From nobody Wed May 13 16:45:28 2026 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 2A4A923EA8B for ; Fri, 1 May 2026 00:01:32 +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=1777593694; cv=pass; b=ms63m8XCn+cooDOKVlOV92/UFO+aQ6H0dnzyICHyrk33Sl6TjW+PjyrLp3w/zOspYvN+0SujP5e8L4hdRufutQB/VPAjIIfOF8Z+INwm+EkjD6FfH4aXccmQ8N7hsjolFXtvjXBdOs/EMoIj3lS4k9z95RtK6i1/Yt0e6gLVATo= ARC-Message-Signature: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777593694; c=relaxed/simple; bh=jNx7WM37+RpgdwoBKj7KcAoRNPtqBcCRC8grN0CRelo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=fF2z7zySKvV/taG3GYmkPrEsRsuKS2Mpijzuc1rR9sFbM1M7odxZD9Mgax1HWCTyx9gCjJyKY9KUlmGtfNlgE3lFB+oK4ptd8sDxYYGfy6HjHEY1YWm+pbKfbZaMi+SA4OPSqeDa03eLJEmi+zphJux+LrzHUF8HrO+usCfycOM= 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=dmitry.osipenko@collabora.com header.b=YpwLmnGx; 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=dmitry.osipenko@collabora.com header.b="YpwLmnGx" ARC-Seal: i=1; a=rsa-sha256; t=1777593664; cv=none; d=zohomail.com; s=zohoarc; b=mBg5rR7hOOaNu2ujoTFwS4iQ5DmZ76VkP2ZEIejuPughBqvIlYExdxqichjYfrINa6EVpYbhJPbuxw9OnD2BDCUqbzd7gIW6ictjLYAQ+wlZaBuMb2q6FXSXStHWf5bW3Ggnwgg+HtP459asFgJV//hOpBUOqv7xb/RdlW3VnSw= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1777593664; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:MIME-Version:Message-ID:Subject:Subject:To:To:Message-Id:Reply-To; bh=38D+j2FFCJtfyIIFhcx+mSM0sBnylQNjunu3hbPRVWU=; b=CNIwwxPma2tJO7wUXct1TOB62vwUuJ7F6hNbc8HJQcuZdJ7tA5cichndsa2ZkQWooLO/Dyss7gJ8y6B4GnZLm6PT6AOqxI/ISiQd4bOZDKuY61iWtj3CUGwsygSV+WOJdVQHhgMNou54YAtLVylNczklk9xm4O9vaI02SxBkMcI= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=dmitry.osipenko@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1777593664; s=zohomail; d=collabora.com; i=dmitry.osipenko@collabora.com; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To; bh=38D+j2FFCJtfyIIFhcx+mSM0sBnylQNjunu3hbPRVWU=; b=YpwLmnGx1FV5e5p2GDhRCYG75ahRY/jIy5uAlweQBaEMDnHXuGgPVcdq0V0zJYsz orEfN5j5CJI/HpEFXUnwymvomecsatlvem2lFWlsV7Hw8SQoIlfxxZL8Jz7DfCCwmVY uDC9TDv/okb2qF2gGkQm+LKBoeR5MdBpt2HJEzrs= Received: by mx.zohomail.com with SMTPS id 1777593661744215.50532790947523; Thu, 30 Apr 2026 17:01:01 -0700 (PDT) From: Dmitry Osipenko To: David Airlie , Gerd Hoffmann , Gurchetan Singh , Chia-I Wu , Pierre-Eric Pelloux-Prayer , Alyssa Rosenzweig Cc: Rob Clark , dri-devel@lists.freedesktop.org, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, kernel@collabora.com, Nagapuri Ramesh Subject: [PATCH v2] drm/virtio: Extend blob UAPI with deferred-mapping hinting Date: Fri, 1 May 2026 03:00:43 +0300 Message-ID: <20260501000043.2483678-1-dmitry.osipenko@collabora.com> X-Mailer: git-send-email 2.53.0 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 X-ZohoMailClient: External Content-Type: text/plain; charset="utf-8" If userspace never maps GEM object, then BO wastes hostmem space because VirtIO-GPU driver maps VRAM BO at the BO's creating time. Make mappings on-demand by adding new RESOURCE_CREATE_BLOB IOCTL/UAPI hinting flag telling that host mapping should be deferred until first mapping is made when the flag is set by userspace. Signed-off-by: Dmitry Osipenko Reviewed-by: Rob Clark --- Changelog: v2: Rebased on recent kernel. Intel i915 native ctx landed to Mesa, lets to proceed with merging the mapping hint as a first user of the feature. drivers/gpu/drm/virtio/virtgpu_drv.h | 2 ++ drivers/gpu/drm/virtio/virtgpu_ioctl.c | 1 + drivers/gpu/drm/virtio/virtgpu_vram.c | 30 +++++++++++++++++++++----- include/uapi/drm/virtgpu_drm.h | 4 ++++ 4 files changed, 32 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/= virtgpu_drv.h index f17660a71a3e..6f49213e23f8 100644 --- a/drivers/gpu/drm/virtio/virtgpu_drv.h +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h @@ -84,6 +84,7 @@ struct virtio_gpu_object_params { uint32_t blob_mem; uint32_t blob_flags; uint64_t blob_id; + uint32_t blob_hints; }; =20 struct virtio_gpu_object { @@ -507,6 +508,7 @@ struct sg_table *virtio_gpu_vram_map_dma_buf(struct vir= tio_gpu_object *bo, void virtio_gpu_vram_unmap_dma_buf(struct device *dev, struct sg_table *sgt, enum dma_data_direction dir); +void virtio_gpu_vram_map_deferred(struct virtio_gpu_object_vram *vram); =20 /* virtgpu_submit.c */ int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data, diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virti= o/virtgpu_ioctl.c index c33c057365f8..01daa72b1310 100644 --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c @@ -489,6 +489,7 @@ static int verify_blob(struct virtio_gpu_device *vgdev, params->size =3D rc_blob->size; params->blob =3D true; params->blob_flags =3D rc_blob->blob_flags; + params->blob_hints =3D rc_blob->blob_hints; return 0; } =20 diff --git a/drivers/gpu/drm/virtio/virtgpu_vram.c b/drivers/gpu/drm/virtio= /virtgpu_vram.c index 084e80227433..4ae3cbc35dd3 100644 --- a/drivers/gpu/drm/virtio/virtgpu_vram.c +++ b/drivers/gpu/drm/virtio/virtgpu_vram.c @@ -3,6 +3,8 @@ =20 #include =20 +static DEFINE_MUTEX(map_lock); + static void virtio_gpu_vram_free(struct drm_gem_object *obj) { struct virtio_gpu_object *bo =3D gem_to_virtio_gpu_obj(obj); @@ -42,6 +44,11 @@ static int virtio_gpu_vram_mmap(struct drm_gem_object *o= bj, if (!(bo->blob_flags & VIRTGPU_BLOB_FLAG_USE_MAPPABLE)) return -EINVAL; =20 + virtio_gpu_vram_map_deferred(vram); + + if (vram->map_state =3D=3D STATE_INITIALIZING) + virtio_gpu_notify(vgdev); + wait_event(vgdev->resp_wq, vram->map_state !=3D STATE_INITIALIZING); if (vram->map_state !=3D STATE_OK) return -EINVAL; @@ -218,14 +225,27 @@ int virtio_gpu_vram_create(struct virtio_gpu_device *= vgdev, =20 virtio_gpu_cmd_resource_create_blob(vgdev, &vram->base, params, NULL, 0); - if (params->blob_flags & VIRTGPU_BLOB_FLAG_USE_MAPPABLE) { - ret =3D virtio_gpu_vram_map(&vram->base); - if (ret) { - virtio_gpu_vram_free(obj); - return ret; + if (!(params->blob_hints & DRM_VIRTGPU_BLOB_FLAG_HINT_DEFER_MAPPING)) { + if (params->blob_flags & VIRTGPU_BLOB_FLAG_USE_MAPPABLE) { + ret =3D virtio_gpu_vram_map(&vram->base); + if (ret) { + virtio_gpu_vram_free(obj); + return ret; + } } } =20 *bo_ptr =3D &vram->base; return 0; } + +void virtio_gpu_vram_map_deferred(struct virtio_gpu_object_vram *vram) +{ + if (!(vram->base.blob_flags & VIRTGPU_BLOB_FLAG_USE_MAPPABLE)) + return; + + mutex_lock(&map_lock); + if (!drm_mm_node_allocated(&vram->vram_node)) + virtio_gpu_vram_map(&vram->base); + mutex_unlock(&map_lock); +} diff --git a/include/uapi/drm/virtgpu_drm.h b/include/uapi/drm/virtgpu_drm.h index 9debb320c34b..ba09a4ee3e77 100644 --- a/include/uapi/drm/virtgpu_drm.h +++ b/include/uapi/drm/virtgpu_drm.h @@ -200,6 +200,10 @@ struct drm_virtgpu_resource_create_blob { __u32 cmd_size; __u64 cmd; __u64 blob_id; + +#define DRM_VIRTGPU_BLOB_FLAG_HINT_DEFER_MAPPING 0x0001 + __u32 blob_hints; + __u32 pad2; }; =20 #define VIRTGPU_CONTEXT_PARAM_CAPSET_ID 0x0001 --=20 2.53.0