From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender4-pp-f112.zoho.com (sender4-pp-f112.zoho.com [136.143.188.112]) (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 21C1C27CCEE for ; Sat, 28 Feb 2026 01:01:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.112 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772240484; cv=pass; b=p8LYDY9RyPwP40Z/NZOSyxxC4E3ekqoDGNx1lcrExw+3rrJV9dfWcfKC5VHnz1k+vxJzrpGBwu67d/S37AYjCFGsLXunzqtD08tJ10nUj4h1EwIO8H2JD5xTtnA6Esxjy4fSY8HVfOV/iTOo/+E4GQpBVNtk3JLlA6fLa1oYMWs= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772240484; c=relaxed/simple; bh=Lm2qr0C1J6E6HzE08o6OLmtA/Jo0aoUV/5FgiNAK6jI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FwJ0e+uNftsQ11Nr1Tn3/FyuREYAtbpiRYL/+bcdTCm15FqKlLv7IHkE8/8ATLZLdAq6kdDAcvo+ktkrHl6Zu/OYd1cNcMd6tm4x0nxa8m8lAkj/OJAVS/269MRuXRotfQuevVJSWsJYyLcVgEcarETEwe2ADBArcReNcgdr1iw= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (1024-bit key) header.d=collabora.com header.i=deborah.brouwer@collabora.com header.b=gjDb4m9u; arc=pass smtp.client-ip=136.143.188.112 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=collabora.com header.i=deborah.brouwer@collabora.com header.b="gjDb4m9u" ARC-Seal: i=1; a=rsa-sha256; t=1772240474; cv=none; d=zohomail.com; s=zohoarc; b=lfIKqghSlKRsr1v3j4O6YwUstab/7Yy3ro1FFjCtluHHRFBxw4CF0/7JREycbTP6mmbOu5Dg2csy0+uygnIWig9+agtPEWONxul0EOa1hirPIxgbJODm0XZE5/1pjC9cA7NihMoyIwIc92ie9Npnt92//WnpAuRmZ+W/vk67bM0= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1772240474; h=Content-Type:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=i5sxaA2PVY8xbh1tFOsrEa6kopnjclUJ02+xow5C6wI=; b=mKhFerBv+U7SoPU9N6ju/EoDemLW5ATM9i18jD/8Fj9QTQaWVyafCj2l+TpiLMN5wtQUT0sndVWXhG11w5/lEUki5MSrk2MqszaCfSjktX5mjaRbmyJQKIQxoFYIJxXhAHsCWbnVwjTrshGJz876PN+t6B6qfGN5Wz7Z5GGpKWw= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=deborah.brouwer@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1772240473; s=zohomail; d=collabora.com; i=deborah.brouwer@collabora.com; h=Date:Date:From:From:To:To:Cc:Cc:Subject:Subject:Message-ID:References:MIME-Version:Content-Type:In-Reply-To:Message-Id:Reply-To; bh=i5sxaA2PVY8xbh1tFOsrEa6kopnjclUJ02+xow5C6wI=; b=gjDb4m9uh9NzREgbjFyLYB6soyPnLxNhVUw7d/Ys6nZurMwpHg66Dp29n9E5VPO5 R7jNNBAnHsmVwzCv67ZODqdPV1kDSyNxWo6BK65H+QCaGdq5NGpEKIl0hILRH4Dor8t ZM36dpWA+MOHQuSwZ6zzxCTdjLfcSl5Uh/TnI9vA= Received: by mx.zohomail.com with SMTPS id 1772240471537395.6159296527935; Fri, 27 Feb 2026 17:01:11 -0800 (PST) Date: Fri, 27 Feb 2026 17:01:11 -0800 From: Deborah Brouwer To: Boris Brezillon Cc: dri-devel@lists.freedesktop.org, rust-for-linux@vger.kernel.org, daniel.almeida@collabora.com, aliceryhl@google.com, beata.michalska@arm.com, lyude@redhat.com Subject: Re: [PATCH 10/12] drm/tyr: add a kernel buffer object Message-ID: References: <20260212013713.304343-1-deborah.brouwer@collabora.com> <20260212013713.304343-11-deborah.brouwer@collabora.com> <20260212120043.36a560e9@fedora> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260212120043.36a560e9@fedora> On Thu, Feb 12, 2026 at 12:00:43PM +0100, Boris Brezillon wrote: > On Wed, 11 Feb 2026 17:37:11 -0800 > Deborah Brouwer wrote: > > > Introduce a buffer object type (KernelBo) for