[PATCH v2 06/10] iommu/rockchip: Convert to generic_single_device_group()

[Marek Szyprowski]

Hi Jason,

On 31.07.2023 19:50, Jason Gunthorpe wrote:
> Use the new helper.
>
> Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
> ---
>   drivers/iommu/rockchip-iommu.c | 22 ++--------------------
>   1 file changed, 2 insertions(+), 20 deletions(-)

After applying your recent fixes from "[PATCH 0/3] Fix device_lock 
deadlock on two probe() paths" thread I've decided to run more tests on 
all boards I have. This way I found that this patch breaks booting of 
Odroid-M1 board, which is ARM64 system based on Rockchip RK3568 
(arch/arm64/boot/dts/rockchip/rk3568-odroid-m1.dts). Here is the log:

Unable to handle kernel NULL pointer dereference at virtual address 
0000000000000028
Mem abort info:
...
Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
Modules linked in: hantro_vpu(+) crct10dif_ce rockchip_saradc v4l2_vp9 
industrialio_triggered_buffer v4l2_h264 kfifo_buf display_connector 
dwmac_rk(+) v4l2_mem2mem snd_soc_simple_card stmmac_platform 
videobuf2_dma_contig snd_soc_simple_card_utils videobuf2_memops 
rockchip_thermal videobuf2_v4l2 stmmac videodev pcs_xpcs 
snd_soc_rockchip_i2s_tdm videobuf2_common rtc_rk808 mc panfrost 
rockchipdrm drm_shmem_helper gpu_sched analogix_dp dw_mipi_dsi dw_hdmi 
drm_display_helper ip_tables x_tables ipv6
CPU: 2 PID: 147 Comm: systemd-udevd Not tainted 6.5.0-rc1+ #13826
Hardware name: Hardkernel ODROID-M1 (DT)
pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : generic_single_device_group+0x24/0x88
lr : generic_single_device_group+0x5c/0x88
...
Call trace:
  generic_single_device_group+0x24/0x88
  __iommu_probe_device+0xe8/0x444
  iommu_probe_device+0x1c/0x54
  of_iommu_configure+0x10c/0x200
  of_dma_configure_id+0x1e0/0x3b4
  platform_dma_configure+0x30/0x78
  really_probe+0x70/0x2b4
  __driver_probe_device+0x78/0x12c
  driver_probe_device+0x3c/0x160
  __driver_attach+0x9c/0x1ac
  bus_for_each_dev+0x74/0xd4
  driver_attach+0x24/0x30
  bus_add_driver+0xe4/0x1e8
  driver_register+0x60/0x128
  __platform_driver_register+0x28/0x34
  hantro_driver_init+0x20/0x1000 [hantro_vpu]
  do_one_initcall+0x74/0x2f0
  do_init_module+0x58/0x1ec
  load_module+0x1a20/0x1c64
  init_module_from_file+0x84/0xc0
  idempotent_init_module+0x180/0x250
  __arm64_sys_finit_module+0x64/0xa0
  invoke_syscall+0x48/0x114
  el0_svc_common.constprop.0+0xec/0x10c
  do_el0_svc+0x38/0xa4
  el0_svc+0x40/0xac
  el0t_64_sync_handler+0xc0/0xc4
  el0t_64_sync+0x190/0x194
---[ end trace 0000000000000000 ]---

It turns out that iommu pointer gathered from dev->iommu->iommu_dev is 
NULL in generic_single_device_group() in the above call stack. Reverting 
$subject on top of linux-next+"[PATCH 0/3] Fix device_lock deadlock on 
two probe() paths" fixes booting.


> diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
> index 8ff69fbf9f65db..91f13cc9411548 100644
> --- a/drivers/iommu/rockchip-iommu.c
> +++ b/drivers/iommu/rockchip-iommu.c
> @@ -113,7 +113,6 @@ struct rk_iommu {
>   	struct iommu_device iommu;
>   	struct list_head node; /* entry in rk_iommu_domain.iommus */
>   	struct iommu_domain *domain; /* domain to which iommu is attached */
> -	struct iommu_group *group;
>   };
>   
>   struct rk_iommudata {
> @@ -1155,15 +1154,6 @@ static void rk_iommu_release_device(struct device *dev)
>   	device_link_del(data->link);
>   }
>   
> -static struct iommu_group *rk_iommu_device_group(struct device *dev)
> -{
> -	struct rk_iommu *iommu;
> -
> -	iommu = rk_iommu_from_dev(dev);
> -
> -	return iommu_group_ref_get(iommu->group);
> -}
> -
>   static int rk_iommu_of_xlate(struct device *dev,
>   			     struct of_phandle_args *args)
>   {
> @@ -1189,7 +1179,7 @@ static const struct iommu_ops rk_iommu_ops = {
>   	.domain_alloc = rk_iommu_domain_alloc,
>   	.probe_device = rk_iommu_probe_device,
>   	.release_device = rk_iommu_release_device,
> -	.device_group = rk_iommu_device_group,
> +	.device_group = generic_single_device_group,
>   #ifdef CONFIG_ARM
>   	.set_platform_dma_ops = rk_iommu_set_platform_dma,
>   #endif
> @@ -1280,15 +1270,9 @@ static int rk_iommu_probe(struct platform_device *pdev)
>   	if (err)
>   		return err;
>   
> -	iommu->group = iommu_group_alloc();
> -	if (IS_ERR(iommu->group)) {
> -		err = PTR_ERR(iommu->group);
> -		goto err_unprepare_clocks;
> -	}
> -
>   	err = iommu_device_sysfs_add(&iommu->iommu, dev, NULL, dev_name(dev));
>   	if (err)
> -		goto err_put_group;
> +		goto err_unprepare_clocks;
>   
>   	err = iommu_device_register(&iommu->iommu, &rk_iommu_ops, dev);
>   	if (err)
> @@ -1325,8 +1309,6 @@ static int rk_iommu_probe(struct platform_device *pdev)
>   	pm_runtime_disable(dev);
>   err_remove_sysfs:
>   	iommu_device_sysfs_remove(&iommu->iommu);
> -err_put_group:
> -	iommu_group_put(iommu->group);
>   err_unprepare_clocks:
>   	clk_bulk_unprepare(iommu->num_clocks, iommu->clocks);
>   	return err;

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland