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 BDC08748D; Wed, 7 May 2025 15:39:46 +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=1746632389; cv=none; b=RtJvGI1uJ7WhuxDQpDhUc5X3L3OfefVU94VQyjyAN64SYF/E3qlS03lcKUhK/3sFeVWf/81M+QdIyfPAMtgpRYQDXclmLt9VHcgi0vUweUxa4rjYDHzypTiWpnUiH86pOBQ8+axQ7mKkvMFkrrQlmDlJEhFaKuDvGnq0vqo+PBg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746632389; c=relaxed/simple; bh=tXA/bSYgzGq0C5DYDH2dfNVPwihtYXwbRIQh3juKr2k=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=d0S/nlhDu8AjQhHqL/lrMx918B5jTYM1AIeXSlrThgzN7fMm54n8aOTwRGNdFyg+xOQRQ8n2EmqbnxIosAJ0v2eIYYrIE5AdS8stoWWkNfO7M9buveMtf35SpBsaFURPi9p4qtUvmSjxoAqMhRwAguRKzMijF9VY8snbfJJCJrQ= 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 07344339; Wed, 7 May 2025 08:39:36 -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 76EA33F58B; Wed, 7 May 2025 08:39:44 -0700 (PDT) Message-ID: <0c5ce93a-c5ff-4b09-bde4-196da505cda2@arm.com> Date: Wed, 7 May 2025 16:39:43 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] iommu/io-pgtable-arm: Add quirk to quiet WARN_ON() To: Rob Clark , iommu@lists.linux.dev Cc: linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, Rob Clark , Will Deacon , Joerg Roedel , Jason Gunthorpe , Kevin Tian , Nicolin Chen , Joao Martins , "moderated list:ARM SMMU DRIVERS" , open list References: <20250507142953.269300-1-robdclark@gmail.com> From: Robin Murphy Content-Language: en-GB In-Reply-To: <20250507142953.269300-1-robdclark@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 07/05/2025 3:29 pm, Rob Clark wrote: > From: Rob Clark > > In situations where mapping/unmapping sequence 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. > > Now that there is a quirk, we can also drop the selftest_running > flag, and use the quirk instead for selftests. Acked-by: Robin Murphy > Signed-off-by: Rob Clark > --- > Sending v2 stand-alone, since I'm not quite ready to send a new > iteration of the full VM_BIND series. And with selftest_running > removed, I think this patch stands on it's own. (And maybe there > is still time to sneak this in for v6.16, removing an iommu dep > for the VM_BIND series in v6.17?) > > v2: Drop selftest_running and use IO_PGTABLE_QUIRK_NO_WARN_ON for > the selftests > > drivers/iommu/io-pgtable-arm.c | 27 ++++++++++++++------------- > include/linux/io-pgtable.h | 8 ++++++++ > 2 files changed, 22 insertions(+), 13 deletions(-) > > diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c > index f27965caf6a1..a535d88f8943 100644 > --- a/drivers/iommu/io-pgtable-arm.c > +++ b/drivers/iommu/io-pgtable-arm.c > @@ -253,8 +253,6 @@ static inline bool arm_lpae_concat_mandatory(struct io_pgtable_cfg *cfg, > (data->start_level == 1) && (oas == 40); > } > > -static bool selftest_running = false; > - > static dma_addr_t __arm_lpae_dma_addr(void *pages) > { > return (dma_addr_t)virt_to_phys(pages); > @@ -373,7 +371,7 @@ static int arm_lpae_init_pte(struct arm_lpae_io_pgtable *data, > for (i = 0; i < num_entries; i++) > if (iopte_leaf(ptep[i], lvl, data->iop.fmt)) { > /* We require an unmap first */ > - WARN_ON(!selftest_running); > + WARN_ON(!(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NO_WARN_ON)); > return -EEXIST; > } else if (iopte_type(ptep[i]) == ARM_LPAE_PTE_TYPE_TABLE) { > /* > @@ -475,7 +473,7 @@ 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(!(cfg->quirks & IO_PGTABLE_QUIRK_NO_WARN_ON)); > return -EEXIST; > } > > @@ -649,8 +647,10 @@ 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 +660,10 @@ 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 +978,8 @@ 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 +1082,8 @@ 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); > @@ -1320,7 +1324,6 @@ static void __init arm_lpae_dump_ops(struct io_pgtable_ops *ops) > #define __FAIL(ops, i) ({ \ > WARN(1, "selftest: test failed for fmt idx %d\n", (i)); \ > arm_lpae_dump_ops(ops); \ > - selftest_running = false; \ > -EFAULT; \ > }) > > @@ -1336,8 +1339,6 @@ static int __init arm_lpae_run_tests(struct io_pgtable_cfg *cfg) > size_t size, mapped; > struct io_pgtable_ops *ops; > > - selftest_running = true; > - > for (i = 0; i < ARRAY_SIZE(fmts); ++i) { > cfg_cookie = cfg; > ops = alloc_io_pgtable_ops(fmts[i], cfg, cfg); > @@ -1426,7 +1427,6 @@ static int __init arm_lpae_run_tests(struct io_pgtable_cfg *cfg) > free_io_pgtable_ops(ops); > } > > - selftest_running = false; > return 0; > } > > @@ -1448,6 +1448,7 @@ static int __init arm_lpae_do_selftests(void) > .tlb = &dummy_tlb_ops, > .coherent_walk = true, > .iommu_dev = &dev, > + .quirks = IO_PGTABLE_QUIRK_NO_WARN_ON, > }; > > /* __arm_lpae_alloc_pages() merely needs dev_to_node() to work */ > 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;