From patchwork Tue Mar 18 19:22:41 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Almeida X-Patchwork-Id: 14021475 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 DC9DF1DF745; Tue, 18 Mar 2025 19:24:04 +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=1742325846; cv=pass; b=OJKRMCnIVfrCw+CZVMOpplGxdJh42SXjDeleH04b9pjeF+RsHVeCS/iDwXGPeZ+V9hJG/NYnqk4GY8xs4EvfnAsG3V3OOi3bKPnIVswiSpvseo/WfLVfzO4n2z9DsaF877GQbKsAfRmbTp0xUogISjz8b69UWbRAEdRg/O6sCy0= ARC-Message-Signature: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742325846; c=relaxed/simple; bh=vvTB8rkN7ljMSUXzRFh/rfPsl7C9GGs09UoRBBl3iyY=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=WuOWT8y9dfIIwa9QAjfVduuRNcu1Ot8NVcq7d8xn9pG1Dzz/CwT1TdJL5iuTLxUK3jyP5W0nvJzoGMQtAVcMr3huNWMNbWGThSiEAbCHQauxZ2NkS+7qMsFq2gmoT03HMA/FkevlAYo7kC1XT9YCJyI4+80TwTMh4x0zgNH91hE= 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=daniel.almeida@collabora.com header.b=TzxHbaWU; 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=daniel.almeida@collabora.com header.b="TzxHbaWU" ARC-Seal: i=1; a=rsa-sha256; t=1742325815; cv=none; d=zohomail.com; s=zohoarc; b=BKEbwh2MQCWz4P1R2zqqcPU93xs5X1S7FMSeWtTtupARQbFRbP1NpocXvCeq8f9AQMAPS8OvVMkHMTo/psATprDyBETB0ix77Mv4VK3bqL5k4siVwXnkfWukPa+tjL4OkBgkYQA3A4rbsoa7P1oKxTMjcT4Anjhm/TZZ7GdqUyQ= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1742325815; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=VFvk+dYAnpkou9AH4DFuJ+Nu9zjD0N7bOMF+5NpPK7A=; b=Me1Ts1r3qYGEt6jl99IAwxsZ3yyJvd2873HYaHmVuBWB8AJUpIRu2+chMl5eqyspcZjhmXuSIS7NedqUiWmJJZzftC6pkvTmXr57CKCIKqUPvY/KBKlMnlLjmqdljFy9GfsDuQ2Nz+N0jPwkFQ3QA4DqGx9cmCHuHsYXFENIMhc= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=daniel.almeida@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1742325815; s=zohomail; d=collabora.com; i=daniel.almeida@collabora.com; h=From:From:Date:Date:Subject:Subject:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-Id:Message-Id:References:In-Reply-To:To:To:Cc:Cc:Reply-To; bh=VFvk+dYAnpkou9AH4DFuJ+Nu9zjD0N7bOMF+5NpPK7A=; b=TzxHbaWU1iBonu2y8PYFsdKmU9LLZKO885R2SQtzuB2hitjZHptU1zrtk/2Eh0QR 6+iy+vZzwHlzhOPqalbScfJpCXuA9FV5yUp0l+7HdoDWzLAtgWKUriPso7wBR1L1viV 9jIMkxlP9SZjpCyUJdXpyQmiOrNdNAayUxGxTyj0= Received: by mx.zohomail.com with SMTPS id 1742325814316498.85405764067946; Tue, 18 Mar 2025 12:23:34 -0700 (PDT) From: Daniel Almeida Date: Tue, 18 Mar 2025 16:22:41 -0300 Subject: [PATCH 7/7] rust: drm: gem: shmem: Add share_dma_resv() function Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250318-drm-gem-shmem-v1-7-64b96511a84f@collabora.com> References: <20250318-drm-gem-shmem-v1-0-64b96511a84f@collabora.com> In-Reply-To: <20250318-drm-gem-shmem-v1-0-64b96511a84f@collabora.com> To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, Danilo Krummrich , Asahi Lina , Daniel Almeida X-Mailer: b4 0.14.2 X-ZohoMailClient: External From: Asahi Lina Allow a GEM object to share another object's DMA reservation, for use with drm_gpuvm. To keep memory safety, we hold a reference to the GEM object owning the resv, and drop it when the child object is freed. Signed-off-by: Asahi Lina Signed-off-by: Daniel Almeida --- rust/kernel/drm/gem/shmem.rs | 33 ++++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) diff --git a/rust/kernel/drm/gem/shmem.rs b/rust/kernel/drm/gem/shmem.rs index fdf7dd7f2408bd2857f5b72027ef48e29c9dd9e3..e026b26a4895daea0534b93296da9a33683aa432 100644 --- a/rust/kernel/drm/gem/shmem.rs +++ b/rust/kernel/drm/gem/shmem.rs @@ -17,7 +17,7 @@ slice, }; -use gem::BaseObject; +use gem::{BaseObject, IntoGEMObject}; /// Trait which must be implemented by drivers using shmem-backed GEM objects. pub trait DriverObject: gem::BaseDriverObject> { @@ -72,6 +72,8 @@ pub struct Object { // The DRM core ensures the Device exists as long as its objects exist, so we don't need to // manage the reference count here. dev: *const bindings::drm_device, + // Parent object that owns this object's DMA reservation object + parent_resv_obj: *const bindings::drm_gem_object, #[pin] inner: T, } @@ -101,6 +103,7 @@ unsafe impl init::Zeroable for bindings::drm_gem_shmem_object {} // SAFETY: GEM ensures the device lives as long as its objects live inner <- T::new(unsafe { device::Device::borrow(dev)}, size), dev, + parent_resv_obj: core::ptr::null(), }); // SAFETY: p is a valid pointer to an uninitialized Object. @@ -135,6 +138,15 @@ unsafe impl init::Zeroable for bindings::drm_gem_shmem_object {} core::ptr::drop_in_place(&mut (*p).inner); } + // SAFETY: parent_resv_obj is either NULL or a valid reference to the + // GEM object owning the DMA reservation for this object, which we drop + // here. + unsafe { + if !(*p).parent_resv_obj.is_null() { + bindings::drm_gem_object_put((*p).parent_resv_obj as *const _ as *mut _); + } + } + // SAFETY: This pointer has to be valid, since p is valid unsafe { bindings::drm_gem_shmem_free(&mut (*p).obj); @@ -236,6 +248,25 @@ pub fn vmap(&self) -> Result> { pub fn set_wc(&mut self, map_wc: bool) { self.obj.set_map_wc(map_wc); } + + /// Share the dma_resv object from another GEM object. + /// + /// Should be called before the object is used/shared. Can only be called once. + pub fn share_dma_resv(&mut self, from_object: &impl IntoGEMObject) -> Result { + let from_obj = from_object.gem_obj(); + if !self.parent_resv_obj.is_null() { + Err(EBUSY) + } else { + // SAFETY: from_obj is a valid object pointer per the trait Invariant. + unsafe { + bindings::drm_gem_object_get(from_obj as *const _ as *mut _); + } + self.parent_resv_obj = from_obj; + let gem = self.mut_gem_obj(); + gem.resv = from_obj.resv; + Ok(()) + } + } } impl Deref for Object {