From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 35FFCC5F7 for ; Tue, 14 Feb 2023 20:19:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 40F00C433EF; Tue, 14 Feb 2023 20:19:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1676405952; bh=8/V8zQrKDfVgeKbs27WthihxgwdivBHQ1xvEeA6uoYs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vQOpB4jZU06j0E1MKDDJZEPPNRmXS0/cOAjGFTxoXLPrgQIK/B47hTb0QFcKIneZb s0jPY923NwwG0EAaHw8yq2VeY+rnIZejt5UaWx/A6Novye6lAoPweaDLN/vVDTfV4/ z2wbU080F9o3lsW1XlbaHeONXQOQPrvD/SUfEbdGlUuV0/0zX3LoW10/MVrsarzBdE ceX7Oa5FeZeJLYpScL4JzHvW13XbOGzyYkvzihDtHpZE/AnlwkFrJ1ZK6bjfdTEzD6 0YVc817WUB5hgfgY4gpdM1zFQ3vDBu3uys4X8js6W3ZOQyDxWfawx8vYr8MN57D9M7 IlAUpkSGii2pg== Date: Tue, 14 Feb 2023 12:19:09 -0800 From: Josh Poimboeuf To: Max Filippov Cc: juri.lelli@redhat.com, dalias@libc.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, peterz@infradead.org, catalin.marinas@arm.com, dave.hansen@linux.intel.com, x86@kernel.org, jiaxun.yang@flygoat.com, linux-mips@vger.kernel.org, bsegall@google.com, guoren@kernel.org, hpa@zytor.com, sparclinux@vger.kernel.org, kernel@xen0n.name, will@kernel.org, vschneid@redhat.com, f.fainelli@gmail.com, vincent.guittot@linaro.org, ysato@users.sourceforge.jp, chenhuacai@kernel.org, linux@armlinux.org.uk, linux-csky@vger.kernel.org, mingo@redhat.com, bcm-kernel-feedback-list@broadcom.com, mgorman@suse.de, mattst88@gmail.com, linux-xtensa@linux-xtensa.org, paulmck@kernel.org, richard.henderson@linaro.org, npiggin@gmail.com, ink@jurassic.park.msu.ru, rostedt@goodmis.org, loongarch@lists.linux.dev, tglx@linutronix.de, dietmar.eggemann@arm.com, linux-arm-kernel@lists.infradead.org, jgross@suse.com, chris@zankel.net, tsbogend@alpha.franken.de, Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , bristot@redhat.com, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, bp@alien8.de, linuxppc-dev@lists.ozlabs.org, davem@davemloft.net Subject: Re: [PATCH v2 19/24] xtensa/cpu: Make sure cpu_die() doesn't return Message-ID: <20230214201909.flqc3g3njnbl5hun@treble> References: <1b4afd82-83cb-0060-7cab-8e16d2e69ff9@linaro.org> <20230214182322.r5tyeowxzloiuh72@treble> Precedence: bulk X-Mailing-List: loongarch@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Feb 14, 2023 at 11:48:41AM -0800, Max Filippov wrote: > On Tue, Feb 14, 2023 at 10:23 AM Josh Poimboeuf wrote: > > On Tue, Feb 14, 2023 at 08:55:32AM +0100, Philippe Mathieu-Daudé wrote: > > > Can you update the documentation along? Currently we have: > > > > > > /* > > > * Called from the idle thread for the CPU which has been shutdown. > > > * > > > * Note that we disable IRQs here, but do not re-enable them > > > * before returning to the caller. This is also the behaviour > > > * of the other hotplug-cpu capable cores, so presumably coming > > > * out of idle fixes this. > > > */ > > > > void __ref cpu_die(void) > > { > > idle_task_exit(); > > local_irq_disable(); > > __asm__ __volatile__( > > " movi a2, cpu_restart\n" > > " jx a2\n"); > > > > BUG(); > > } > > > > Hm, not only