lguest: the host code

This is the code for the "lg.ko" module, which allows lguest guests to
be launched.

[akpm@linux-foundation.org: update for futex-new-private-futexes]
[akpm@linux-foundation.org: build fix]
[jmorris@namei.org: lguest: use hrtimers]
[akpm@linux-foundation.org: x86_64 build fix]
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 236 insertions, 0 deletions

diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
new file mode 100644
index 000000000000..e90d7a783daf
--- /dev/null
+++ b/drivers/lguest/lguest_user.c
@@ -0,0 +1,236 @@
+/* Userspace control of the guest, via /dev/lguest. */
+#include <linux/uaccess.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include "lg.h"
+
+static void setup_regs(struct lguest_regs *regs, unsigned long start)
+{
+        /* Write out stack in format lguest expects, so we can switch to it. */
+        regs->ds = regs->es = regs->ss = __KERNEL_DS|GUEST_PL;
+        regs->cs = __KERNEL_CS|GUEST_PL;
+        regs->eflags = 0x202;   /* Interrupts enabled. */
+        regs->eip = start;
+        /* esi points to our boot information (physical address 0) */
+}
+
+/* + addr */
+static long user_get_dma(struct lguest *lg, const u32 __user *input)
+{
+        unsigned long key, udma, irq;
+
+        if (get_user(key, input) != 0)
+                return -EFAULT;
+        udma = get_dma_buffer(lg, key, &irq);
+        if (!udma)
+                return -ENOENT;
+
+        /* We put irq number in udma->used_len. */
+        lgwrite_u32(lg, udma + offsetof(struct lguest_dma, used_len), irq);
+        return udma;
+}
+
+/* To force the Guest to stop running and return to the Launcher, the
+ * Waker sets writes LHREQ_BREAK and the value "1" to /dev/lguest.  The
+ * Launcher then writes LHREQ_BREAK and "0" to release the Waker. */
+static int break_guest_out(struct lguest *lg, const u32 __user *input)
+{
+        unsigned long on;
+
+        /* Fetch whether they're turning break on or off.. */
+        if (get_user(on, input) != 0)
+                return -EFAULT;
+
+        if (on) {
+                lg->break_out = 1;
+                /* Pop it out (may be running on different CPU) */
+                wake_up_process(lg->tsk);
+                /* Wait for them to reset it */
+                return wait_event_interruptible(lg->break_wq, !lg->break_out);
+        } else {
+                lg->break_out = 0;
+                wake_up(&lg->break_wq);
+                return 0;
+        }
+}
+
+/* + irq */
+static int user_send_irq(struct lguest *lg, const u32 __user *input)
+{
+        u32 irq;
+
+        if (get_user(irq, input) != 0)
+                return -EFAULT;
+        if (irq >= LGUEST_IRQS)
+                return -EINVAL;
+        set_bit(irq, lg->irqs_pending);
+        return 0;
+}
+
+static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
+{
+        struct lguest *lg = file->private_data;
+
+        if (!lg)
+                return -EINVAL;
+
+        /* If you're not the task which owns the guest, go away. */
+        if (current != lg->tsk)
+                return -EPERM;
+
+        if (lg->dead) {
+                size_t len;
+
+                if (IS_ERR(lg->dead))
+                        return PTR_ERR(lg->dead);
+
+                len = min(size, strlen(lg->dead)+1);
+                if (copy_to_user(user, lg->dead, len) != 0)
+                        return -EFAULT;
+                return len;
+        }
+
+        if (lg->dma_is_pending)
+                lg->dma_is_pending = 0;
+
+        return run_guest(lg, (unsigned long __user *)user);
+}
+
+/* Take: pfnlimit, pgdir, start, pageoffset. */
+static int initialize(struct file *file, const u32 __user *input)
+{
+        struct lguest *lg;
