From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9BF3C4363A for ; Fri, 30 Oct 2020 14:17:44 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8BA632076E for ; Fri, 30 Oct 2020 14:17:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8BA632076E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sigxcpu.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7FC976EDDA; Fri, 30 Oct 2020 14:17:42 +0000 (UTC) Received: from honk.sigxcpu.org (honk.sigxcpu.org [24.134.29.49]) by gabe.freedesktop.org (Postfix) with ESMTPS id 150196EDDA; Fri, 30 Oct 2020 14:17:41 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by honk.sigxcpu.org (Postfix) with ESMTP id 8EFCDFB03; Fri, 30 Oct 2020 15:17:38 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at honk.sigxcpu.org Received: from honk.sigxcpu.org ([127.0.0.1]) by localhost (honk.sigxcpu.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 5RT3Dr6ncZMs; Fri, 30 Oct 2020 15:17:36 +0100 (CET) Received: by bogon.sigxcpu.org (Postfix, from userid 1000) id 103304463D; Fri, 30 Oct 2020 15:17:35 +0100 (CET) Date: Fri, 30 Oct 2020 15:17:35 +0100 From: Guido =?iso-8859-1?Q?G=FCnther?= To: Lucas Stach Subject: Re: [RFC PATCH 2/2] drm: etnaviv: Unmap gems on gem_close Message-ID: <20201030141735.GA62306@bogon.m.sigxcpu.org> References: <8a354530944e6a606212fe537c689ec20422a954.camel@pengutronix.de> <20201029182054.GC401619@phenom.ffwll.local> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: David Airlie , etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Russell King Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi, On Fri, Oct 30, 2020 at 10:19:54AM +0100, Lucas Stach wrote: > Am Donnerstag, den 29.10.2020, 19:20 +0100 schrieb Daniel Vetter: > > On Thu, Oct 29, 2020 at 03:38:21PM +0100, Lucas Stach wrote: > > > Hi Guido, > > > = > > > Am Donnerstag, den 29.10.2020, 15:20 +0100 schrieb Guido G=FCnther: > > > > So far the unmap from gpu address space only happened when dropping= the > > > > last ref in gem_free_object_unlocked, however that is skipped if th= ere's > > > > still multiple handles to the same GEM object. > > > > = > > > > Since userspace (here mesa) in the case of softpin hands back the m= emory > > > > region to the pool of available GPU virtual memory closing the hand= le > > > > via DRM_IOCTL_GEM_CLOSE this can lead to etnaviv_iommu_insert_exact > > > > failing later since userspace thinks the vaddr is available while t= he > > > > kernel thinks it isn't making the submit fail like > > > > = > > > > [E] submit failed: -14 (No space left on device) (etna_cmd_stream= _flush:244) > > > > = > > > > Fix this by unmapping the memory via the .gem_close_object callback. > > > > = > > > > Signed-off-by: Guido G=FCnther > > > > --- > > > > drivers/gpu/drm/etnaviv/etnaviv_drv.c | 1 + > > > > drivers/gpu/drm/etnaviv/etnaviv_drv.h | 1 + > > > > drivers/gpu/drm/etnaviv/etnaviv_gem.c | 32 +++++++++++++++++++++++= ++++ > > > > 3 files changed, 34 insertions(+) > > > > = > > > > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/dr= m/etnaviv/etnaviv_drv.c > > > > index a9a3afaef9a1..fdcc6405068c 100644 > > > > --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c > > > > +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c > > > > @@ -491,6 +491,7 @@ static struct drm_driver etnaviv_drm_driver =3D= { > > > > .open =3D etnaviv_open, > > > > .postclose =3D etnaviv_postclose, > > > > .gem_free_object_unlocked =3D etnaviv_gem_free_object, > > > > + .gem_close_object =3D etnaviv_gem_close_object, > > > > .gem_vm_ops =3D &vm_ops, > > > > .prime_handle_to_fd =3D drm_gem_prime_handle_to_fd, > > > > .prime_fd_to_handle =3D drm_gem_prime_fd_to_handle, > > > > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.h b/drivers/gpu/dr= m/etnaviv/etnaviv_drv.h > > > > index 4d8dc9236e5f..2226a9af0d63 100644 > > > > --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.h > > > > +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.h > > > > @@ -65,6 +65,7 @@ int etnaviv_gem_cpu_prep(struct drm_gem_object *o= bj, u32 