On Mon, Jun 3, 2019 at 4:40 AM Rob Clark <robdclark@xxxxxxxxx> wrote: > > On Fri, May 10, 2019 at 7:35 AM Rob Clark <robdclark@xxxxxxxxx> wrote: > > > > On Tue, Dec 4, 2018 at 2:29 PM Rob Herring <robh+dt@xxxxxxxxxx> wrote: > > > > > > On Sat, Dec 1, 2018 at 10:54 AM Rob Clark <robdclark@xxxxxxxxx> wrote: > > > > > > > > This solves a problem we see with drm/msm, caused by getting > > > > iommu_dma_ops while we attach our own domain and manage it directly at > > > > the iommu API level: > > > > > > > > [0000000000000038] user address but active_mm is swapper > > > > Internal error: Oops: 96000005 [#1] PREEMPT SMP > > > > Modules linked in: > > > > CPU: 7 PID: 70 Comm: kworker/7:1 Tainted: G W 4.19.3 #90 > > > > Hardware name: xxx (DT) > > > > Workqueue: events deferred_probe_work_func > > > > pstate: 80c00009 (Nzcv daif +PAN +UAO) > > > > pc : iommu_dma_map_sg+0x7c/0x2c8 > > > > lr : iommu_dma_map_sg+0x40/0x2c8 > > > > sp : ffffff80095eb4f0 > > > > x29: ffffff80095eb4f0 x28: 0000000000000000 > > > > x27: ffffffc0f9431578 x26: 0000000000000000 > > > > x25: 00000000ffffffff x24: 0000000000000003 > > > > x23: 0000000000000001 x22: ffffffc0fa9ac010 > > > > x21: 0000000000000000 x20: ffffffc0fab40980 > > > > x19: ffffffc0fab40980 x18: 0000000000000003 > > > > x17: 00000000000001c4 x16: 0000000000000007 > > > > x15: 000000000000000e x14: ffffffffffffffff > > > > x13: ffff000000000000 x12: 0000000000000028 > > > > x11: 0101010101010101 x10: 7f7f7f7f7f7f7f7f > > > > x9 : 0000000000000000 x8 : ffffffc0fab409a0 > > > > x7 : 0000000000000000 x6 : 0000000000000002 > > > > x5 : 0000000100000000 x4 : 0000000000000000 > > > > x3 : 0000000000000001 x2 : 0000000000000002 > > > > x1 : ffffffc0f9431578 x0 : 0000000000000000 > > > > Process kworker/7:1 (pid: 70, stack limit = 0x0000000017d08ffb) > > > > Call trace: > > > > iommu_dma_map_sg+0x7c/0x2c8 > > > > __iommu_map_sg_attrs+0x70/0x84 > > > > get_pages+0x170/0x1e8 > > > > msm_gem_get_iova+0x8c/0x128 > > > > _msm_gem_kernel_new+0x6c/0xc8 > > > > msm_gem_kernel_new+0x4c/0x58 > > > > dsi_tx_buf_alloc_6g+0x4c/0x8c > > > > msm_dsi_host_modeset_init+0xc8/0x108 > > > > msm_dsi_modeset_init+0x54/0x18c > > > > _dpu_kms_drm_obj_init+0x430/0x474 > > > > dpu_kms_hw_init+0x5f8/0x6b4 > > > > msm_drm_bind+0x360/0x6c8 > > > > try_to_bring_up_master.part.7+0x28/0x70 > > > > component_master_add_with_match+0xe8/0x124 > > > > msm_pdev_probe+0x294/0x2b4 > > > > platform_drv_probe+0x58/0xa4 > > > > really_probe+0x150/0x294 > > > > driver_probe_device+0xac/0xe8 > > > > __device_attach_driver+0xa4/0xb4 > > > > bus_for_each_drv+0x98/0xc8 > > > > __device_attach+0xac/0x12c > > > > device_initial_probe+0x24/0x30 > > > > bus_probe_device+0x38/0x98 > > > > deferred_probe_work_func+0x78/0xa4 > > > > process_one_work+0x24c/0x3dc > > > > worker_thread+0x280/0x360 > > > > kthread+0x134/0x13c > > > > ret_from_fork+0x10/0x18 > > > > Code: d2800004 91000725 6b17039f 5400048a (f9401f40) > > > > ---[ end trace f22dda57f3648e2c ]--- > > > > Kernel panic - not syncing: Fatal exception > > > > SMP: stopping secondary CPUs > > > > Kernel Offset: disabled > > > > CPU features: 0x0,22802a18 > > > > Memory Limit: none > > > > > > > > The problem is that when drm/msm does it's own iommu_attach_device(), > > > > now the domain returned by iommu_get_domain_for_dev() is drm/msm's > > > > domain, and it doesn't have domain->iova_cookie. > > > > > > > > We kind of avoided this problem prior to sdm845/dpu because the iommu > > > > was attached to the mdp node