From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) (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 2A96CEC2 for ; Tue, 23 Jul 2024 01:51:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721699498; cv=none; b=lVrpbnT6nvBSa6m2prNxTY+AFGKFbxf8Rx8mSsA7bXAiBIhURhXbbCDpzvb0ovq+MG/5qSsXLm08UvdI3Rdn2vXbO6Pi4aS7uMynwfJxah0JZO6hsBn4ywkCUevpFs24h5Z7yOztH6pKQBDh7H5kgeuRCuFFZoYJr/3a+K3XKz8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721699498; c=relaxed/simple; bh=jUrkGwSO66LnwEsMthFz4Gr+3TKnWcWun6e2quTSna0=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=mBA8tX7z2HMzY5LqnSVSgRmQNp5boKVFMjH3bpb0K+5nLgZ0TVxYsMtq2wepu8nn5PAtBCLpBp8x9HM3noOJIzh8cxMf5E0D8YE1KDlrJ0jCcEA5ZBHSwvNavt0i+RsQ4AzWCF0qdHoMqn+NOY0jfNcIp7DhVWvnWieLXgqEB6o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=hisilicon.com; spf=pass smtp.mailfrom=hisilicon.com; arc=none smtp.client-ip=45.249.212.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=hisilicon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=hisilicon.com Received: from mail.maildlp.com (unknown [172.19.163.252]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4WSg7b4mXpzdjrP; Tue, 23 Jul 2024 09:49:47 +0800 (CST) Received: from kwepemd200012.china.huawei.com (unknown [7.221.188.145]) by mail.maildlp.com (Postfix) with ESMTPS id 1F71118009D; Tue, 23 Jul 2024 09:51:34 +0800 (CST) Received: from [10.67.121.115] (10.67.121.115) by kwepemd200012.china.huawei.com (7.221.188.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.34; Tue, 23 Jul 2024 09:51:33 +0800 Message-ID: <4b05e4fe-0906-102f-5697-eec7ee222bef@hisilicon.com> Date: Tue, 23 Jul 2024 09:51:32 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH 3/3] irqchip/gic-v4: Make sure a VPE is locked when VMAPP is issued Content-Language: en-US To: Marc Zyngier CC: , , , Thomas Gleixner , Nianyao Tang References: <20240705093155.871070-1-maz@kernel.org> <20240705093155.871070-4-maz@kernel.org> <2c9489cc-d276-7c52-5d52-7f234fdc726e@hisilicon.com> <86h6cl39ff.wl-maz@kernel.org> From: Zhou Wang In-Reply-To: <86h6cl39ff.wl-maz@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemd200012.china.huawei.com (7.221.188.145) On 2024/7/19 19:31, Marc Zyngier wrote: > On Fri, 19 Jul 2024 10:42:02 +0100, > Zhou Wang wrote: >> >> On 2024/7/5 17:31, Marc Zyngier wrote: >>> In order to make sure that vpe->col_idx is correctly sampled >>> when a VMAPP command is issued, we must hold the lock for the >>> VPE. This is now possible since the introduction of the per-VM >>> vmapp_lock, which can be taken before vpe_lock in the locking >>> order. >>> >>> Signed-off-by: Marc Zyngier >>> --- >>> drivers/irqchip/irq-gic-v3-its.c | 8 ++++++-- >>> 1 file changed, 6 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c >>> index b52d60097cad5..951ec140bcea2 100644 >>> --- a/drivers/irqchip/irq-gic-v3-its.c >>> +++ b/drivers/irqchip/irq-gic-v3-its.c >>> @@ -1810,7 +1810,9 @@ static void its_map_vm(struct its_node *its, struct its_vm *vm) >>> for (i = 0; i < vm->nr_vpes; i++) { >>> struct its_vpe *vpe = vm->vpes[i]; >>> >>> - its_send_vmapp(its, vpe, true); >>> + scoped_guard(raw_spinlock, &vpe->vpe_lock) >>> + its_send_vmapp(its, vpe, true); >>> + >>> its_send_vinvall(its, vpe); >>> } >>> } >>> @@ -1827,8 +1829,10 @@ static void its_unmap_vm(struct its_node *its, struct its_vm *vm) >>> if (!--vm->vlpi_count[its->list_nr]) { >>> int i; >>> >>> - for (i = 0; i < vm->nr_vpes; i++) >>> + for (i = 0; i < vm->nr_vpes; i++) { >>> + guard(raw_spinlock)(&vm->vpes[i]->vpe_lock); >>> its_send_vmapp(its, vm->vpes[i], false); >>> + } >>> } >>> } >>> >> >> Hi Marc, >> >> It looks like there is ABBA deadlock after applying this series: >> >> In its_map_vm: vmapp_lock -> vpe_lock >> In its_vpe_set_affinity: vpe_to_cpuid_lock(vpe_lock) -> its_send_vmovp(vmapp_lock) >> >> Any idea about this? > > Hmmm, well spotted. That's an annoying one. > > Can you give the below hack a go? I've only lightly tested it, as my > D05 box is on its last leg (it is literally falling apart) and I don't > have any other GICv4.x box to test on. > > Thanks, > > M. > > diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c > index 951ec140bcea2..b88c6011c8771 100644 > --- a/drivers/irqchip/irq-gic-v3-its.c > +++ b/drivers/irqchip/irq-gic-v3-its.c > @@ -1328,12 +1328,6 @@ static void its_send_vmovp(struct its_vpe *vpe) > return; > } > > - /* > - * Protect against concurrent updates of the mapping state on > - * individual VMs. > - */ > - guard(raw_spinlock_irqsave)(&vpe->its_vm->vmapp_lock); > - > /* > * Yet another marvel of the architecture. If using the > * its_list "feature", we need to make sure that all ITSs > @@ -3808,7 +3802,7 @@ static int its_vpe_set_affinity(struct irq_data *d, > struct its_vpe *vpe = irq_data_get_irq_chip_data(d); > unsigned int from, cpu = nr_cpu_ids; > struct cpumask *table_mask; > - unsigned long flags; > + unsigned long flags, vmapp_flags; > > /* > * Changing affinity is mega expensive, so let's be as lazy as > @@ -3822,7 +3816,14 @@ static int its_vpe_set_affinity(struct irq_data *d, > * protect us, and that we must ensure nobody samples vpe->col_idx > * during the update, hence the lock below which must also be > * taken on any vLPI handling path that evaluates vpe->col_idx. > + * > + * Finally, we must protect ourselves against concurrent > + * updates of the mapping state on this VM should the ITS list > + * be in use. > */ > + if (its_list_map) > + raw_spin_lock_irqsave(&vpe->its_vm->vmapp_lock, vmapp_flags); > + > from = vpe_to_cpuid_lock(vpe, &flags); > table_mask = gic_data_rdist_cpu(from)->vpe_table_mask; > > @@ -3852,6 +3853,9 @@ static int its_vpe_set_affinity(struct irq_data *d, > irq_data_update_effective_affinity(d, cpumask_of(cpu)); > vpe_to_cpuid_unlock(vpe, flags); > > + if (its_list_map) > + raw_spin_unlock_irqrestore(&vpe->its_vm->vmapp_lock, vmapp_flags); > + > return IRQ_SET_MASK_OK_DONE; > } > Hi Marc， We add above code to do test again. Now it is OK. Bests, Zhou >