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 6B88418C3B; Mon, 17 Jun 2024 15:13:45 +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=1718637227; cv=none; b=Ix2Pt36d+Nmtm0UFyK465HSfuadjx7ZJEC0Hzg7D8Fy638dlKugpdO1KI9lwgTZhYOhZdKvm6XVWrq719HoKeT28ac5wtqZwRy4fYzVBZXamXyDOQVO7I6ytzxsaR/5MIC9zQ7I8lruD73t2zKx7b69h0SSbo21BVnW3UBGvLlc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718637227; c=relaxed/simple; bh=UL43jVAhdU+OtHdX5bK5r64Vwn48uow1EiUNHTwDAzw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=DiUTWUPcxhIYTu2V/ECrQyAfwUBjSoA2i+R1c5YPEN0ZFEHNKKxFmT0Hg0HdmLP49blynUH3wSh9S2LI6a9G0yZr10dKc6IhG7oKPWilcEnHKJ61pLkBlBWdzid8tqRHExxcXHHlAy+EMD5uIBZ5yABiradNCieK5cXoMAVZjCc= 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 7D46EDA7; Mon, 17 Jun 2024 08:14:09 -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 D132E3F6A8; Mon, 17 Jun 2024 08:13:42 -0700 (PDT) Message-ID: <85f5250f-0d50-4aa3-93c9-2008c6ccb8fb@arm.com> Date: Mon, 17 Jun 2024 16:13:41 +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 v4 1/2] iommu/io-pgtable-arm: Add way to debug pgtable walk To: Rob Clark , Will Deacon Cc: linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, Rob Clark , Joerg Roedel , Jason Gunthorpe , Boris Brezillon , Kevin Tian , Joao Martins , "moderated list:ARM SMMU DRIVERS" , "open list:IOMMU SUBSYSTEM" , open list , dri-devel@lists.freedesktop.org References: <20240523175227.117984-1-robdclark@gmail.com> <20240523175227.117984-2-robdclark@gmail.com> From: Robin Murphy Content-Language: en-GB In-Reply-To: <20240523175227.117984-2-robdclark@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 23/05/2024 6:52 pm, Rob Clark wrote: > From: Rob Clark > > Add an io-pgtable method to walk the pgtable returning the raw PTEs that > would be traversed for a given iova access. Have to say I'm a little torn here - with my iommu-dma hat on I'm not super enthusiastic about adding any more overhead to iova_to_phys, but in terms of maintaining io-pgtable I do like the overall shape of the implementation... Will, how much would you hate a compromise of inlining iova_to_phys as the default walk behaviour if cb is NULL? :) That said, looking at the unmap figures for dma_map_benchmark on a Neoverse N1, any difference I think I see is still well within the noise, so maybe a handful of extra indirect calls isn't really enough to worry about? Cheers, Robin. > Signed-off-by: Rob Clark > --- > drivers/iommu/io-pgtable-arm.c | 51 ++++++++++++++++++++++++++++------ > include/linux/io-pgtable.h | 4 +++ > 2 files changed, 46 insertions(+), 9 deletions(-) > > diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c > index f7828a7aad41..f47a0e64bb35 100644 > --- a/drivers/iommu/io-pgtable-arm.c > +++ b/drivers/iommu/io-pgtable-arm.c > @@ -693,17 +693,19 @@ static size_t arm_lpae_unmap_pages(struct io_pgtable_ops *ops, unsigned long iov > data->start_level, ptep); > } > > -static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops, > - unsigned long iova) > +static int arm_lpae_pgtable_walk(struct io_pgtable_ops *ops, unsigned long iova, > + int (*cb)(void *cb_data, void *pte, int level), > + void *cb_data) > { > struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops); > arm_lpae_iopte pte, *ptep = data->pgd; > int lvl = data->start_level; > + int ret; > > do { > /* Valid IOPTE pointer? */ > if (!ptep) > - return 0; > + return -EFAULT; > > /* Grab the IOPTE we're interested in */ > ptep += ARM_LPAE_LVL_IDX(iova, lvl, data); > @@ -711,22 +713,52 @@ static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops, > > /* Valid entry? */ > if (!pte) > - return 0; > + return -EFAULT; > + > + ret = cb(cb_data, &pte, lvl); > + if (ret) > + return ret; > > - /* Leaf entry? */ > + /* Leaf entry? If so, we've found the translation */ > if (iopte_leaf(pte, lvl, data->iop.fmt)) > - goto found_translation; > + return 0; > > /* Take it to the next level */ > ptep = iopte_deref(pte, data); > } while (++lvl < ARM_LPAE_MAX_LEVELS); > > /* Ran out of page tables to walk */ > + return -EFAULT; > +} > + > +struct iova_to_phys_walk_data { > + arm_lpae_iopte pte; > + int level; > +}; > + > +static int iova_to_phys_walk_cb(void *cb_data, void *pte, int level) > +{ > + struct iova_to_phys_walk_data *d = cb_data; > + > + d->pte = *(arm_lpae_iopte *)pte; > + d->level = level; > + > return 0; > +} > + > +static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops, > + unsigned long iova) > +{ > + struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops); > + struct iova_to_phys_walk_data d; > + int ret; > + > + ret = arm_lpae_pgtable_walk(ops, iova, iova_to_phys_walk_cb, &d); > + if (ret) > + return 0; > > -found_translation: > - iova &= (ARM_LPAE_BLOCK_SIZE(lvl, data) - 1); > - return iopte_to_paddr(pte, data) | iova; > + iova &= (ARM_LPAE_BLOCK_SIZE(d.level, data) - 1); > + return iopte_to_paddr(d.pte, data) | iova; > } > > static void arm_lpae_restrict_pgsizes(struct io_pgtable_cfg *cfg) > @@ -807,6 +839,7 @@ arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg) > .map_pages = arm_lpae_map_pages, > .unmap_pages = arm_lpae_unmap_pages, > .iova_to_phys = arm_lpae_iova_to_phys, > + .pgtable_walk = arm_lpae_pgtable_walk, > }; > > return data; > diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h > index 86cf1f7ae389..261b48af068a 100644 > --- a/include/linux/io-pgtable.h > +++ b/include/linux/io-pgtable.h > @@ -177,6 +177,7 @@ struct io_pgtable_cfg { > * @map_pages: Map a physically contiguous range of pages of the same size. > * @unmap_pages: Unmap a range of virtually contiguous pages of the same size. > * @iova_to_phys: Translate iova to physical address. > + * @pgtable_walk: (optional) Perform a page table walk for a given iova. > * > * These functions map directly onto the iommu_ops member functions with > * the same names. > @@ -190,6 +191,9 @@ struct io_pgtable_ops { > struct iommu_iotlb_gather *gather); > phys_addr_t (*iova_to_phys)(struct io_pgtable_ops *ops, > unsigned long iova); > + int (*pgtable_walk)(struct io_pgtable_ops *ops, unsigned long iova, > + int (*cb)(void *cb_data, void *pte, int level), > + void *cb_data); > int (*read_and_clear_dirty)(struct io_pgtable_ops *ops, > unsigned long iova, size_t size, > unsigned long flags,