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Darwish" , Thomas Gleixner , Andy Shevchenko , Christoph Hellwig Subject: Re: [PATCH] drm/prime: Only call dma_map_sgtable() for devices with DMA support Message-ID: References: <20210219134014.7775-1-tzimmermann@suse.de> <79e272cb-b010-cb8d-57d3-71999164291a@tronnes.org> <823e5782-7dd0-d864-02b5-4c1e6edd0528@suse.de> <968e2131-18f3-e829-d098-89a98d3e73ea@tronnes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <968e2131-18f3-e829-d098-89a98d3e73ea@tronnes.org> X-Operating-System: Linux phenom 5.7.0-1-amd64 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, Feb 22, 2021 at 06:30:35PM +0100, Noralf Trønnes wrote: > > > Den 22.02.2021 08.54, skrev Thomas Zimmermann: > > Hi > > > > Am 20.02.21 um 14:02 schrieb Noralf Trønnes: > >> > >> > >> Den 19.02.2021 14.40, skrev Thomas Zimmermann: > >>> Fixes a regression for udl and probably other USB-based drivers where > >>> joining and mirroring displays fails. > >>> > >>> Joining displays requires importing a dma_buf from another DRM driver. > >>> These devices don't support DMA and therefore have no DMA mask. Trying > >>> to map imported buffers from a DMA-able memory zone fails with an error. > >>> An example is shown below. > >>> > >>> [   60.050199] ------------[ cut here ]------------ > >>> [   60.055092] WARNING: CPU: 0 PID: 1403 at kernel/dma/mapping.c:190 > >>> dma_map_sg_attrs+0x8f/0xc0 > >>> [   60.064331] Modules linked in: af_packet(E) rfkill(E) dmi_sysfs(E) > >>> intel_rapl_msr(E) intel_rapl_common(E) snd_hda_codec_realtek(E) > >>> snd_hda_codec_generic(E) ledtrig_audio(E) snd_hda_codec_hdmi(E) > >>> x86_pkg_temp_thermal(E) intel_powerclam) > >>> [   60.064801]  wmi(E) video(E) btrfs(E) blake2b_generic(E) > >>> libcrc32c(E) crc32c_intel(E) xor(E) raid6_pq(E) sg(E) dm_multipath(E) > >>> dm_mod(E) scsi_dh_rdac(E) scsi_dh_emc(E) scsi_dh_alua(E) msr(E) > >>> efivarfs(E) > >>> [   60.170778] CPU: 0 PID: 1403 Comm: Xorg.bin Tainted: G            > >>> E    5.11.0-rc5-1-default+ #747 > >>> [   60.179841] Hardware name: Dell Inc. OptiPlex 9020/0N4YC8, BIOS > >>> A24 10/24/2018 > >>> [   60.187145] RIP: 0010:dma_map_sg_attrs+0x8f/0xc0 > >>> [   60.191822] Code: 4d 85 ff 75 2b 49 89 d8 44 89 e1 44 89 f2 4c 89 > >>> ee 48 89 ef e8 62 30 00 00 85 c0 78 36 5b 5d 41 5c 41 5d 41 5e 41 5f > >>> c3 0f 0b <0f> 0b 31 c0 eb ed 49 8d 7f 50 e8 72 f5 2a 00 49 8b 47 50 > >>> 49 89 d8 > >>> [   60.210770] RSP: 0018:ffffc90001d6fc18 EFLAGS: 00010246 > >>> [   60.216062] RAX: 0000000000000000 RBX: 0000000000000020 RCX: > >>> ffffffffb31e677b > >>> [   60.223274] RDX: dffffc0000000000 RSI: ffff888212c10600 RDI: > >>> ffff8881b08a9488 > >>> [   60.230501] RBP: ffff8881b08a9030 R08: 0000000000000020 R09: > >>> ffff888212c10600 > >>> [   60.237710] R10: ffffed10425820df R11: 0000000000000001 R12: > >>> 0000000000000000 > >>> [   60.244939] R13: ffff888212c10600 R14: 0000000000000008 R15: > >>> 0000000000000000 > >>> [   60.252155] FS:  00007f08ac2b2f00(0000) GS:ffff8887cbe00000(0000) > >>> knlGS:0000000000000000 > >>> [   60.260333] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >>> [   60.266150] CR2: 000055831c899be8 CR3: 000000015372e006 CR4: > >>> 00000000001706f0 > >>> [   60.273369] Call Trace: > >>> [   60.275845]  drm_gem_map_dma_buf+0xb4/0x120 > >>> [   60.280089]  dma_buf_map_attachment+0x15d/0x1e0 > >>> [   60.284688]  drm_gem_prime_import_dev.part.0+0x5d/0x140 > >>> [   60.289984]  drm_gem_prime_fd_to_handle+0x213/0x280 > >>> [   60.294931]  ? drm_prime_destroy_file_private+0x30/0x30 > >>> [   60.300224]  drm_ioctl_kernel+0x131/0x180 > >>> [   60.304291]  ? drm_setversion+0x230/0x230 > >>> [   60.308366]  ? drm_prime_destroy_file_private+0x30/0x30 > >>> [   60.313659]  drm_ioctl+0x2f1/0x500 > >>> [   60.317118]  ? drm_version+0x150/0x150 > >>> [   60.320903]  ? lock_downgrade+0xa0/0xa0 > >>> [   60.324806]  ? do_vfs_ioctl+0x5f4/0x680 > >>> [   60.328694]  ? __fget_files+0x13e/0x210 > >>> [   60.332591]  ? ioctl_fiemap.isra.0+0x1a0/0x1a0 > >>> [   60.337102]  ? __fget_files+0x15d/0x210 > >>> [   60.340990]  __x64_sys_ioctl+0xb9/0xf0 > >>> [   60.344795]  do_syscall_64+0x33/0x80 > >>> [   60.348427]  entry_SYSCALL_64_after_hwframe+0x44/0xa9 > >> > >> I'm working on a USB display driver and got the same splat (although > >> from i915_gem_map_dma_buf) and silenced it using: > >> > >>     ret = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(64)); > >> > >> But I understand now that this is not the solution. > >> > >> Since the USB host controller can do DMA, would the following be an > >> acceptable solution? > > > > Not all controllers can do DMA AFAIK, so it's maybe not reliable. I'll > > send out another patch to address the issue later today. > > > > I looked at your other attempt at fixing this and the discussion about > how much work it is to fix this properly. > > For my use case I think I just won't support import on a USB controller > without DMA: > > if (!usb->bus->controller->dma_mask) > return -ENOSYS; > > A USB controller without DMA must be rare and I'll deal with that later > should the need arise. > > Thanks for bringing this issue to my attention. Yeah I think that's a reasonable short-term fix. Not perfect, but good enough for years most likely :-) -Daniel > > Noralf. > > > Best regards > > Thomas > > > >> > >> static struct drm_gem_object *gud_gem_prime_import(struct drm_device > >> *drm, struct dma_buf *dma_buf) > >> { > >>     struct usb_device *usb = gud_to_usb_device(to_gud_device(drm)); > >> > >>     drm_dbg_prime(drm, "usb->bus->controller=%s\n", > >> dev_name(usb->bus->controller)); > >> > >>     return drm_gem_prime_import_dev(drm, dma_buf, usb->bus->controller); > >> } > >> > >> static const struct drm_driver gud_drm_driver = { > >>     .gem_prime_import    = gud_gem_prime_import, > >> }; > >> > >> > >> Noralf. > >> > >>> [   60.353542] RIP: 0033:0x7f08ac7b53cb > >>> [   60.357168] Code: 89 d8 49 8d 3c 1c 48 f7 d8 49 39 c4 72 b5 e8 1c > >>> ff ff ff 85 c0 78 ba 4c 89 e0 5b 5d 41 5c c3 f3 0f 1e fa b8 10 00 00 > >>> 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 75 ba 0c 00 f7 d8 64 > >>> 89 01 48 > >>> [   60.376108] RSP: 002b:00007ffeabc89fc8 EFLAGS: 00000246 ORIG_RAX: > >>> 0000000000000010 > >>> [   60.383758] RAX: ffffffffffffffda RBX: 00007ffeabc8a00c RCX: > >>> 00007f08ac7b53cb > >>> [   60.390970] RDX: 00007ffeabc8a00c RSI: 00000000c00c642e RDI: > >>> 000000000000000d > >>> [   60.398221] RBP: 00000000c00c642e R08: 000055831c691d00 R09: > >>> 000055831b2ec010 > >>> [   60.405446] R10: 00007f08acf6ada0 R11: 0000000000000246 R12: > >>> 000055831c691d00 > >>> [   60.412667] R13: 000000000000000d R14: 00000000007e9000 R15: > >>> 0000000000000000 > >>> [   60.419903] irq event stamp: 672893 > >>> [   60.423441] hardirqs last  enabled at (672913): > >>> [] console_unlock+0x44d/0x500 > >>> [   60.432230] hardirqs last disabled at (672922): > >>> [] console_unlock+0x443/0x500 > >>> [   60.441021] softirqs last  enabled at (672940): > >>> [] __do_softirq+0x3dd/0x554 > >>> [   60.449634] softirqs last disabled at (672931): > >>> [] asm_call_irq_on_stack+0x12/0x20 > >>> [   60.458871] ---[ end trace f2f88696eb17806c ]--- > >>> > >>> For the