is the comment wrong, but it seems to be branching to > > cpu_restart? That doesn't seem right at all. > > Perhaps the name is a bit misleading. The CPU that enters 'cpu_restart' > loops there until a call to 'boot_secondary' releases it, after which it goes > to '_startup'. So it is a restart, but not immediate. Ah, I see. That sounds similar to what Xen does. -- Josh 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 E8230C61DA4 for ; Tue, 14 Feb 2023 20:20:14 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4PGXd91sVTz3cd4 for ; Wed, 15 Feb 2023 07:20:13 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=vQOpB4jZ; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=145.40.68.75; helo=ams.source.kernel.org; envelope-from=jpoimboe@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=vQOpB4jZ; dkim-atps=neutral Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4PGXc54bBSz3cCL for ; Wed, 15 Feb 2023 07:19:17 +1100 (AEDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 1D095B81F0A; Tue, 14 Feb 2023 20:19:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 40F00C433EF; Tue, 14 Feb 2023 20:19:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1676405952; bh=8/V8zQrKDfVgeKbs27WthihxgwdivBHQ1xvEeA6uoYs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vQOpB4jZU06j0E1MKDDJZEPPNRmXS0/cOAjGFTxoXLPrgQIK/B47hTb0QFcKIneZb s0jPY923NwwG0EAaHw8yq2VeY+rnIZejt5UaWx/A6Novye6lAoPweaDLN/vVDTfV4/ z2wbU080F9o3lsW1XlbaHeONXQOQPrvD/SUfEbdGlUuV0/0zX3LoW10/MVrsarzBdE ceX7Oa5FeZeJLYpScL4JzHvW13XbOGzyYkvzihDtHpZE/AnlwkFrJ1ZK6bjfdTEzD6 0YVc817WUB5hgfgY4gpdM1zFQ3vDBu3uys4X8js6W3ZOQyDxWfawx8vYr8MN57D9M7 IlAUpkSGii2pg== Date: Tue, 14 Feb 2023 12:19:09 -0800 From: Josh Poimboeuf To: Max Filippov Subject: Re: [PATCH v2 19/24] xtensa/cpu: Make sure cpu_die() doesn't return Message-ID: <20230214201909.flqc3g3njnbl5hun@treble> References: <1b4afd82-83cb-0060-7cab-8e16d2e69ff9@linaro.org> <20230214182322.r5tyeowxzloiuh72@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: juri.lelli@redhat.com, dalias@libc.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, peterz@infradead.org, catalin.marinas@arm.com, dave.hansen@linux.intel.com, x86@kernel.org, jiaxun.yang@flygoat.com, linux-kernel@vger.kernel.org, bsegall@google.com, guoren@kernel.org, hpa@zytor.com, sparclinux@vger.kernel.org, kernel@xen0n.name, will@kernel.org, vschneid@redhat.com, f.fainelli@gmail.com, vincent.guittot@linaro.org, ysato@users.sourceforge.jp, chenhuacai@kernel.org, linux@armlinux.org.uk, linux-csky@vger.kernel.org, mingo@redhat.com, bcm-kernel-feedback-list@broadcom.com, mgorman@suse.de, mattst88@gmail.com, linux-xtensa@linux-xtensa.org, paulmck@kernel.org, richard.henderson@linaro.org, npiggin@gmail.com, ink@jurassic.park.msu.ru, rostedt@goodmis.org, loongarch@lists.linux.dev, tglx@linutronix.de, dietmar.eggemann@arm.com, linux-arm-kernel@lists.infradead.org, jgross@suse.com, chris@zankel.net, tsbogend@alpha.franken.de, Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , linuxppc-dev@lists.ozlabs.org, linux-mips@vger.kernel.org, linux-alpha@vger.kernel.org, bp@alien8.de, bristot@redhat.com, davem@davemloft.net Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Feb 