op, > > > > struct drm_etnaviv_timespec *timeout); > > > > int etnaviv_gem_cpu_fini(struct drm_gem_object *obj); > > > > void etnaviv_gem_free_object(struct drm_gem_object *obj); > > > > +void etnaviv_gem_close_object(struct drm_gem_object *obj, struct d= rm_file *file); > > > > int etnaviv_gem_new_handle(struct drm_device *dev, struct drm_file= *file, > > > > u32 size, u32 flags, u32 *handle); > > > > int etnaviv_gem_new_userptr(struct drm_device *dev, struct drm_fil= e *file, > > > > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/dr= m/etnaviv/etnaviv_gem.c > > > > index f06e19e7be04..5aec4a23c77e 100644 > > > > --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c > > > > +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c > > > > @@ -515,6 +515,38 @@ static const struct etnaviv_gem_ops etnaviv_ge= m_shmem_ops =3D { > > > > .mmap =3D etnaviv_gem_mmap_obj, > > > > }; > > > > = > > > > +void etnaviv_gem_close_object(struct drm_gem_object *obj, struct d= rm_file *unused) > > > > +{ > > > > + struct etnaviv_gem_object *etnaviv_obj =3D to_etnaviv_bo(obj); > > > > + struct etnaviv_vram_mapping *mapping, *tmp; > > > > + > > > > + /* Handle this via etnaviv_gem_free_object */ > > > > + if (obj->handle_count =3D=3D 1) > > > > + return; > > > > + > > > > + WARN_ON(is_active(etnaviv_obj)); > > > > + > > > > + /* > > > > + * userspace wants to release the handle so we need to remove > > > > + * the mapping from the gpu's virtual address space to stay > > > > + * in sync. > > > > + */ > > > > + list_for_each_entry_safe(mapping, tmp, &etnaviv_obj->vram_list, > > > > + obj_node) { > > > > + struct etnaviv_iommu_context *context =3D mapping->context; > > > > + > > > > + WARN_ON(mapping->use); > > > > + > > > > + if (context) { > > > > + etnaviv_iommu_unmap_gem(context, mapping); > > > > + etnaviv_iommu_context_put(context); > > > = > > > I see the issue you are trying to fix here, but this is not a viable > > > fix. While userspace may close the handle, the GPU may still be > > > processing jobs referening the BO, so we can't just unmap it from the > > > address space. > > > = > > > I think what we need to do here is waiting for the current jobs/fences > > > of the BO when we hit the case where userspace tries to assign a new > > > address to the BO. Basically wait for current jobs -> unamp from the > > > address space -> map at new userspace assigned address. > > = > > Yeah was about to say the same. There's two solutions to this: > > - let the kernel manage the VA space. This is what amdgpu does in some > > cases (but still no relocations) > > - pipeline the VA/PTE updates in your driver, because userspace has a > > somewhat hard time figuring out when a buffer is done. Doing that wou= ld > > either at complexity or stalls when the kernel is doing all the track= ing > > already anyway. Minimal fix is to do what Lucas explained above, but > > importantly with the kernel solution we have the option to fully > > pipeline everything and avoid stalls. I think this is what everyone e= lse > > who lets userspace manage VA does in their kernel side. > = > I thought a bit more about this and the issue is only about userspace > reusing regions of its _private_ address space, before they are GPU > inactive. So the problem of tracking BO active for figuring out when it > is safe to close the handle (and thus forget about the last placement > of the BO in the AS) goes from "is this BO globally active anywhere?" > to "is this BO still active in one of the jobs I submitted?", which is > not hard at all for the userspace to figure out. It's about private address space, yes. = > With this in mind I think we can reasonably declare the kernel behavior > of rejecting the submit as okay and just add the tiny bit of userspace > fencing needed for the userspace driver to not close the handle until > the last submit referencing this BO has finished. Sounds reasonable, i'll have a look. Cheers, -- Guido > = > Regards, > Lucas > = _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel