From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753187AbaIAJee (ORCPT ); Mon, 1 Sep 2014 05:34:34 -0400 Received: from fw-tnat.austin.arm.com ([217.140.110.23]:11339 "EHLO collaborate-mta1.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752207AbaIAJed (ORCPT ); Mon, 1 Sep 2014 05:34:33 -0400 Date: Mon, 1 Sep 2014 10:34:28 +0100 From: Catalin Marinas To: Leo Yan Cc: "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "ard.biesheuvel@linaro.org" , Will Deacon Subject: Re: [PATCH v2] arm64: fix bug for reloading FPSIMD state after cpu power off Message-ID: <20140901093427.GC608@arm.com> References: <1409540991-7573-1-git-send-email-leoy@marvell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1409540991-7573-1-git-send-email-leoy@marvell.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 01, 2014 at 04:09:51AM +0100, Leo Yan wrote: > Now arm64 defers reloading FPSIMD state, but this optimization also > introduces the bug after cpu resume back from low power mode. > > The reason is after the cpu has been powered off, s/w need set the > cpu's fpsimd_last_state to NULL so that it will force to reload > FPSIMD state for the thread, otherwise there has the chance to meet > the condition for both the task's fpsimd_state.cpu field contains the > id of the current cpu, and the cpu's fpsimd_last_state per-cpu variable > points to the task's fpsimd_state, so finally kernel will skip to reload > the context during it return back to userland. > > Signed-off-by: Leo Yan Reviewed-by: Catalin Marinas (and cc'ing Will to pick it up since he's handling the 3.17 release) Thanks.