+        int err, i;
+        u32 args[4];
+
+        /* We grab the Big Lguest lock, which protects the global array
+         * "lguests" and multiple simultaneous initializations. */
+        mutex_lock(&lguest_lock);
+
+        if (file->private_data) {
+                err = -EBUSY;
+                goto unlock;
+        }
+
+        if (copy_from_user(args, input, sizeof(args)) != 0) {
+                err = -EFAULT;
+                goto unlock;
+        }
+
+        i = find_free_guest();
+        if (i < 0) {
+                err = -ENOSPC;
+                goto unlock;
+        }
+        lg = &lguests[i];
+        lg->guestid = i;
+        lg->pfn_limit = args[0];
+        lg->page_offset = args[3];
+        lg->regs_page = get_zeroed_page(GFP_KERNEL);
+        if (!lg->regs_page) {
+                err = -ENOMEM;
+                goto release_guest;
+        }
+        lg->regs = (void *)lg->regs_page + PAGE_SIZE - sizeof(*lg->regs);
+
+        err = init_guest_pagetable(lg, args[1]);
+        if (err)
+                goto free_regs;
+
+        setup_regs(lg->regs, args[2]);
+        setup_guest_gdt(lg);
+        init_clockdev(lg);
+        lg->tsk = current;
+        lg->mm = get_task_mm(lg->tsk);
+        init_waitqueue_head(&lg->break_wq);
+        lg->last_pages = NULL;
+        file->private_data = lg;
+
+        mutex_unlock(&lguest_lock);
+
+        return sizeof(args);
+
+free_regs:
+        free_page(lg->regs_page);
+release_guest:
+        memset(lg, 0, sizeof(*lg));
+unlock:
+        mutex_unlock(&lguest_lock);
+        return err;
+}
+
+static ssize_t write(struct file *file, const char __user *input,
+                     size_t size, loff_t *off)
+{
+        struct lguest *lg = file->private_data;
+        u32 req;
+
+        if (get_user(req, input) != 0)
+                return -EFAULT;
+        input += sizeof(req);
+
+        if (req != LHREQ_INITIALIZE && !lg)
+                return -EINVAL;
+        if (lg && lg->dead)
+                return -ENOENT;
+
+        /* If you're not the task which owns the Guest, you can only break */
+        if (lg && current != lg->tsk && req != LHREQ_BREAK)
+                return -EPERM;
+
+        switch (req) {
+        case LHREQ_INITIALIZE:
+                return initialize(file, (const u32 __user *)input);
+        case LHREQ_GETDMA:
+                return user_get_dma(lg, (const u32 __user *)input);
+        case LHREQ_IRQ:
+                return user_send_irq(lg, (const u32 __user *)input);
+        case LHREQ_BREAK:
+                return break_guest_out(lg, (const u32 __user *)input);
+        default:
+                return -EINVAL;
+        }
+}
+
+static int close(struct inode *inode, struct file *file)
+{
+        struct lguest *lg = file->private_data;
+
+        if (!lg)
+                return 0;
+
+        mutex_lock(&lguest_lock);
+        /* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */
+        hrtimer_cancel(&lg->hrt);
+        release_all_dma(lg);
+        free_guest_pagetable(lg);
+        mmput(lg->mm);
+        if (!IS_ERR(lg->dead))
+                kfree(lg->dead);
+        free_page(lg->regs_page);
+        memset(lg, 0, sizeof(*lg));
+        mutex_unlock(&lguest_lock);
+        return 0;
+}
+
+static struct file_operations lguest_fops = {
+        .owner   = THIS_MODULE,
+        .release = close,
+        .write   = write,
+        .read    = read,
+};
+static struct miscdevice lguest_dev = {
+        .minor  = MISC_DYNAMIC_MINOR,
+        .name   = "lguest",
+        .fops   = &lguest_fops,
+};
+
+int __init lguest_device_init(void)
+{
+        return misc_register(&lguest_dev);
+}
+
+void __exit lguest_device_remove(void)
+{
+        misc_deregister(&lguest_dev);
+}