fix, we don't call dma_map_sgtable() for devices without the > >>> DMA mask. Drivers for such devices have to map the imported buffer into > >>> kernel address space and perfom the copy operation in software. > >>> > >>> Tested by joining/mirroring displays of udl and radeon un der Gnome/X11. > >>> > >>> Signed-off-by: Thomas Zimmermann > >>> Fixes: 6eb0233ec2d0 ("usb: don't inherity DMA properties for USB > >>> devices") > >>> Cc: Christoph Hellwig > >>> Cc: Greg Kroah-Hartman > >>> Cc: Alan Stern > >>> Cc: Johan Hovold > >>> Cc: Andy Shevchenko > >>> Cc: Sebastian Andrzej Siewior > >>> Cc: "Ahmed S. Darwish" > >>> Cc: Mathias Nyman > >>> Cc: Oliver Neukum > >>> Cc: Felipe Balbi > >>> Cc: Thomas Gleixner > >>> Cc: # v5.10+ > >>> --- > >>>   drivers/gpu/drm/drm_prime.c | 27 ++++++++++++++++++--------- > >>>   1 file changed, 18 insertions(+), 9 deletions(-) > >>> > >>> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > >>> index 2a54f86856af..d5a39fe76b78 100644 > >>> --- a/drivers/gpu/drm/drm_prime.c > >>> +++ b/drivers/gpu/drm/drm_prime.c > >>> @@ -603,10 +603,15 @@ EXPORT_SYMBOL(drm_gem_map_detach); > >>>    * @attach: attachment whose scatterlist is to be returned > >>>    * @dir: direction of DMA transfer > >>>    * > >>> - * Calls &drm_gem_object_funcs.get_sg_table and then maps the > >>> scatterlist. This > >>> - * can be used as the &dma_buf_ops.map_dma_buf callback. Should be > >>> used together > >>> + * Calls &drm_gem_object_funcs.get_sg_table and, if possible, maps > >>> the scatterlist. > >>> + * This can be used as the &dma_buf_ops.map_dma_buf callback. Should > >>> be used together > >>>    * with drm_gem_unmap_dma_buf(). > >>>    * > >>> + * Devices on some peripheral busses, such as USB, cannot use DMA. > >>> In this case, > >>> + * pages in the scatterlist remain unmapped. Drivers for such > >>> devices should acquire > >>> + * a mapping with dma_buf_vmap() and implement copy operation via > >>> bus-specific > >>> + * interfaces. > >>> + * > >>>    * Returns:sg_table containing the scatterlist to be returned; > >>> returns ERR_PTR > >>>    * on error. May return -EINTR if it is interrupted by a signal. > >>>    */ > >>> @@ -627,12 +632,14 @@ struct sg_table *drm_gem_map_dma_buf(struct > >>> dma_buf_attachment *attach, > >>>       if (IS_ERR(sgt)) > >>>           return sgt; > >>> > >>> -    ret = dma_map_sgtable(attach->dev, sgt, dir, > >>> -                  DMA_ATTR_SKIP_CPU_SYNC); > >>> -    if (ret) { > >>> -        sg_free_table(sgt); > >>> -        kfree(sgt); > >>> -        sgt = ERR_PTR(ret); > >>> +    if (attach->dev->dma_mask) { > >>> +        ret = dma_map_sgtable(attach->dev, sgt, dir, > >>> +                      DMA_ATTR_SKIP_CPU_SYNC); > >>> +        if (ret) { > >>> +            sg_free_table(sgt); > >>> +            kfree(sgt); > >>> +            sgt = ERR_PTR(ret); > >>> +        } > >>>       } > >>> > >>>       return sgt; > >>> @@ -654,7 +661,9 @@ void drm_gem_unmap_dma_buf(struct > >>> dma_buf_attachment *attach, > >>>       if (!sgt) > >>>           return; > >>> > >>> -    dma_unmap_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC); > >>> +    if (attach->dev->dma_mask) > >>> +        dma_unmap_sgtable(attach->dev, sgt, dir, > >>> DMA_ATTR_SKIP_CPU_SYNC); > >>> + > >>>       sg_free_table(sgt); > >>>       kfree(sgt); > >>>   } > >>> -- > >>> 2.30.0 > >>> > >> _______________________________________________ > >> dri-devel mailing list > >> dri-devel@lists.freedesktop.org > >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > >> > > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch