sample: vfio bochs vbe display (host device for bochs-drm)

Display device, demo-ing the vfio dmabuf display interface
(VFIO_GFX_PLANE_TYPE_DMABUF).  Compatible enough to qemu stdvga
that bochs-drm.ko can be used as guest driver.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

3 files changed, 1420 insertions, 0 deletions

diff --git a/samples/Kconfig b/samples/Kconfig
index a6ff147d8744..3aeaaca77831 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -132,6 +132,19 @@ config SAMPLE_VFIO_MDEV_MDPY_FB
         help
           Guest fbdev driver for the virtual display sample driver.
 
+config SAMPLE_VFIO_MDEV_MBOCHS
+        tristate "Build VFIO mdpy example mediated device sample code -- loadable modules only"
+        depends on VFIO_MDEV_DEVICE && m
+        help
+          Build a virtual display sample driver for use as a VFIO
+          mediated device.  It supports the region display interface
+          (VFIO_GFX_PLANE_TYPE_DMABUF).
+          Emulate enough of qemu stdvga to make bochs-drm.ko happy.
+          That is basically the vram memory bar and the bochs dispi
+          interface vbe registers in the mmio register bar.
+          Specifically it does *not* include any legacy vga stuff.
+          Device looks a lot like "qemu -device secondary-vga".
+
 config SAMPLE_STATX
         bool "Build example extended-stat using code"
         depends on BROKEN
diff --git a/samples/vfio-mdev/Makefile b/samples/vfio-mdev/Makefile
index 7a5790aaec9c..7db889ca135c 100644
--- a/samples/vfio-mdev/Makefile
+++ b/samples/vfio-mdev/Makefile
@@ -1,3 +1,4 @@
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MTTY) += mtty.o
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MDPY) += mdpy.o
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MDPY_FB) += mdpy-fb.o
+obj-$(CONFIG_SAMPLE_VFIO_MDEV_MBOCHS) += mbochs.o
diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
new file mode 100644
index 000000000000..2960e26c6ea4
--- /dev/null
+++ b/samples/vfio-mdev/mbochs.c
@@ -0,0 +1,1406 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Mediated virtual PCI display host device driver
+ *
+ * Emulate enough of qemu stdvga to make bochs-drm.ko happy.  That is
+ * basically the vram memory bar and the bochs dispi interface vbe
+ * registers in the mmio register bar.  Specifically it does *not*
+ * include any legacy vga stuff.  Device looks a lot like "qemu -device
+ * secondary-vga".
+ *
+ *   (c) Gerd Hoffmann <kraxel@redhat.com>
+ *
+ * based on mtty driver which is:
+ *   Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
+ *       Author: Neo Jia <cjia@nvidia.com>
+ *               Kirti Wankhede <kwankhede@nvidia.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/cdev.h>
+#include <linux/vfio.h>
+#include <linux/iommu.h>
+#include <linux/sysfs.h>
+#include <linux/mdev.h>
+#include <linux/pci.h>
+#include <linux/dma-buf.h>
+#include <linux/highmem.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_rect.h>
+#include <drm/drm_modeset_lock.h>
+#include <drm/drm_property.h>
+#include <drm/drm_plane.h>
+
+
+#define VBE_DISPI_INDEX_ID              0x0
+#define VBE_DISPI_INDEX_XRES            0x1
+#define VBE_DISPI_INDEX_YRES            0x2
+#define VBE_DISPI_INDEX_BPP             0x3
+#define VBE_DISPI_INDEX_ENABLE          0x4
+#define VBE_DISPI_INDEX_BANK            0x5
+#define VBE_DISPI_INDEX_VIRT_WIDTH      0x6
+#define VBE_DISPI_INDEX_VIRT_HEIGHT     0x7
+#define VBE_DISPI_INDEX_X_OFFSET        0x8
+#define VBE_DISPI_INDEX_Y_OFFSET        0x9
+#define VBE_DISPI_INDEX_VIDEO_MEMORY_64K 0xa
+#define VBE_DISPI_INDEX_COUNT           0xb
+
+#define VBE_DISPI_ID0                   0xB0C0
