[module] added kvmfr kernel module for VM->VM shared memory

.gitignore

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+module/*.ko
+module/*.o
+module/*.mod.c
+module/.*
+module/Module.symvers
+module/modules.order

module/Makefile

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+obj-m += kvmfr.o
+
+all:
+	make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) modules
+
+clean:
+	make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) clean

module/README

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+This kernel module implements a basic interface to the IVSHMEM device for
+LookingGlass when using LookingGlass in VM->VM mode.
+
+== Compiling ==
+
+Make sure you have your kernel headers installed first, on Debian/Ubuntu use
+the following command.
+
+    apt-get install linux-headers-$(uname -r)
+
+Then simply run `make` and you're done.
+
+== Usage ==
+
+This module requires the `uio` module to be loaded first, loading it is as
+simple as:
+
+    modprobe uio
+    insmod kvmfr.ko
+
+This will create the `/dev/uio0` node that represents the KVMFR interface.
+To use the interface you need permission to access it by either creating a
+udev rule to ensure your user can read and write to it, or simply change it's
+ownership manually, ie:
+
+    sudo chown user:user /dev/uid0
+
+Usage with looking glass is simple, but you do need to speecify both the path
+and the size as LookingGlass can not determine the size by itself at this time.
+
+    ./looking-glass-client -f /dev/uio0 -L 16
+
+== Note ==
+
+This module is not strictly required, it is possible to access the device
+via the /sys interface directly, for example:
+
+    ./looking-glass-client -f /sys/devices/pci0000:00/0000:00:03.0/resource2_wc
+
+Obviously adjusting the PCI device IDs as required. However while this is
+possible it is not recommended as access to the shared memory may be slower.
+
+== Issues ==
+
+At this time VM->VM access atleast in this authors configurtion is slow, barely
+exceeding 15fps at 1200p, it is still yet to be determined if this is an
+architecture problem with this authors AMD ThreadRipper platform.

module/kvmfr.c

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+/*
+UIO KVMFR Driver
+Copyright (C) 2017 Geoffrey McRae <geoff@hostfission.com>
+https://looking-glass.hostfission.com
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; either version 2 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that 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.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#define PCI_LG_VENDOR_ID 0x1af4 //Red Hat Inc,
+#define PCI_LG_DEVICE_ID 0x1110 //Inter-VM shared memory
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+#include <linux/uio_driver.h>
+
+#include <asm/io.h>
+
+static int kvmfr_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
+{
+  struct uio_info *info;
+
+  info = kzalloc(sizeof(struct uio_info), GFP_KERNEL);
+  if (!info)
+    return -ENOMEM;
+
+  if (pci_enable_device(dev))
+    goto out_free;
+
+  if (pci_request_regions(dev, "kvmfr"))
+    goto out_disable;
+
+  info->mem[0].addr = pci_resource_start(dev, 2);
+  if (!info->mem[0].addr)
+    goto out_release;
+
+  info->mem[0].internal_addr = pci_iomap(dev, 2, 0);
+  if (!info->mem[0].internal_addr)
+    goto out_release;
+
+  info->mem[0].size    = pci_resource_len(dev, 2);
+  info->mem[0].memtype = UIO_MEM_PHYS;
+  info->name           = "KVMFR";
+  info->version        = "0.0.1";
+  info->irq            = 0;
+  info->irq_flags      = 0;
+  info->handler        = NULL;
+
+  if (uio_register_device(&dev->dev, info))
+    goto out_unmap;
+
+  pci_set_drvdata(dev, info);
+  return 0;
+
+out_unmap:
+  printk("unmap\n");
+  iounmap(info->mem[0].internal_addr);
+out_release:
+  printk("release\n");
+  pci_release_regions(dev);
+out_disable:
+  printk("disable\n");
+  pci_disable_device(dev);
+out_free:
+  printk("free\n");
+  kfree(info);
+  return -ENODEV;
+}
+
+static void kvmfr_pci_remove(struct pci_dev *dev)
+{
+  struct uio_info *info = pci_get_drvdata(dev);
+
+  uio_unregister_device(info);
+  pci_release_regions(dev);
+  pci_disable_device(dev);
+  iounmap(info->mem[0].internal_addr);
+
+  kfree(info);
+}
+
+static struct pci_device_id kvmfr_pci_ids[] =
+{
+  {
+    .vendor    = PCI_LG_VENDOR_ID,
+    .device    = PCI_LG_DEVICE_ID,
+    .subvendor = PCI_ANY_ID,
+    .subdevice = PCI_ANY_ID
+  },
+  { 0, }
+};
+
+static struct pci_driver kvmfr_pci_driver =
+{
+  .name     = "kvmfr",
+  .id_table = kvmfr_pci_ids,
+  .probe    = kvmfr_pci_probe,
+  .remove   = kvmfr_pci_remove
+};
+
+module_pci_driver(kvmfr_pci_driver);
+MODULE_DEVICE_TABLE(pci, kvmfr_pci_ids);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Geoffrey McRae");