From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4124E29CB44; Tue, 29 Apr 2025 12:38:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745930336; cv=none; b=X5iMeuY1L5u6b3nJoFa5AZ22w/5jW4BiFT8PgVj0maznm/emuks6YG/zDQ7wXC0VvSW7x2DHdQPgHzB5m8ajZroVe/r63ZH2w1axuO/xUxDGftDfkWXhPSlasr3KqZNY98HddOE5HF6GEAoW+/UEFh2vXJo3ufXp+oq2AP3P4JY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745930336; c=relaxed/simple; bh=CpR7EqqVdeCUa/1aKeOMIAoY9nTzrtK99SFVjukk8iQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=P+muLDQHKFoGl0pneb9bOms4rO+swfCTiCDAF8xBJBo52lLrChZ8SQmiNXxTrQYzzmmS7UPklStX2Ms+tc6X4OWizSzQ3LZZS44GjefEEmJ6njeRZnAa4B2OGJE2+pGqS8eatz7vvdp7QCSxdrs4TQrQ158yExBQUn2OaJmJyWM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9CFAA1515; Tue, 29 Apr 2025 05:38:47 -0700 (PDT) Received: from [10.1.196.40] (e121345-lin.cambridge.arm.com [10.1.196.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A6D213F66E; Tue, 29 Apr 2025 05:38:52 -0700 (PDT) Message-ID: <2e074d63-ad0c-47fa-aeb0-cb03c81829fe@arm.com> Date: Tue, 29 Apr 2025 13:38:51 +0100 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 03/33] iommu/io-pgtable-arm: Add quirk to quiet WARN_ON() To: Rob Clark , dri-devel@lists.freedesktop.org Cc: freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, Connor Abbott , Rob Clark , Will Deacon , Joerg Roedel , Jason Gunthorpe , Nicolin Chen , Kevin Tian , Joao Martins , "moderated list:ARM SMMU DRIVERS" , "open list:IOMMU SUBSYSTEM" , open list References: <20250428205619.227835-1-robdclark@gmail.com> <20250428205619.227835-4-robdclark@gmail.com> From: Robin Murphy Content-Language: en-GB In-Reply-To: <20250428205619.227835-4-robdclark@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 28/04/2025 9:54 pm, Rob Clark wrote: > From: Rob Clark > > In situations where mapping/unmapping squence can be controlled by > userspace, attempting to map over a region that has not yet been > unmapped is an error. But not something that should spam dmesg. > > Signed-off-by: Rob Clark > --- > drivers/iommu/io-pgtable-arm.c | 18 ++++++++++++------ > include/linux/io-pgtable.h | 8 ++++++++ > 2 files changed, 20 insertions(+), 6 deletions(-) > > diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c > index f27965caf6a1..99523505dac5 100644 > --- a/drivers/iommu/io-pgtable-arm.c > +++ b/drivers/iommu/io-pgtable-arm.c > @@ -475,7 +475,7 @@ static int __arm_lpae_map(struct arm_lpae_io_pgtable *data, unsigned long iova, > cptep = iopte_deref(pte, data); > } else if (pte) { > /* We require an unmap first */ > - WARN_ON(!selftest_running); > + WARN_ON(!selftest_running && !(cfg->quirks & IO_PGTABLE_QUIRK_NO_WARN_ON)); If we are going to have this as a general mechanism then the selftests should use it as well. Thanks, Robin. > return -EEXIST; > } > > @@ -649,8 +649,10 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data, > unmap_idx_start = ARM_LPAE_LVL_IDX(iova, lvl, data); > ptep += unmap_idx_start; > pte = READ_ONCE(*ptep); > - if (WARN_ON(!pte)) > - return 0; > + if (!pte) { > + WARN_ON(!(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NO_WARN_ON)); > + return -ENOENT; > + } > > /* If the size matches this level, we're in the right place */ > if (size == ARM_LPAE_BLOCK_SIZE(lvl, data)) { > @@ -660,8 +662,10 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data, > /* Find and handle non-leaf entries */ > for (i = 0; i < num_entries; i++) { > pte = READ_ONCE(ptep[i]); > - if (WARN_ON(!pte)) > + if (!pte) { > + WARN_ON(!(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NO_WARN_ON)); > break; > + } > > if (!iopte_leaf(pte, lvl, iop->fmt)) { > __arm_lpae_clear_pte(&ptep[i], &iop->cfg, 1); > @@ -976,7 +980,8 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie) > if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS | > IO_PGTABLE_QUIRK_ARM_TTBR1 | > IO_PGTABLE_QUIRK_ARM_OUTER_WBWA | > - IO_PGTABLE_QUIRK_ARM_HD)) > + IO_PGTABLE_QUIRK_ARM_HD | > + IO_PGTABLE_QUIRK_NO_WARN_ON)) > return NULL; > > data = arm_lpae_alloc_pgtable(cfg); > @@ -1079,7 +1084,8 @@ arm_64_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg, void *cookie) > struct arm_lpae_io_pgtable *data; > typeof(&cfg->arm_lpae_s2_cfg.vtcr) vtcr = &cfg->arm_lpae_s2_cfg.vtcr; > > - if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_S2FWB)) > + if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_S2FWB | > + IO_PGTABLE_QUIRK_NO_WARN_ON)) > return NULL; > > data = arm_lpae_alloc_pgtable(cfg); > diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h > index bba2a51c87d2..639b8f4fb87d 100644 > --- a/include/linux/io-pgtable.h > +++ b/include/linux/io-pgtable.h > @@ -88,6 +88,13 @@ struct io_pgtable_cfg { > * > * IO_PGTABLE_QUIRK_ARM_HD: Enables dirty tracking in stage 1 pagetable. > * IO_PGTABLE_QUIRK_ARM_S2FWB: Use the FWB format for the MemAttrs bits > + * > + * IO_PGTABLE_QUIRK_NO_WARN_ON: Do not WARN_ON() on conflicting > + * mappings, but silently return -EEXISTS. Normally an attempt > + * to map over an existing mapping would indicate some sort of > + * kernel bug, which would justify the WARN_ON(). But for GPU > + * drivers, this could be under control of userspace. Which > + * deserves an error return, but not to spam dmesg. > */ > #define IO_PGTABLE_QUIRK_ARM_NS BIT(0) > #define IO_PGTABLE_QUIRK_NO_PERMS BIT(1) > @@ -97,6 +104,7 @@ struct io_pgtable_cfg { > #define IO_PGTABLE_QUIRK_ARM_OUTER_WBWA BIT(6) > #define IO_PGTABLE_QUIRK_ARM_HD BIT(7) > #define IO_PGTABLE_QUIRK_ARM_S2FWB BIT(8) > + #define IO_PGTABLE_QUIRK_NO_WARN_ON BIT(9) > unsigned long quirks; > unsigned long pgsize_bitmap; > unsigned int ias;