From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- samples/vfio-mdev/mdpy-fb.c | 233 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 233 insertions(+) create mode 100644 samples/vfio-mdev/mdpy-fb.c (limited to 'samples/vfio-mdev/mdpy-fb.c') diff --git a/samples/vfio-mdev/mdpy-fb.c b/samples/vfio-mdev/mdpy-fb.c new file mode 100644 index 000000000..149af7f59 --- /dev/null +++ b/samples/vfio-mdev/mdpy-fb.c @@ -0,0 +1,233 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Framebuffer driver for mdpy (mediated virtual pci display device). + * + * See mdpy-defs.h for device specs + * + * (c) Gerd Hoffmann + * + * Using some code snippets from simplefb and cirrusfb. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + */ +#include +#include +#include +#include +#include +#include +#include "mdpy-defs.h" + +static const struct fb_fix_screeninfo mdpy_fb_fix = { + .id = "mdpy-fb", + .type = FB_TYPE_PACKED_PIXELS, + .visual = FB_VISUAL_TRUECOLOR, + .accel = FB_ACCEL_NONE, +}; + +static const struct fb_var_screeninfo mdpy_fb_var = { + .height = -1, + .width = -1, + .activate = FB_ACTIVATE_NOW, + .vmode = FB_VMODE_NONINTERLACED, + + .bits_per_pixel = 32, + .transp.offset = 24, + .red.offset = 16, + .green.offset = 8, + .blue.offset = 0, + .transp.length = 8, + .red.length = 8, + .green.length = 8, + .blue.length = 8, +}; + +#define PSEUDO_PALETTE_SIZE 16 + +struct mdpy_fb_par { + u32 palette[PSEUDO_PALETTE_SIZE]; +}; + +static int mdpy_fb_setcolreg(u_int regno, u_int red, u_int green, u_int blue, + u_int transp, struct fb_info *info) +{ + u32 *pal = info->pseudo_palette; + u32 cr = red >> (16 - info->var.red.length); + u32 cg = green >> (16 - info->var.green.length); + u32 cb = blue >> (16 - info->var.blue.length); + u32 value, mask; + + if (regno >= PSEUDO_PALETTE_SIZE) + return -EINVAL; + + value = (cr << info->var.red.offset) | + (cg << info->var.green.offset) | + (cb << info->var.blue.offset); + if (info->var.transp.length > 0) { + mask = (1 << info->var.transp.length) - 1; + mask <<= info->var.transp.offset; + value |= mask; + } + pal[regno] = value; + + return 0; +} + +static void mdpy_fb_destroy(struct fb_info *info) +{ + if (info->screen_base) + iounmap(info->screen_base); +} + +static const struct fb_ops mdpy_fb_ops = { + .owner = THIS_MODULE, + FB_DEFAULT_IOMEM_OPS, + .fb_destroy = mdpy_fb_destroy, + .fb_setcolreg = mdpy_fb_setcolreg, +}; + +static int mdpy_fb_probe(struct pci_dev *pdev, + const struct pci_device_id *ent) +{ + struct fb_info *info; + struct mdpy_fb_par *par; + u32 format, width, height; + int ret; + + ret = pci_enable_device(pdev); + if (ret < 0) + return ret; + + ret = pci_request_regions(pdev, "mdpy-fb"); + if (ret < 0) + goto err_disable_dev; + + pci_read_config_dword(pdev, MDPY_FORMAT_OFFSET, &format); + pci_read_config_dword(pdev, MDPY_WIDTH_OFFSET, &width); + pci_read_config_dword(pdev, MDPY_HEIGHT_OFFSET, &height); + if (format != DRM_FORMAT_XRGB8888) { + pci_err(pdev, "format mismatch (0x%x != 0x%x)\n", + format, DRM_FORMAT_XRGB8888); + ret = -EINVAL; + goto err_release_regions; + } + if (width < 100 || width > 10000) { + pci_err(pdev, "width (%d) out of range\n", width); + ret = -EINVAL; + goto err_release_regions; + } + if (height < 100 || height > 10000) { + pci_err(pdev, "height (%d) out of range\n", height); + ret = -EINVAL; + goto err_release_regions; + } + pci_info(pdev, "mdpy found: %dx%d framebuffer\n", + width, height); + + info = framebuffer_alloc(sizeof(struct mdpy_fb_par), &pdev->dev); + if (!info) { + ret = -ENOMEM; + goto err_release_regions; + } + pci_set_drvdata(pdev, info); + par = info->par; + + info->fix = mdpy_fb_fix; + info->fix.smem_start = pci_resource_start(pdev, 0); + info->fix.smem_len = pci_resource_len(pdev, 0); + info->fix.line_length = width * 4; + + info->var = mdpy_fb_var; + info->var.xres = width; + info->var.yres = height; + info->var.xres_virtual = width; + info->var.yres_virtual = height; + + info->screen_size = info->fix.smem_len; + info->screen_base = ioremap(info->fix.smem_start, + info->screen_size); + if (!info->screen_base) { + pci_err(pdev, "ioremap(pcibar) failed\n"); + ret = -EIO; + goto err_release_fb; + } + + info->fbops = &mdpy_fb_ops; + info->pseudo_palette = par->palette; + + ret = register_framebuffer(info); + if (ret < 0) { + pci_err(pdev, "mdpy-fb device register failed: %d\n", ret); + goto err_unmap; + } + + pci_info(pdev, "fb%d registered\n", info->node); + return 0; + +err_unmap: + iounmap(info->screen_base); + +err_release_fb: + framebuffer_release(info); + +err_release_regions: + pci_release_regions(pdev); + +err_disable_dev: + pci_disable_device(pdev); + + return ret; +} + +static void mdpy_fb_remove(struct pci_dev *pdev) +{ + struct fb_info *info = pci_get_drvdata(pdev); + + unregister_framebuffer(info); + iounmap(info->screen_base); + framebuffer_release(info); + pci_release_regions(pdev); + pci_disable_device(pdev); +} + +static struct pci_device_id mdpy_fb_pci_table[] = { + { + .vendor = MDPY_PCI_VENDOR_ID, + .device = MDPY_PCI_DEVICE_ID, + .subvendor = MDPY_PCI_SUBVENDOR_ID, + .subdevice = MDPY_PCI_SUBDEVICE_ID, + }, { + /* end of list */ + } +}; + +static struct pci_driver mdpy_fb_pci_driver = { + .name = "mdpy-fb", + .id_table = mdpy_fb_pci_table, + .probe = mdpy_fb_probe, + .remove = mdpy_fb_remove, +}; + +static int __init mdpy_fb_init(void) +{ + int ret; + + ret = pci_register_driver(&mdpy_fb_pci_driver); + if (ret) + return ret; + + return 0; +} + +module_init(mdpy_fb_init); + +MODULE_DEVICE_TABLE(pci, mdpy_fb_pci_table); +MODULE_DESCRIPTION("Framebuffer driver for mdpy (mediated virtual pci display device)"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1