From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D2F64C52D7C for ; Thu, 22 Aug 2024 16:19:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Q8XKnc0XBARsVPQpuEIz81+11vl6+Ld+VEZ7OM6ATq0=; b=KRAjeBcVWd+NeDlK7D6Ek37GxJ cN/+O+8Lr+XWD4RfhMMZWBnE7aY3Km4YwKZ/+AhVqWy+fLobkHuNnzCcMBoPEmxUaQv1eyo986rRe J9epGEHcE/BsFjWyrtT977CguQuFjRrU+SqQeG6gTHPCPK9wdvVK+a+OPRtDHSuB6T6Lj4b7MEkQn jYh0qogEe7uoCf4O5rN7XFv6C88TLWYAKWpiSrcCCcAFDwyhH25mljNTzWLi5QT7YQ1EpKqq/s2DW N8fTFmGF/CQo4WBGE+JlSTZfRO3kK5VHffP+yxMx99nJV46+vEEUhaORj2lif5HfLWEPDTHbr2SWc l/aXprqg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1shAWc-0000000DZ4E-0ihA; Thu, 22 Aug 2024 16:19:02 +0000 Received: from nyc.source.kernel.org ([2604:1380:45d1:ec00::3]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1shAV1-0000000DYZN-1foG; Thu, 22 Aug 2024 16:17:24 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 0683AA40B24; Thu, 22 Aug 2024 16:17:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7A5ABC32782; Thu, 22 Aug 2024 16:17:16 +0000 (UTC) Date: Thu, 22 Aug 2024 17:17:14 +0100 From: Catalin Marinas To: Mark Brown Cc: Will Deacon , Jonathan Corbet , Andrew Morton , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Arnd Bergmann , Oleg Nesterov , Eric Biederman , Shuah Khan , "Rick P. Edgecombe" , Deepak Gupta , Ard Biesheuvel , Szabolcs Nagy , Kees Cook , "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Florian Weimer , Christian Brauner , Thiago Jung Bauermann , Ross Burton , Yury Khrustalev , Wilco Dijkstra , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH v11 21/39] arm64/gcs: Ensure that new threads have a GCS Message-ID: References: <20240822-arm64-gcs-v11-0-41b81947ecb5@kernel.org> <20240822-arm64-gcs-v11-21-41b81947ecb5@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240822-arm64-gcs-v11-21-41b81947ecb5@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240822_091723_520044_7C3F1DC6 X-CRM114-Status: GOOD ( 13.54 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Aug 22, 2024 at 02:15:24AM +0100, Mark Brown wrote: > @@ -512,10 +538,16 @@ static void gcs_thread_switch(struct task_struct *next) > gcs_set_el0_mode(next); > > /* > - * Ensure that GCS changes are observable by/from other PEs in > - * case of migration. > + * Ensure that GCS memory effects of the 'prev' thread are > + * ordered before other memory accesses with release semantics > + * (or preceded by a DMB) on the current PE. In addition, any > + * memory accesses with acquire semantics (or succeeded by a > + * DMB) are ordered before GCS memory effects of the 'next' > + * thread. This will ensure that the GCS memory effects are > + * visible to other PEs in case of migration. > */ > - gcsb_dsync(); > + if (task_gcs_el0_enabled(current) || task_gcs_el0_enabled(next)) > + gcsb_dsync(); > } Ah, the comment turned up in this patch. It looks fine. Reviewed-by: Catalin Marinas