From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9A5BA4D8CE; Mon, 7 Jul 2025 19:01:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751914860; cv=none; b=EvyhFpRIZiN4Z8clRUzY2Z9lem5KonAaPD4gCl06UznsIHnYrk9VIbgy7Wa6dAOOlbEfpuL4Jj69s/SymeTmOMXmQMbZiCuBcfR5ugUzq4sABrK4pQZsWNM5tYZqwKPLrX2NoIsR1kv3CsoNancvOY01TCc01DEM+LFaHvA/7oc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751914860; c=relaxed/simple; bh=JrAruPZZICWqW2vK7DBmGDuymxQKXoE78qBV16PFDAE=; h=Mime-Version:Content-Type:Date:Message-Id:To:From:Subject:Cc: References:In-Reply-To; b=kRMLDNHReigRiC/bXIOK4ovP6seAum1iffn+0ToSbTQGfmIRB7B5UNvS9w60xTVmEPwKoW0S8DuH8kVLLhem9awh3pGEnEekB+7KlWOAAV5ZGLS6oSvekQUY/j643XMzbC5mUkebecKso+yvBIAknP7Vmh+sUWUmEKK0e53lYnY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Wd60hZX/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Wd60hZX/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 12F37C4CEE3; Mon, 7 Jul 2025 19:00:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751914860; bh=JrAruPZZICWqW2vK7DBmGDuymxQKXoE78qBV16PFDAE=; h=Date:To:From:Subject:Cc:References:In-Reply-To:From; b=Wd60hZX/n+mVlLQdJZ8cSY5GCefwIDWb3REjM7QJDLgSV+IERRHOm0R2c5dueJ5mB GK9DhFfJSgBLrxyUdYWDmw4IbnkLe/q2F3XMqCui8hZAhXDb/wpcabcW7noi/pK4oU KKtlDS7Cya/C2m7iZtMfbc1ZhX5N76f+NkNgDaobA/zuSkiIfMnDfsuo4coAnVonXg kE55immiFicSkg4JuWZywrUvU7tuX09yQvaY7w0vsVf9qP5YsIB6yvLp8BQMxbPbzp ZPinUYU2DRjXZEBe0Vfowu2RzsBLK0CzgvFLh/ssM9B4d9MZC+qetxgf/DIAOwFsaT 7mA13sHjG28eg== Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 07 Jul 2025 21:00:54 +0200 Message-Id: To: "Caterina Shablia" From: "Danilo Krummrich" Subject: Re: [PATCH v4 4/7] drm/gpuvm: Add a helper to check if two VA can be merged Cc: "Maarten Lankhorst" , "Maxime Ripard" , "Thomas Zimmermann" , "David Airlie" , "Simona Vetter" , "Frank Binns" , "Matt Coster" , "Karol Herbst" , "Lyude Paul" , "Boris Brezillon" , "Steven Price" , "Liviu Dudau" , "Lucas De Marchi" , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , "Rodrigo Vivi" , , , , , , "Asahi Lina" References: <20250707170442.1437009-1-caterina.shablia@collabora.com> <20250707170442.1437009-5-caterina.shablia@collabora.com> In-Reply-To: <20250707170442.1437009-5-caterina.shablia@collabora.com> On Mon Jul 7, 2025 at 7:04 PM CEST, Caterina Shablia wrote: > diff --git a/drivers/gpu/drm/drm_gpuvm.c b/drivers/gpu/drm/drm_gpuvm.c > index 05978c5c38b1..dc3c2f906400 100644 > --- a/drivers/gpu/drm/drm_gpuvm.c > +++ b/drivers/gpu/drm/drm_gpuvm.c > @@ -2098,12 +2098,48 @@ op_unmap_cb(const struct drm_gpuvm_ops *fn, void = *priv, > return fn->sm_step_unmap(&op, priv); > } > =20 > +static bool can_merge(struct drm_gpuvm *gpuvm, const struct drm_gpuva *a= , > + const struct drm_gpuva *b) > +{ > + /* Only GEM-based mappings can be merged, and they must point to > + * the same GEM object. > + */ > + if (a->gem.obj !=3D b->gem.obj || !a->gem.obj) > + return false; > + > + /* Let's keep things simple for now and force all flags to match. */ > + if (a->flags !=3D b->flags) > + return false; > + > + /* Order VAs for the rest of the checks. */ > + if (a->va.addr > b->va.addr) > + swap(a, b); > + > + /* We assume the caller already checked that VAs overlap or are > + * contiguous. > + */ > + if (drm_WARN_ON(gpuvm->drm, b->va.addr > a->va.addr + a->va.range)) > + return false; > + > + /* We intentionally ignore u64 underflows because all we care about > + * here is whether the VA diff matches the GEM offset diff. > + */ > + return b->va.addr - a->va.addr =3D=3D b->gem.offset - a->gem.offset; > +} > + > static int > __drm_gpuvm_sm_map(struct drm_gpuvm *gpuvm, > const struct drm_gpuvm_ops *ops, void *priv, > const struct drm_gpuvm_map_req *req) > { > struct drm_gpuva *va, *next; > + struct drm_gpuva reqva =3D { > + .va.addr =3D req->va.addr, > + .va.range =3D req->va.range, > + .gem.offset =3D req->gem.offset, > + .gem.obj =3D req->gem.obj, > + .flags =3D req->flags, Huh? Where does req->flags come from? I don't remember that this flag exist= s in struct drm_gpuvm_map_req in the preceding patch? > + }; > u64 req_end =3D req->va.addr + req->va.range; > int ret; > =20 > @@ -2116,12 +2152,9 @@ __drm_gpuvm_sm_map(struct drm_gpuvm *gpuvm, > u64 addr =3D va->va.addr; > u64 range =3D va->va.range; > u64 end =3D addr + range; > - bool merge =3D !!va->gem.obj; > + bool merge =3D can_merge(gpuvm, va, &reqva); I know you want to do the swap() trick above, but I don't like creating a temporary struct drm_gpuva with all the other uninitialized fields. If you really want this, can we please limit the scope? Maybe the following helper: static bool can_merge(struct drm_gpuvm *gpuvm, const struct drm_gpuva *va, struct drm_gpuvm_map_req *req) { struct drm_gpuva reqva =3D { ... }; return __can_merge(gpuvm, va, reqva); }