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=-13.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 1110CC432BE for ; Mon, 26 Jul 2021 15:14:48 +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 B611460249 for ; Mon, 26 Jul 2021 15:14:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org B611460249 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=jlekstrand.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E88DD6EC2A; Mon, 26 Jul 2021 15:14:45 +0000 (UTC) Received: from mail-yb1-xb30.google.com (mail-yb1-xb30.google.com [IPv6:2607:f8b0:4864:20::b30]) by gabe.freedesktop.org (Postfix) with ESMTPS id DAC8B6EB9C for ; Mon, 26 Jul 2021 15:14:44 +0000 (UTC) Received: by mail-yb1-xb30.google.com with SMTP id x192so15447981ybe.0 for ; Mon, 26 Jul 2021 08:14:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jlekstrand-net.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=jifQRgGL6BJnh2QHxNCgt5ahwpxhb+ayyK8E8mUw8ys=; b=B+PXj7s3DgXdxAobXGNksbTi122W3r9yny4USm536JCHCcuNREuqaxp3S3vSZw4S4k 14nUhp1SyPZ/G5sgaOSKgXhqLScIqx2GDd9YEHAY9lIuGkzxm6W/q9ytt44UikJMZqvn 1Eg7ALax9R4oCl0dhdCEgxQ8zd2Ggm+zIqyRu4tFmfd1xlTTT0iutEnzXDcVKlUCSzow n7v3fIIAKlyQvl4lE5NB51xL42GBsPpSR3f+iG2GI5SFSEaLfnchCU1ZT1r/PEL8TC7P tHDY7xchWuh+OTOdir50vUIEzUCuL9Ra0zd6MCcnPosDvM3CF+fbWXIplN1VgJjnofe/ fywA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=jifQRgGL6BJnh2QHxNCgt5ahwpxhb+ayyK8E8mUw8ys=; b=sjY1SKf05/KCZd/X+GFYVHB9AuvP+gSviwGNktmKkRVI8Uoa4ER3/et89p94wrKR7V 44mTB6J8hjVanrpE8B85Ti4992jmAWhLSLDHnHIKea2Tlnt69jvgAq5UKRM4+JUkeGqe 4w+s8f/6NkB50qv/cGD2KhG/ogR9hal/Ga7AAIrzNHHzX3ZvGmfBqYSNBSlvpPMHn/li 3rKGEzk/GyjSOr9mQAs4spBa9pMK/KvGfouHAoTCWqYIpHHr6+4VmWqnNp73BVmEl6+H R6ddNzMOQ49F9NrPuFrP3Kn9NRTgbC6cJyPtdF3YFrkCrxaYBvKr+nHZhA9SbixRW/ld I2+A== X-Gm-Message-State: AOAM531vYExWplvQbnSpKvYbqjkj1VFWcSsjZ+Skxs7Q1QaklMEKipda RgVZlfENRiN98tqx+RPTG0waqkp8Sw1TfMMam4BJ7A== X-Google-Smtp-Source: ABdhPJwKW13ai9/QuQoz523Eo9tHb46TXlmLoiSEh7VOL2y0i8sTSD/vJFcvbT2dw0Cz/bAbix3IisAadTiMVNsmVkE= X-Received: by 2002:a25:208b:: with SMTP id g133mr23935540ybg.211.1627312483937; Mon, 26 Jul 2021 08:14:43 -0700 (PDT) MIME-Version: 1.0 References: <20210723113405.427004-1-matthew.auld@intel.com> <0988bf67-c42a-1e7e-af77-ae2da65b036f@linux.intel.com> In-Reply-To: <0988bf67-c42a-1e7e-af77-ae2da65b036f@linux.intel.com> From: Jason Ekstrand Date: Mon, 26 Jul 2021 10:14:32 -0500 Message-ID: Subject: Re: [PATCH] drm/i915/userptr: Probe existence of backing struct pages upon creation To: Maarten Lankhorst Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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: =?UTF-8?Q?Thomas_Hellstr=C3=B6m?= , Tvrtko Ursulin , Jordan Justen , Intel GFX , Tvrtko Ursulin , Maling list - DRI developers , Chris Wilson , Kenneth Graunke , Matthew Auld , Daniel Vetter Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, Jul 26, 2021 at 3:31 AM Maarten Lankhorst wrote: > > Op 23-07-2021 om 13:34 schreef Matthew Auld: > > From: Chris Wilson > > > > Jason Ekstrand requested a more efficient method than userptr+set-domai= n > > to determine if the userptr object was backed by a complete set of page= s > > upon creation. To be more efficient than simply populating the