14, 2023 at 11:48:41AM -0800, Max Filippov wrote: > On Tue, Feb 14, 2023 at 10:23 AM Josh Poimboeuf wrote: > > On Tue, Feb 14, 2023 at 08:55:32AM +0100, Philippe Mathieu-Daudé wrote: > > > Can you update the documentation along? Currently we have: > > > > > > /* > > > * Called from the idle thread for the CPU which has been shutdown. > > > * > > > * Note that we disable IRQs here, but do not re-enable them > > > * before returning to the caller. This is also the behaviour > > > * of the other hotplug-cpu capable cores, so presumably coming > > > * out of idle fixes this. > > > */ > > > > void __ref cpu_die(void) > > { > > idle_task_exit(); > > local_irq_disable(); > > __asm__ __volatile__( > > " movi a2, cpu_restart\n" > > " jx a2\n"); > > > > BUG(); > > } > > > > Hm, not only is the comment wrong, but it seems to be branching to > > cpu_restart? That doesn't seem right at all. > > Perhaps the name is a bit misleading. The CPU that enters 'cpu_restart' > loops there until a call to 'boot_secondary' releases it, after which it goes > to '_startup'. So it is a restart, but not immediate. Ah, I see. That sounds similar to what Xen does. -- Josh 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 C1DDAC05027 for ; Tue, 14 Feb 2023 20:20:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=wJ7tC0Gfdee/DhxXLWTDd/1SLqHbRuN1RTHJy9nbG5Q=; b=fi5eunr5wKGvei VQoKMA1H+E1QlgcAQGSmQL3H9tnHQ4v+SNL2whCxnVCHhAVzHinu521zm+xW67JcAY3YA52n2naOJ ctsg39vgCMAghi8OVQfmHnw4EpfQPGFSshufaWIRrcbpTz7JuRQRMEK916Ed1jtMNsizaw+tG97jY fA70h8uXKvcrkyUG4csEyMwaZGSO7bzwvRBbo7e2TQ9lkcVOBhOoUaOnDRQezx7Iny/EDWcUO5Bx7 ADgYO4YzDYtulg4MFxQ/75oeRxdfIYQFAdJGrsg/6E8rIa4GHyi3pSdGI1EYtfUTXfQR41MnKStHL xlhpz8PGSVejRxXTRm2g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pS1lm-003NHK-OO; Tue, 14 Feb 2023 20:19:18 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1pS1lj-003NFl-Px for linux-arm-kernel@lists.infradead.org; Tue, 14 Feb 2023 20:19:17 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 1D095B81F0A; Tue, 14 Feb 2023 20:19:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 40F00C433EF; Tue, 14 Feb 2023 20:19:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1676405952; bh=8/V8zQrKDfVgeKbs27WthihxgwdivBHQ1xvEeA6uoYs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vQOpB4jZU06j0E1MKDDJZEPPNRmXS0/cOAjGFTxoXLPrgQIK/B47hTb0QFcKIneZb s0jPY923NwwG0EAaHw8yq2VeY+rnIZejt5UaWx/A6Novye6lAoPweaDLN/vVDTfV4/ z2wbU080F9o3lsW1XlbaHeONXQOQPrvD/SUfEbdGlUuV0/0zX3LoW10/MVrsarzBdE ceX7Oa5FeZeJLYpScL4JzHvW13XbOGzyYkvzihDtHpZE/AnlwkFrJ1ZK6bjfdTEzD6 0YVc817WUB5hgfgY4gpdM1zFQ3vDBu3uys4X8js6W3ZOQyDxWfawx8vYr8MN57D9M7 IlAUpkSGii2pg== Date: Tue, 14 Feb 2023 12:19:09 -0800 From: Josh Poimboeuf To: Max Filippov Cc: juri.lelli@redhat.com, dalias@libc.