+#define VBE_DISPI_ID1                   0xB0C1
+#define VBE_DISPI_ID2                   0xB0C2
+#define VBE_DISPI_ID3                   0xB0C3
+#define VBE_DISPI_ID4                   0xB0C4
+#define VBE_DISPI_ID5                   0xB0C5
+
+#define VBE_DISPI_DISABLED              0x00
+#define VBE_DISPI_ENABLED               0x01
+#define VBE_DISPI_GETCAPS               0x02
+#define VBE_DISPI_8BIT_DAC              0x20
+#define VBE_DISPI_LFB_ENABLED           0x40
+#define VBE_DISPI_NOCLEARMEM            0x80
+
+
+#define MBOCHS_NAME               "mbochs"
+#define MBOCHS_CLASS_NAME         "mbochs"
+
+#define MBOCHS_CONFIG_SPACE_SIZE  0xff
+#define MBOCHS_MMIO_BAR_OFFSET    PAGE_SIZE
+#define MBOCHS_MMIO_BAR_SIZE      PAGE_SIZE
+#define MBOCHS_MEMORY_BAR_OFFSET  (MBOCHS_MMIO_BAR_OFFSET + \
+                                   MBOCHS_MMIO_BAR_SIZE)
+
+#define STORE_LE16(addr, val)   (*(u16 *)addr = val)
+#define STORE_LE32(addr, val)   (*(u32 *)addr = val)
+
+
+MODULE_LICENSE("GPL v2");
+
+static int max_mbytes = 256;
+module_param_named(count, max_mbytes, int, 0444);
+MODULE_PARM_DESC(mem, "megabytes available to " MBOCHS_NAME " devices");
+
+
+#define MBOCHS_TYPE_1 "small"
+#define MBOCHS_TYPE_2 "medium"
+#define MBOCHS_TYPE_3 "large"
+
+static const struct mbochs_type {
+        const char *name;
+        u32 mbytes;
+} mbochs_types[] = {
+        {
+                .name   = MBOCHS_CLASS_NAME "-" MBOCHS_TYPE_1,
+                .mbytes = 4,
+        }, {
+                .name   = MBOCHS_CLASS_NAME "-" MBOCHS_TYPE_2,
+                .mbytes = 16,
+        }, {
+                .name   = MBOCHS_CLASS_NAME "-" MBOCHS_TYPE_3,
+                .mbytes = 64,
+        },
+};
+
+
+static dev_t            mbochs_devt;
+static struct class     *mbochs_class;
+static struct cdev      mbochs_cdev;
+static struct device    mbochs_dev;
+static int              mbochs_used_mbytes;
+
+struct mbochs_mode {
+        u32 drm_format;
+        u32 bytepp;
+        u32 width;
+        u32 height;
+        u32 stride;
+        u32 __pad;
+        u64 offset;
+        u64 size;
+};
+
+struct mbochs_dmabuf {
+        struct mbochs_mode mode;
+        u32 id;
+        struct page **pages;
+        pgoff_t pagecount;
+        struct dma_buf *buf;
+        struct mdev_state *mdev_state;
+        struct list_head next;
+        bool unlinked;
+};
+
+/* State of each mdev device */
+struct mdev_state {
+        u8 *vconfig;
+        u64 bar_mask[3];
+        u32 memory_bar_mask;
+        struct mutex ops_lock;
+        struct mdev_device *mdev;
+        struct vfio_device_info dev_info;
+
+        const struct mbochs_type *type;
+        u16 vbe[VBE_DISPI_INDEX_COUNT];
+        u64 memsize;
+        struct page **pages;
+        pgoff_t pagecount;
+
+        struct list_head dmabufs;
+        u32 active_id;
+        u32 next_id;
+};
+
+static const char *vbe_name_list[VBE_DISPI_INDEX_COUNT] = {
+        [VBE_DISPI_INDEX_ID]               = "id",
+        [VBE_DISPI_INDEX_XRES]             = "xres",
+        [VBE_DISPI_INDEX_YRES]             = "yres",
+        [VBE_DISPI_INDEX_BPP]              = "bpp",
+        [VBE_DISPI_INDEX_ENABLE]           = "enable",
+        [VBE_DISPI_INDEX_BANK]             = "bank",
+        [VBE_DISPI_INDEX_VIRT_WIDTH]       = "virt-width",
+        [VBE_DISPI_INDEX_VIRT_HEIGHT]      = "virt-height",
+        [VBE_DISPI_INDEX_X_OFFSET]         = "x-offset",
+        [VBE_DISPI_INDEX_Y_OFFSET]         = "y-offset",
+        [VBE_DISPI_INDEX_VIDEO_MEMORY_64K] = "video-mem",
+};
+
+static const char *vbe_name(u32 index)
+{
+        if (index < ARRAY_SIZE(vbe_name_list))