userptr > > using get_user_pages() (as done by the call to set-domain or execbuf), > > we can walk the tree of vm_area_struct and check for gaps or vma not > > backed by struct page (VM_PFNMAP). The question is how to handle > > VM_MIXEDMAP which may be either struct page or pfn backed... > > > > With discrete we are going to drop support for set_domain(), so offerin= g > > a way to probe the pages, without having to resort to dummy batches has > > been requested. > > > > v2: > > - add new query param for the PROBE flag, so userspace can easily > > check if the kernel supports it(Jason). > > - use mmap_read_{lock, unlock}. > > - add some kernel-doc. > > v3: > > - In the docs also mention that PROBE doesn't guarantee that the pages > > will remain valid by the time they are actually used(Tvrtko). > > - Add a small comment for the hole finding logic(Jason). > > - Move the param next to all the other params which just return true. > > > > Testcase: igt/gem_userptr_blits/probe > > Signed-off-by: Chris Wilson > > Signed-off-by: Matthew Auld > > Cc: Thomas Hellstr=C3=B6m > > Cc: Maarten Lankhorst > > Cc: Tvrtko Ursulin > > Cc: Jordan Justen > > Cc: Kenneth Graunke > > Cc: Jason Ekstrand > > Cc: Daniel Vetter > > Cc: Ramalingam C > > Reviewed-by: Tvrtko Ursulin > > Acked-by: Kenneth Graunke > > Reviewed-by: Jason Ekstrand > > --- > > drivers/gpu/drm/i915/gem/i915_gem_userptr.c | 41 ++++++++++++++++++++- > > drivers/gpu/drm/i915/i915_getparam.c | 1 + > > include/uapi/drm/i915_drm.h | 20 ++++++++++ > > 3 files changed, 61 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/= drm/i915/gem/i915_gem_userptr.c > > index 56edfeff8c02..468a7a617fbf 100644 > > --- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c > > @@ -422,6 +422,34 @@ static const struct drm_i915_gem_object_ops i915_g= em_userptr_ops =3D { > > > > #endif > > > > +static int > > +probe_range(struct mm_struct *mm, unsigned long addr, unsigned long le= n) > > +{ > > + const unsigned long end =3D addr + len; > > + struct vm_area_struct *vma; > > + int ret =3D -EFAULT; > > + > > + mmap_read_lock(mm); > > + for (vma =3D find_vma(mm, addr); vma; vma =3D vma->vm_next) { > > + /* Check for holes, note that we also update the addr bel= ow */ > > + if (vma->vm_start > addr) > > + break; > > + > > + if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) > > + break; > > + > > + if (vma->vm_end >=3D end) { > > + ret =3D 0; > > + break; > > + } > > + > > + addr =3D vma->vm_end; > > + } > > + mmap_read_unlock(mm); > > + > > + return ret; > > +} > > + > > /* > > * Creates a new mm object that wraps some normal memory from the proc= ess > > * context - user memory. > > @@ -477,7 +505,8 @@ i915_gem_userptr_ioctl(struct drm_device *dev, > > } > > > > if (args->flags & ~(I915_USERPTR_READ_ONLY | > > - I915_USERPTR_UNSYNCHRONIZED)) > > + I915_USERPTR_UNSYNCHRONIZED | > > + I915_USERPTR_PROBE)) > > return -EINVAL; > > > > if (i915_gem_object_size_2big(args->user_size)) > > @@ -504,6 +533,16 @@ i915_gem_userptr_ioctl(struct drm_device *dev, > > return -ENODEV; > > } > > > > + if (args->flags & I915_USERPTR_PROBE) { > > + /* > > + * Check that the range pointed to represents real struct > > + * pages and not