in dt, which is a child of the toplevel > > > > mdss node (which corresponds to the dev passed in dma_map_sg()). But > > > > with sdm845, now the iommu is attached at the mdss level so we hit the > > > > iommu_dma_ops in dma_map_sg(). > > > > > > > > But auto allocating/attaching a domain before the driver is probed was > > > > already a blocking problem for enabling per-context pagetables for the > > > > GPU. This problem is also now solved with this patch. > > > > > > > > Fixes: 97890ba9289c dma-mapping: detect and configure IOMMU in of_dma_configure > > > > Tested-by: Douglas Anderson <dianders@xxxxxxxxxxxx> > > > > Signed-off-by: Rob Clark <robdclark@xxxxxxxxx> > > > > --- > > > > This is an alternative/replacement for [1]. What it lacks in elegance > > > > it makes up for in practicality ;-) > > > > > > > > [1] https://patchwork.freedesktop.org/patch/264930/ > > > > > > > > drivers/of/device.c | 22 ++++++++++++++++++++++ > > > > 1 file changed, 22 insertions(+) > > > > > > > > diff --git a/drivers/of/device.c b/drivers/of/device.c > > > > index 5957cd4fa262..15ffee00fb22 100644 > > > > --- a/drivers/of/device.c > > > > +++ b/drivers/of/device.c > > > > @@ -72,6 +72,14 @@ int of_device_add(struct platform_device *ofdev) > > > > return device_add(&ofdev->dev); > > > > } > > > > > > > > +static const struct of_device_id iommu_blacklist[] = { > > > > + { .compatible = "qcom,mdp4" }, > > > > + { .compatible = "qcom,mdss" }, > > > > + { .compatible = "qcom,sdm845-mdss" }, > > > > + { .compatible = "qcom,adreno" }, > > > > + {} > > > > +}; > > > > > > Not completely clear to whether this is still needed or not, but this > > > really won't scale. Why can't the driver for these devices override > > > whatever has been setup by default? > > > > > > > fwiw, at the moment it is not needed, but it will become needed again > > to implement per-context pagetables (although I suppose for this we > > only need to blacklist qcom,adreno and not also the display nodes). > > So, another case I've come across, on the display side.. I'm working > on handling the case where bootloader enables display (and takes iommu > out of reset).. as soon as DMA domain gets attached we get iommu > faults, because bootloader has already configured display for scanout. > Unfortunately this all happens before actual driver is probed and has > a chance to intervene. > > It's rather unfortunate that we tried to be clever rather than just > making drivers call some function to opt-in to the hookup of dma iommu > ops :-( I think it still works for the 90% of cases and if 10% needs some explicit work in the drivers, that's better than requiring 100% of the drivers to do things manually. Adding Marek who had the same problem on Exynos. Best regards, Tomasz > > BR, > -R > > > > > The reason is that in the current state the core code creates the > > first domain before the driver has a chance to intervene and tell it > > not to. And this results that driver ends up using a different > > context bank on the iommu than what the firmware expects. > > > > I guess the alternative is to put some property in DT.. but that > > doesn't really feel right. I guess there aren't really many (or any?) > > other drivers that have this specific problem, so I don't really > > expect it to be a scaling problem. > > > > Yeah, it's a bit ugly, but I'll take a small ugly working hack, over > > elegant but non-working any day ;-)... but if someone has a better > > idea then I'm all ears. > > > > BR, > > -R
