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 B9B83EB64D9 for ; Tue, 4 Jul 2023 19:00:18 +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=ga/DeKPdqVOGom1469X+txoaujGk9IsoSVAF1xMyOnU=; b=WjymRLIpkY2zgh mdsTm40B26BK+iei8ipvbGkiwn+Wy+rna9hm42+Wbi5K7Z7Zo2u9nALvdVB+5789k2Z2y02Gou8QC X7QCzZyoBkKRf/Bo9PA5hor/K0cZYzuop/O0e0Kfu0f8LNnmJp2scP4z0T+xOG9kGTRMXDZX2yb9d /0rGioV1hT+BqhVuMRwo3WLN01NGAd0GIosX/z3iqhAVkaMHm9LupaktW4YiPG+xaEd5CCG73hxIo yUpO15TezAQlD/YgIJtsBahGHOZtuXj0ojNmaN78t3en9HynvbZGSx0C61M3a31q2o+C3Qow75lyx stdhLEptlt92CCMRoaCA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qGlFS-00E3r9-2h; Tue, 04 Jul 2023 18:59:38 +0000 Received: from out-51.mta1.migadu.com ([2001:41d0:203:375::33]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qGlFO-00E3px-39 for linux-arm-kernel@lists.infradead.org; Tue, 04 Jul 2023 18:59:36 +0000 Date: Tue, 4 Jul 2023 11:54:02 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1688496837; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=2Y4FgZXJ7x48QVp6BHNp316Cs4N1KcNcIDsf4Li1btE=; b=F1u6d6f2WKhnSqYxFVGE4mrYo0dson7wThHf0ZPAwwzD16L2MumyX6ZZazSkFglX5Ej8Vp Cn9WFZWkmrUIpunzBDWlECe/I7W9TCNkdq18uObpgucVFdBVwCz6AcW/orr7tIsNQJmGlG hKSf0NJstc/Odcx6iAETtcJ7VxLMGGw= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Kristina Martsenko Cc: Marc Zyngier , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, James Morse , Suzuki K Poulose , Zenghui Yu , isaku.yamahata@intel.com, seanjc@google.com, pbonzini@redhat.com, stable@vger.kernek.org Subject: Re: [PATCH] KVM: arm64: Disable preemption in kvm_arch_hardware_enable() Message-ID: References: <20230703163548.1498943-1-maz@kernel.org> <4c92ceb6-34a2-3128-9b26-dd58e4d7612a@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4c92ceb6-34a2-3128-9b26-dd58e4d7612a@arm.com> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230704_115935_160063_828268D7 X-CRM114-Status: GOOD ( 17.79 ) 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="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jul 04, 2023 at 07:32:09PM +0100, Kristina Martsenko wrote: > On 03/07/2023 17:35, Marc Zyngier wrote: > > Since 0bf50497f03b ("KVM: Drop kvm_count_lock and instead protect > > kvm_usage_count with kvm_lock"), hotplugging back a CPU whilst > > a guest is running results in a number of ugly splats as most > > of this code expects to run with preemption disabled, which isn't > > the case anymore. > > > > While the context is preemptable, it isn't migratable, which should > > be enough. But we have plenty of preemptible() checks all over > > the place, and our per-CPU accessors also disable preemption. > > > > Since this affects released versions, let's do the easy fix first, > > disabling preemption in kvm_arch_hardware_enable(). We can always > > revisit this with a more invasive fix in the future. > > > > Fixes: 0bf50497f03b ("KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock") > > Reported-by: Kristina Martsenko > > Tested-by: Kristina Martsenko > > Signed-off-by: Marc Zyngier > > Link: https://lore.kernel.org/r/aeab7562-2d39-e78e-93b1-4711f8cc3fa5@arm.com > > Cc: stable@vger.kernek.org # v6.3, v6.4 > > Typo here, didn't make it to the stable list (kernek.org -> kernel.org) Thanks for catching this Kristina, I'll fix it up when I apply the patch. So long as the patch appears in Linus' tree with the correct Cc it'll find its way to the stable trees. -- Thanks, Oliver _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel