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 DAB8E8286A for ; Wed, 2 Oct 2024 23:05:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727910355; cv=none; b=jqNta5NZBoYXiCHMe6dDA/4wAXpRiJdMBakVZ9Z3I1MxamYKtw8LUe5Ph+COKRGM+3QPiQA1FJIOeMaxwTFRmblJ+SOXAzVSP2S302k6KL/T/ckOl1lUpSMmoszVO+yIpOLwLEwTxAJsP7xI90HqYE65FgyeVNEEJuPDJU3ixZk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727910355; c=relaxed/simple; bh=aEi6ljH26Pp0QoVP8PRqq40SVqz37BtId5MQjjzmsaA=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=DzyKFN1E6e6dw324hL+/K1IaN4CBu9BKKlWu7K4kJQCzF2nkeFHmxwklUPKVWuGyTOpWkFTBQ8TxnfqiKIWzV1G0EjxMhq+XY+u0vurVeUwfLQZbjinxT/jD7ohbCPuils151Sg8XBzyxPAZndhD8/67YRPyLnoapFYabIUu9hg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KKQ8jWNa; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KKQ8jWNa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76251C4CEC2; Wed, 2 Oct 2024 23:05:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727910355; bh=aEi6ljH26Pp0QoVP8PRqq40SVqz37BtId5MQjjzmsaA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=KKQ8jWNacwtIKIfmG45Mu79UWakIhs9/1gIylZV//D18dsgYxHuOH/m5MS8TpsHVn RblMUuvdTVHkWIovJOYzW4JOtmCd6QI1F1RqHdSd2gzdauUxTEdkeOIqDWAgX0gNTC WyIXclgcJTH8VsyZp8mFzjWJlca/yHVAnb5ovmYypnFrZw+PEeMfoNIXxSkO4gTMNd 05JHiifhe3lSVrcFEIrN8CGQQjLDHmYdWZPnZ3vQ5DIKxQ3ZacAdSBNkfoYkE2Kasj /N0+qjXXymvg0jtZ1jIgcfvcwoYRLYEcZ98EbbEPjDAp6OnanYlGGQFL8Yxr1ejatf fTr6hybsiq/xA== 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 1sw8Pp-00HBcU-9N; Thu, 03 Oct 2024 00:05:53 +0100 Date: Thu, 03 Oct 2024 00:05:52 +0100 Message-ID: <867caq6r73.wl-maz@kernel.org> From: Marc Zyngier To: Thomas Gleixner Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Kunkun Jiang Subject: Re: [PATCH] irqchip/gic-v4: Don't allow a VMOVP on a dying VPE In-Reply-To: <87zfnmup41.ffs@tglx> References: <20241002204959.2051709-1-maz@kernel.org> <87zfnmup41.ffs@tglx> 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) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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: tglx@linutronix.de, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, jiangkunkun@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Wed, 02 Oct 2024 23:17:02 +0100, Thomas Gleixner wrote: > > On Wed, Oct 02 2024 at 21:49, Marc Zyngier wrote: > > Kunkun Jiang reports that there is a small window of opportunity for > > userspace to force a change of affinity for a VPE while the VPE has > > already been unmapped, but the corresponding doorbell interrupt still > > visible in /proc/irq/. > > > > Plug the race by checking the value of vmapp_count, which tracks whether > > the VPE is mapped ot not, and returning an error in this case. > > > > This involves making vmapp_count common to both GICv4.1 and its v4.0 > > ancestor. > > > > Reported-by: Kunkun Jiang > > Signed-off-by: Marc Zyngier > > Link: https://lore.kernel.org/r/c182ece6-2ba0-ce4f-3404-dba7a3ab6c52@huawei.com > > I assume this wants a Fixes: tag and a cc: stable, no? Unclear. While this is clearly a bug, the architectural effects are not fatal, and nothing goes really wrong. However, some implementations are reporting this as a RAS error. That's a bit silly, because this isn't indicative of HW rotting away, and only a sure way to shoot yourself in the foot. That's the real bug IMO. So if these people are really hung up on having this addressed in prehistoric kernels, we can always add: Fixes: 64edfaa9a234 ("irqchip/gic-v4.1: Implement the v4.1 flavour of VMAPP") which points to the commit that implements the infrastructure we're relying on. GICv4.0, which predates the above by at least a couple of years is also affected, but nobody really cares about that. Thanks, M. -- Without deviation from the norm, progress is not possible.