internal driver allocations > > that are managed by the kernel rather than userspace. > > > > KernelBo wraps a GEM shmem object and automatically handles GPU virtual > > address space mapping during creation and unmapping on drop. This provides > > a safe and convenient way for the driver to both allocate and clean up > > internal buffers for kernel-managed resources. > > > > Co-developed-by: Boris Brezillon > > Signed-off-by: Boris Brezillon > > Signed-off-by: Deborah Brouwer > > --- > > drivers/gpu/drm/tyr/gem.rs | 74 +++++++++++++++++++++++++++++++++++--- > > 1 file changed, 70 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/gpu/drm/tyr/gem.rs b/drivers/gpu/drm/tyr/gem.rs > > index 111acf33993f..3807810be7ea 100644 > > --- a/drivers/gpu/drm/tyr/gem.rs > > +++ b/drivers/gpu/drm/tyr/gem.rs > > @@ -4,6 +4,8 @@ > > //! This module provides buffer object (BO) management functionality using > > //! DRM's GEM subsystem with shmem backing. > > > > +use core::ops::Range; > > + > > use kernel::{ > > drm::{ > > gem, > > @@ -11,12 +13,22 @@ > > DeviceContext, // > > }, > > prelude::*, > > - sync::aref::ARef, // > > + sync::{ > > + aref::ARef, > > + Arc, > > + ArcBorrow, // > > + }, > > }; > > > > -use crate::driver::{ > > - TyrDrmDevice, > > - TyrDrmDriver, // > > +use crate::{ > > + driver::{ > > + TyrDrmDevice, > > + TyrDrmDriver, // > > + }, > > + vm::{ > > + Vm, > > + VmMapFlags, // > > + }, > > }; > > > > /// Tyr's DriverObject type for GEM objects. > > @@ -61,3 +73,57 @@ pub(crate) fn new_dummy_object(ddev: &TyrDrmDevice) -> > > > > Ok(bo) > > } > > + > > +/// A buffer object that is owned and managed by Tyr rather than userspace. > > +pub(crate) struct KernelBo { > > + #[expect(dead_code)] > > + pub(crate) bo: ARef, > > + vm: Arc, > > + va_range: Range, > > Missing docs for all those fields. Ack. > > > +} > > + > > +impl KernelBo { > > + /// Creates a new kernel-owned buffer object and maps it into GPU VA space. > > + #[expect(dead_code)] > > + pub(crate) fn new( > > + ddev: &TyrDrmDevice, > > + vm: ArcBorrow<'_, Vm>, > > + size: u64, > > + va: u64, > > I'm already thinking about the next step (automatic VA-range > allocation), and I'd be tempted to go directly for: > > enum KernelBoVaAlloc { > Explicit(u64), > } > > so we can easily extend it with > > enum KernelBoVaAlloc { > Auto, > Explicit(u64), > } > > when we have to. > Sure that is easily done. > > + flags: VmMapFlags, > > + ) -> Result { > > + let bo = gem::shmem::Object::::new( > > + ddev, > > + size as usize, > > + shmem::ObjectConfig { > > + map_wc: true, > > + parent_resv_obj: None, > > + }, > > + BoCreateArgs { flags: 0 }, > > + )?; > > + > > + vm.map_bo_range(&bo, 0, size, va, flags)?; > > + > > + Ok(KernelBo { > > + bo, > > + vm: vm.into(), > > + va_range: va..(va + size), > > + }) > > + } > > +} > > + > > +impl Drop for KernelBo { > > + fn drop(&mut self) { > > + let va = self.va_range.start; > > + let size = self.va_range.end - self.va_range.start; > > + > > + if let Err(e) = self.vm.unmap_range(va, size) { > > + pr_err!( > > + "Failed to unmap KernelBo range {:#x}..{:#x}: {:?}\n", > > + self.va_range.start, > > + self.va_range.end, > > + e > > + ); > > + } > > + } > > +} >