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 4F0FCC02194 for ; Fri, 7 Feb 2025 18:14:38 +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:Content-Type:MIME-Version: References:In-Reply-To:Subject:Cc:To:From:Message-ID: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=iJyg4sI0QyId4oE7ZRfE0Ib9s22gU7dFzyU94n/SzG4=; b=coHGMH8CgPDmqV4HacuBjdySPh sR2L4xBA6Y0sAwc9zTQYZViTssPP3EuDk6xYL9a0vMvaCNrGCIDWPu4DZpfRNcbt9TSnYawDy6dRg bPa8DdN4b38ETNmu2y4SA4DgT0geq28uyPPVfJzd+uJq2OHYgb/8GCjeuQbejfW9glsnymrlhZkms NN6K7WduV9dm8jCAFYaC2rw1ztypJUo9s/Ogw1S9f0/6DyBZaUNsbYOZQe4pcrWPB9wUu/VtUaMGZ DJm5PKoyXy7Oj6/FhLCPhWx0+dsuBYnixxjGa6+/ufT2iSgehA556y2WPdSKjyzkctC+BiRHxoV0i rb/MLUXA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tgSs1-0000000AeEo-1VXq; Fri, 07 Feb 2025 18:14:29 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tgSoX-0000000AdUa-1ajd for linux-arm-kernel@lists.infradead.org; Fri, 07 Feb 2025 18:10:54 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 04BA35C70D8; Fri, 7 Feb 2025 18:10:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 419ADC4CEDF; Fri, 7 Feb 2025 18:10:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1738951852; bh=MlvBE2BowHXDWbwjymFqCoSazPaseEcDREg8QI4ix3U=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=qcg2Wqooswd9VWz+nlJX5lAmqZv/x7OO/B5x6jJRT9Jb+QygFwyFIPSd1XDOmRqQl ZRkrqW9KbTiZnh73FeDCDHPUyiXXZGm/wmpFlpvofRdY4+OitfDVkOdRnj0UOweZrw nNJMyKM0Gt1EDuUnRcFRutAfIwHdg9xQk7SAZZxUc6PjqKOVfbuB4M/QVcJic/y7VV wuKZcbLDWRIPQ8Gl+HeY473+fU52En0MYZ1JSK+7qUITgYHQpeySpRjBOQdm8+a4aW Xx9PsmPKWhwlYGAnuSRHIXH1ws9llqzC1k0WkbCC/z3fJPQdTze9YfZUkEh25MyGQF nf2uyxNP9rHpg== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1tgSoT-001jk8-S4; Fri, 07 Feb 2025 18:10:50 +0000 Date: Fri, 07 Feb 2025 18:10:49 +0000 Message-ID: <86ed09tyl2.wl-maz@kernel.org> From: Marc Zyngier To: Oliver Upton Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, Alexander Potapenko , Joey Gouly , Suzuki K Poulose , Zenghui Yu Subject: Re: [PATCH 0/3] KVM: arm64: Assorted vgic fixes for 6.14 In-Reply-To: References: <20250206152100.1107909-1-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.4 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: oliver.upton@linux.dev, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, glider@google.com, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250207_101053_461409_E14E7028 X-CRM114-Status: GOOD ( 22.91 ) 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 Fri, 07 Feb 2025 18:03:55 +0000, Oliver Upton wrote: > > On Thu, Feb 06, 2025 at 03:20:57PM +0000, Marc Zyngier wrote: > > Alexander, while fuzzing KVM/arm64, found an annoying set of problems, > > all stemming from the fact that the vgic can be destroyed in parallel > > with the rest of the guest still being live. > > > > Yes, this is annoying. > > > > Fixing this is not going to happen overnight (though I have some > > ideas), but we can make what we have today a bit more robust. > > > > This is what patch #2 is doing. Patch #1 is just removing a loud > > WARN_ON() that serves little purpose, and patch #3 fixes the actual > > bug that Alex reported. > > > > Hopefully, none of that is controversial... > > I'm a bit grumbly about slapping bandaids on the problem, but given the > fact that glider reported all of this a while ago and we still haven't > fixed it is enough to justify these patches. So: Yeah, same here. I'm starting to think that we need to either prevent the vgic from being asynchronously destroyed, or start refcounting all IRQs just like LPIs. Which is very annoying since we don't have a global namespace for SGIs and PPIs. But maybe simply refcounting the vgic itself would be enough. Thoughts? > Reviewed-by: Oliver Upton Thanks, M. -- Without deviation from the norm, progress is not possible.