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, peterz@infradead.org, catalin.marinas@arm.com, dave.hansen@linux.intel.com, x86@kernel.org, jiaxun.yang@flygoat.com, linux-mips@vger.kernel.org, bsegall@google.com, guoren@kernel.org, hpa@zytor.com, sparclinux@vger.kernel.org, kernel@xen0n.name, will@kernel.org, vschneid@redhat.com, f.fainelli@gmail.com, vincent.guittot@linaro.org, ysato@users.sourceforge.jp, chenhuacai@kernel.org, linux@armlinux.org.uk, linux-csky@vger.kernel.org, mingo@redhat.com, bcm-kernel-feedback-list@broadcom.com, mgorman@suse.de, mattst88@gmail.com, linux-xtensa@linux-xtensa.org, paulmck@kernel.org, richard.henderson@linaro.org, npiggin@gmail.com, ink@jurassic.park.msu.ru, rostedt@goodmis.org, loongarch@lists.linux.dev, tglx@linutronix.de, dietmar.eggemann@arm.com, linux-arm-kernel@lists.infradead.org, jgross@suse.com, chris@zankel.net, tsbogend@alpha.franken.de, Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , bristot@redhat.com, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, bp@alien8.de, linuxppc-dev@lists.ozlabs.org, davem@davemloft.net Subject: Re: [PATCH v2 19/24] xtensa/cpu: Make sure cpu_die() doesn't return Message-ID: <20230214201909.flqc3g3njnbl5hun@treble> References: <1b4afd82-83cb-0060-7cab-8e16d2e69ff9@linaro.org> <20230214182322.r5tyeowxzloiuh72@treble> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230214_121916_137285_99E3021D X-CRM114-Status: GOOD ( 21.38 ) 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: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gVHVlLCBGZWIgMTQsIDIwMjMgYXQgMTE6NDg6NDFBTSAtMDgwMCwgTWF4IEZpbGlwcG92IHdy b3RlOgo+IE9uIFR1ZSwgRmViIDE0LCAyMDIzIGF0IDEwOjIzIEFNIEpvc2ggUG9pbWJvZXVmIDxq cG9pbWJvZUBrZXJuZWwub3JnPiB3cm90ZToKPiA+IE9uIFR1ZSwgRmViIDE0LCAyMDIzIGF0IDA4 OjU1OjMyQU0gKzAxMDAsIFBoaWxpcHBlIE1hdGhpZXUtRGF1ZMOpIHdyb3RlOgo+ID4gPiBDYW4g eW91IHVwZGF0ZSB0aGUgZG9jdW1lbnRhdGlvbiBhbG9uZz8gQ3VycmVudGx5IHdlIGhhdmU6Cj4g PiA+Cj4gPiA+ICAgLyoKPiA+ID4gICAgKiBDYWxsZWQgZnJvbSB0aGUgaWRsZSB0aHJlYWQgZm9y IHRoZSBDUFUgd2hpY2ggaGFzIGJlZW4gc2h1dGRvd24uCj4gPiA+ICAgICoKPiA+ID4gICAgKiBO b3RlIHRoYXQgd2UgZGlzYWJsZSBJUlFzIGhlcmUsIGJ1dCBkbyBub3QgcmUtZW5hYmxlIHRoZW0K PiA+ID4gICAgKiBiZWZvcmUgcmV0dXJuaW5nIHRvIHRoZSBjYWxsZXIuIFRoaXMgaXMgYWxzbyB0 aGUgYmVoYXZpb3VyCj4gPiA+ICAgICogb2YgdGhlIG90aGVyIGhvdHBsdWctY3B1IGNhcGFibGUg Y29yZXMsIHNvIHByZXN1bWFibHkgY29taW5nCj4gPiA+ICAgICogb3V0IG9mIGlkbGUgZml4ZXMg dGhpcy4KPiA+ID4gICAgKi8KPiA+Cj4gPiB2b2lkIF9fcmVmIGNwdV9kaWUodm9pZCkKPiA+IHsK PiA+ICAgICAgICAgaWRsZV90YXNrX2V4aXQoKTsKPiA+ICAgICAgICAgbG9jYWxfaXJxX2Rpc2Fi bGUoKTsKPiA+ICAgICAgICAgX19hc21fXyBfX3ZvbGF0aWxlX18oCj4gPiAgICAgICAgICAgICAg ICAgICAgICAgICAiICAgICAgIG1vdmkgICAgYTIsIGNwdV9yZXN0YXJ0XG4iCj4gPiAgICAgICAg ICAgICAgICAgICAgICAgICAiICAgICAgIGp4ICAgICAgYTJcbiIpOwo+ID4KPiA+ICAgICAgICAg QlVHKCk7Cj4gPiB9Cj4gPgo+ID4gSG0sIG5vdCBvbmx5IGlzIHRoZSBjb21tZW50IHdyb25nLCBi dXQgaXQgc2VlbXMgdG8gYmUgYnJhbmNoaW5nIHRvCj4gPiBjcHVfcmVzdGFydD8gIFRoYXQgZG9l c24ndCBzZWVtIHJpZ2h0IGF0IGFsbC4KPiAKPiBQZXJoYXBzIHRoZSBuYW1lIGlzIGEgYml0IG1p c2xlYWRpbmcuIFRoZSBDUFUgdGhhdCBlbnRlcnMgJ2NwdV9yZXN0YXJ0Jwo+IGxvb3BzIHRoZXJl IHVudGlsIGEgY2FsbCB0byAnYm9vdF9zZWNvbmRhcnknIHJlbGVhc2VzIGl0LCBhZnRlciB3aGlj aCBpdCBnb2VzCj4gdG8gJ19zdGFydHVwJy4gU28gaXQgaXMgYSByZXN0YXJ0LCBidXQgbm90IGlt bWVkaWF0ZS4KCkFoLCBJIHNlZS4gIFRoYXQgc291bmRzIHNpbWlsYXIgdG8gd2hhdCBYZW4gZG9l cy4KCi0tIApKb3NoCgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fXwpsaW51eC1hcm0ta2VybmVsIG1haWxpbmcgbGlzdApsaW51eC1hcm0ta2VybmVsQGxpc3Rz LmluZnJhZGVhZC5vcmcKaHR0cDovL2xpc3RzLmluZnJhZGVhZC5vcmcvbWFpbG1hbi9saXN0aW5m by9saW51eC1hcm0ta2VybmVsCg== From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Poimboeuf Date: Tue, 14 Feb 2023 20:19:09 +0000 Subject: Re: [PATCH v2 19/24] xtensa/cpu: Make sure cpu_die() doesn't return Message-Id: <20230214201909.flqc3g3njnbl5hun@treble> List-Id: References: <1b4afd82-83cb-0060-7cab-8e16d2e69ff9@linaro.org> <20230214182322.r5tyeowxzloiuh72@treble> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Max Filippov Cc: juri.lelli@redhat.com, dalias@libc.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, peterz@infradead.org, catalin.marinas@arm.com, dave.hansen@linux.intel.com, x86@kernel.org, jiaxun.yang@flygoat.com, linux-mips@vger.kernel.org, bsegall@google.com, guoren@kernel.org, hpa@zytor.com, sparclinux@vger.kernel.org, kernel@xen0n.name, will@kernel.org, vschneid@redhat.com, f.fainelli@gmail.com, vincent.guittot@linaro.org, ysato@users.sourceforge.jp, chenhuacai@kernel.org, linux@armlinux.org.uk, linux-csky@vger.kernel.org, mingo@redhat.com, bcm-kernel-feedback-list@broadcom.com, mgorman@suse.de, mattst88@gmail.com, linux-xtensa@linux-xtensa.org, paulmck@kernel.org, richard.henderson@linaro.org, npiggin@gmail.com, ink@jurassic.park.msu.ru, rostedt@goodmis.org, loongarch@lists.linux.dev, tglx@linutronix.de, dietmar.eggemann@arm.com, linux-arm-kernel@lists.infradead.org, jgross@suse.com, chris@zankel.net, tsbogend@alpha.franken.de, Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , bristot@redhat.com, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, bp@alien8.de, linuxppc-dev@lists.ozlabs.org, davem@davemloft.net On Tue, Feb 14, 2023 at 11:48:41AM -0800, Max Filippov wrote: > On Tue, Feb 14, 2023 at 10:23 AM Josh Poimboeuf wro= te: > > On Tue, Feb 14, 2023 at 08:55:32AM +0100, Philippe Mathieu-Daud=C3=A9 w= rote: > > > Can you update the documentation along? Currently we have: > > > > > > /* > > > * Called from the idle thread for the CPU which has been shutdown. > > > * > > > * Note that we disable IRQs here, but do not re-enable them > > > * before returning to the caller. This is also the behaviour > > > * of the other hotplug-cpu capable cores, so presumably coming > > > * out of idle fixes this. > > > */ > > > > void __ref cpu_die(void) > > { > > idle_task_exit(); > > local_irq_disable(); > > __asm__ __volatile__( > > " movi a2, cpu_restart\n" > > " jx a2\n"); > > > > BUG(); > > } > > > > Hm, not only is the comment wrong, but it seems to be branching to > > cpu_restart? That doesn't seem right at all. >=20 > Perhaps the name is a bit misleading. The CPU that enters 'cpu_restart' > loops there until a call to 'boot_secondary' releases it, after which it = goes > to '_startup'. So