting > the RSB filling out of line and calling it, we waste one RSB slot for > returning from the function itself, which means one fewer actual function > call we can make if we're doing the Skylake abomination of call-depth > counting. > > It also changed the number of RSB stuffings we do on vmexit from 32, > which was correct, to 16. Let's just stop with the bikeshedding; it > didn't actually *fix* anything anyway. > > Signed-off-by: David Woodhouse Acked-by: Thomas Gleixner