From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) (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 887F079F4 for ; Wed, 24 Jul 2024 01:13:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.187 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721783615; cv=none; b=K/G59EQ5VTJxbk4ePM26XZaEYI0eKdGI9CHh0P+oeFivgn0YAOj4l5zYxkMx/M92THpNmmDmNe8lO1ivoOxyxRI0zPVmu/6SOmUafQyDDnpbx1NBrcLv0jUr15ZAfOEpqEgCtt2gb3HuNzRRd0jdzf3mal+Kxm6aVluHQQgcsnI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721783615; c=relaxed/simple; bh=80F5/mvdOoU0DZ/ovoR6d5ECFxd7w/YJPhKB4rqGRR8=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=jClzvHfyCCFQ6G0AO+5915A0a53O/NZmyaW2sgdZ0zTce+o+QxQ2WmVFULr/PlTYp73q6HITbxuzxO3YmcWGVu8GnC/RSxtu50/Ff4M2Z/MzJMxvaHUywZVnj5nEsWVfrnyPorGKhzJGY3/3Zb9Xyg6uAFcas634IX+aAiyEgSw= 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=45.249.212.187 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 szxga01-in.huawei.com (SkyGuard) with ESMTP id 4WTGHC4LcrzxTwR; Wed, 24 Jul 2024 09:13:27 +0800 (CST) Received: from kwepemd200012.china.huawei.com (unknown [7.221.188.145]) by mail.maildlp.com (Postfix) with ESMTPS id 6D2CD1800A2; Wed, 24 Jul 2024 09:13:29 +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; Wed, 24 Jul 2024 09:13:28 +0800 Message-ID: Date: Wed, 24 Jul 2024 09:13:27 +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> <4b05e4fe-0906-102f-5697-eec7ee222bef@hisilicon.com> <86bk2o2drs.wl-maz@kernel.org> From: Zhou Wang In-Reply-To: <86bk2o2drs.wl-maz@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemd200012.china.huawei.com (7.221.188.145) On 2024/7/24 1:56, Marc Zyngier wrote: > On Tue, 23 Jul 2024 02:51:32 +0100, > Zhou Wang wrote: >> >> 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. > > Great, thanks for giving it a go. I have just posted an actual patch > (with the exact same change) at [1]. It would be good if you could > give it a Tested-by: tag. Sure, I will give it a Tested-by. Thanks, Zhou > > Thanks, > > M. > > [1] https://lore.kernel.org/r/20240723175203.3193882-1-maz@kernel.org >