iomappings (at this moment in time!) > > + */ > > + ret =3D probe_range(current->mm, args->user_ptr, args->us= er_size); > > + if (ret) > > + return ret; > > + } > > + > > #ifdef CONFIG_MMU_NOTIFIER > > obj =3D i915_gem_object_alloc(); > > if (obj =3D=3D NULL) > > diff --git a/drivers/gpu/drm/i915/i915_getparam.c b/drivers/gpu/drm/i91= 5/i915_getparam.c > > index 24e18219eb50..bbb7cac43eb4 100644 > > --- a/drivers/gpu/drm/i915/i915_getparam.c > > +++ b/drivers/gpu/drm/i915/i915_getparam.c > > @@ -134,6 +134,7 @@ int i915_getparam_ioctl(struct drm_device *dev, voi= d *data, > > case I915_PARAM_HAS_EXEC_FENCE_ARRAY: > > case I915_PARAM_HAS_EXEC_SUBMIT_FENCE: > > case I915_PARAM_HAS_EXEC_TIMELINE_FENCES: > > + case I915_PARAM_HAS_USERPTR_PROBE: > > /* For the time being all of these are always true; > > * if some supported hardware does not have one of these > > * features this value needs to be provided from > > diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h > > index 975087553ea0..0d290535a6e5 100644 > > --- a/include/uapi/drm/i915_drm.h > > +++ b/include/uapi/drm/i915_drm.h > > @@ -674,6 +674,9 @@ typedef struct drm_i915_irq_wait { > > */ > > #define I915_PARAM_HAS_EXEC_TIMELINE_FENCES 55 > > > > +/* Query if the kernel supports the I915_USERPTR_PROBE flag. */ > > +#define I915_PARAM_HAS_USERPTR_PROBE 56 > > + > > /* Must be kept compact -- no holes and well documented */ > > > > typedef struct drm_i915_getparam { > > @@ -2222,12 +2225,29 @@ struct drm_i915_gem_userptr { > > * through the GTT. If the HW can't support readonly access, an e= rror is > > * returned. > > * > > + * I915_USERPTR_PROBE: > > + * > > + * Probe the provided @user_ptr range and validate that the @user= _ptr is > > + * indeed pointing to normal memory and that the range is also va= lid. > > + * For example if some garbage address is given to the kernel, th= en this > > + * should complain. > > + * > > + * Returns -EFAULT if the probe failed. > > + * > > + * Note that this doesn't populate the backing pages, and also do= esn't > > + * guarantee that the object will remain valid when the object is > > + * eventually used. > > + * > > + * The kernel supports this feature if I915_PARAM_HAS_USERPTR_PRO= BE > > + * returns a non-zero value. > > + * > > * I915_USERPTR_UNSYNCHRONIZED: > > * > > * NOT USED. Setting this flag will result in an error. > > */ > > __u32 flags; > > #define I915_USERPTR_READ_ONLY 0x1 > > +#define I915_USERPTR_PROBE 0x2 > > #define I915_USERPTR_UNSYNCHRONIZED 0x80000000 > > /** > > * @handle: Returned handle for the object. > > Could we use _VALIDATE instead of probe? Or at least pin the pages as wel= l, so we don't have to do it later? I only care that the name matches what it does. _VALIDATE sounds like it does a full validation of everything such that, if the import succeeds, execbuf will as well. If we pin the pages at the same time, maybe that's true? _PROBE, on the other hand, sounds a lot more like a one-time best-effort check which may race with other stuff and doesn't guarantee future success. That's in line with what the current patch does. > We already have i915_gem_object_userptr_validate, no need to dupe it. I have no opinion on this. --Jason