Re: [PATCH 0/5] Optimize iommu_map_sg() performance

From: isaacm@codeaurora.org
To: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Cc: will@kernel.org, pdaly@codeaurora.org, robin.murphy@arm.com,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	pratikp@codeaurora.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/5] Optimize iommu_map_sg() performance
Date: Mon, 11 Jan 2021 07:12:42 -0800	[thread overview]
Message-ID: <6f57460f1b95373c615fdbad97edd9ed@codeaurora.org> (raw)
In-Reply-To: <5a29b6e339c66e9c7cd9a608baa3f9e1@codeaurora.org>

On 2021-01-10 23:52, Sai Prakash Ranjan wrote:
> On 2021-01-11 11:52, Sai Prakash Ranjan wrote:
>> Hi Isaac,
>> 
>> I gave this series a go on chromebook and saw these warnings
>> and several device probe failures, logs attached below:
>> 
>> WARN corresponds to this code in arm_lpae_map_by_pgsize()
>> 
>> 	if (WARN_ON(iaext || (paddr + size) >> cfg->oas))
>> 		return -ERANGE;
>> 
>> Logs:
>> 
>> [    2.411391] ------------[ cut here ]------------
>> [    2.416149] WARNING: CPU: 6 PID: 56 at
>> drivers/iommu/io-pgtable-arm.c:492 arm_lpae_map_sg+0x234/0x248
>> [    2.425606] Modules linked in:
>> [    2.428749] CPU: 6 PID: 56 Comm: kworker/6:1 Not tainted 5.10.5 
>> #970
>> [    2.440287] Workqueue: events deferred_probe_work_func
>> [    2.445563] pstate: 20c00009 (nzCv daif +PAN +UAO -TCO BTYPE=--)
>> [    2.451726] pc : arm_lpae_map_sg+0x234/0x248
>> [    2.456112] lr : arm_lpae_map_sg+0xe0/0x248
>> [    2.460410] sp : ffffffc010513750
>> [    2.463820] x29: ffffffc010513790 x28: ffffffb943332000
>> [    2.469281] x27: 0000000ffffff000 x26: ffffffb943d14900
>> [    2.474738] x25: 0000000000001000 x24: 0000000103465000
>> [    2.480196] x23: 0000000000000001 x22: 0000000103466000
>> [    2.485645] x21: 0000000000000003 x20: 0000000000000a20
>> [    2.491103] x19: ffffffc010513850 x18: 0000000000000001
>> [    2.496562] x17: 0000000000000002 x16: 00000000ffffffff
>> [    2.502021] x15: 0000000000000000 x14: 0000000000000000
>> [    2.507479] x13: 0000000000000001 x12: 0000000000000000
>> [    2.512928] x11: 0000001000000000 x10: 0000000000000000
>> [    2.518385] x9 : 0000000000000001 x8 : 0000000040201000
>> [    2.523844] x7 : 0000000000000a20 x6 : ffffffb943463000
>> [    2.529302] x5 : 0000000000000003 x4 : 0000000000001000
>> [    2.534760] x3 : 0000000000000001 x2 : ffffffb941f605a0
>> [    2.540219] x1 : 0000000000000003 x0 : 0000000000000e40
>> [    2.545679] Call trace:
>> [    2.548196]  arm_lpae_map_sg+0x234/0x248
>> [    2.552225]  arm_smmu_map_sg+0x80/0xc4
>> [    2.556078]  __iommu_map_sg+0x6c/0x188
>> [    2.559931]  iommu_map_sg_atomic+0x18/0x20
>> [    2.564144]  iommu_dma_alloc_remap+0x26c/0x34c
>> [    2.568703]  iommu_dma_alloc+0x9c/0x268
>> [    2.572647]  dma_alloc_attrs+0x88/0xfc
>> [    2.576503]  gsi_ring_alloc+0x50/0x144
>> [    2.580356]  gsi_init+0x2c4/0x5c4
>> [    2.583766]  ipa_probe+0x14c/0x2b4
>> [    2.587263]  platform_drv_probe+0x94/0xb4
>> [    2.591377]  really_probe+0x138/0x348
>> [    2.595145]  driver_probe_device+0x80/0xb8
>> [    2.599358]  __device_attach_driver+0x90/0xa8
>> [    2.603829]  bus_for_each_drv+0x84/0xcc
>> [    2.607772]  __device_attach+0xc0/0x148
>> [    2.611713]  device_initial_probe+0x18/0x20
>> [    2.616012]  bus_probe_device+0x38/0x94
>> [    2.619953]  deferred_probe_work_func+0x78/0xb0
>> [    2.624611]  process_one_work+0x210/0x3dc
>> [    2.628726]  worker_thread+0x284/0x3e0
>> [    2.632578]  kthread+0x148/0x1a8
>> [    2.635891]  ret_from_fork+0x10/0x18
>> [    2.639562] ---[ end trace 9bac18cad6a9862e ]---
>> [    2.644414] ipa 1e40000.ipa: error -12 allocating channel 0 event 
>> ring
>> [    2.651656] ipa: probe of 1e40000.ipa failed with error -12
>> [    2.660072] dwc3 a600000.dwc3: Adding to iommu group 8
>> [    2.668632] xhci-hcd xhci-hcd.13.auto: xHCI Host Controller
>> [    2.674680] xhci-hcd xhci-hcd.13.auto: new USB bus registered,
>> assigned bus number 1
>> 
> 
> <snip>...
> 
> Isaac provided a fix which he will post as v2 and no warnings were 
> observed
> with that fix.
> 
> Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
> 
> Thanks,
> Sai

Thanks for testing out the patches. I've added the fix (there was an 
off-by-one error in the calculation
used to check if the IOVA/physical addresses are within limits) to 
version 2 of the series:
https://lore.kernel.org/linux-iommu/1610376862-927-1-git-send-email-isaacm@codeaurora.org/T/#t

Thanks,
Isaac
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