it is a restart, but not immediate. Ah, I see. That sounds similar to what Xen does. --=20 Josh From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Poimboeuf Subject: Re: [PATCH v2 19/24] xtensa/cpu: Make sure cpu_die() doesn't return Date: Tue, 14 Feb 2023 12:19:09 -0800 Message-ID: <20230214201909.flqc3g3njnbl5hun@treble> References: <1b4afd82-83cb-0060-7cab-8e16d2e69ff9@linaro.org> <20230214182322.r5tyeowxzloiuh72@treble> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1676405952; bh=8/V8zQrKDfVgeKbs27WthihxgwdivBHQ1xvEeA6uoYs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vQOpB4jZU06j0E1MKDDJZEPPNRmXS0/cOAjGFTxoXLPrgQIK/B47hTb0QFcKIneZb s0jPY923NwwG0EAaHw8yq2VeY+rnIZejt5UaWx/A6Novye6lAoPweaDLN/vVDTfV4/ z2wbU080F9o3lsW1XlbaHeONXQOQPrvD/SUfEbdGlUuV0/0zX3LoW10/MVrsarzBdE ceX7Oa5FeZeJLYpScL4JzHvW13XbOGzyYkvzihDtHpZE/AnlwkFrJ1ZK6bjfdTEzD6 0YVc817WUB5hgfgY4gpdM1zFQ3vDBu3uys4X8js6W3ZOQyDxWfawx8vYr8MN57D9M7 IlAUpkSGii2pg== Content-Disposition: inline In-Reply-To: List-ID: Content-Type: text/plain; charset="iso-8859-1" To: Max Filippov Cc: juri.lelli@redhat.com, dalias@libc.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, peterz@infradead.org, catalin.marinas@arm.com, dave.hansen@linux.intel.com, x86@kernel.org, jiaxun.yang@flygoat.com, linux-mips@vger.kernel.org, bsegall@google.com, guoren@kernel.org, hpa@zytor.com, sparclinux@vger.kernel.org, kernel@xen0n.name, will@kernel.org, vschneid@redhat.com, f.fainelli@gmail.com, vincent.guittot@linaro.org, ysato@users.sourceforge.jp, chenhuacai@kernel.org, linux@armlinux.org.uk, linux-csky@vger.kernel.org, mingo@redhat.com, bcm-kernel-feedback-list@broadcom.com, mgorman@suse.de, mattst88@gmail.com, linux-xtensa@linux-xtensa.org, paulmck@kernel.org, richard.henderson@linaro.org, npiggin@gmail.com, ink@jurassic.park.msu.ru, rostedt@goodmis.org, loongarch@lis On Tue, Feb 14, 2023 at 11:48:41AM -0800, Max Filippov wrote: > On Tue, Feb 14, 2023 at 10:23 AM Josh Poimboeuf wro= te: > > On Tue, Feb 14, 2023 at 08:55:32AM +0100, Philippe Mathieu-Daud=C3=A9 w= rote: > > > Can you update the documentation along? Currently we have: > > > > > > /* > > > * Called from the idle thread for the CPU which has been shutdown. > > > * > > > * Note that we disable IRQs here, but do not re-enable them > > > * before returning to the caller. This is also the behaviour > > > * of the other hotplug-cpu capable cores, so presumably coming > > > * out of idle fixes this. > > > */ > > > > void __ref cpu_die(void) > > { > > idle_task_exit(); > > local_irq_disable(); > > __asm__ __volatile__( > > " movi a2, cpu_restart\n" > > " jx a2\n"); > > > > BUG(); > > } > > > > Hm, not only is the comment wrong, but it seems to be branching to > > cpu_restart? That doesn't seem right at all. >=20 > Perhaps the name is a bit misleading. The CPU that enters 'cpu_restart' > loops there until a call to 'boot_secondary' releases it, after which it = goes > to '_startup'. So it is a restart, but not immediate. Ah, I see. That sounds similar to what Xen does. --=20 Josh