* controls and communicates with the Guest. For example, the first write will
* tell us the Guest's memory layout, pagetable, entry point and kernel address
* offset. A read will run the Guest until something happens, such as a signal
- * or the Guest doing a DMA out to the Launcher. Writes are also used to get a
- * DMA buffer registered by the Guest and to send the Guest an interrupt. :*/
+ * or the Guest doing a NOTIFY out to the Launcher. :*/
#include <linux/uaccess.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include "lg.h"
-/*L:310 To send DMA into the Guest, the Launcher needs to be able to ask for a
- * DMA buffer. This is done by writing LHREQ_GETDMA and the key to
- * /dev/lguest. */
-static long user_get_dma(struct lguest *lg, const unsigned long __user *input)
-{
- unsigned long key, udma, irq;
-
- /* Fetch the key they wrote to us. */
- if (get_user(key, input) != 0)
- return -EFAULT;
- /* Look for a free Guest DMA buffer bound to that key. */
- udma = get_dma_buffer(lg, key, &irq);
- if (!udma)
- return -ENOENT;
-
- /* We need to tell the Launcher what interrupt the Guest expects after
- * the buffer is filled. We stash it in udma->used_len. */
- lgwrite_u32(lg, udma + offsetof(struct lguest_dma, used_len), irq);
-
- /* The (guest-physical) address of the DMA buffer is returned from
- * the write(). */
- return udma;
-}
-
-/*L:315 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. */
+/*L:055 When something happens, the Waker process needs a way to stop the
+ * kernel running the Guest and return to the Launcher. So the Waker writes
+ * LHREQ_BREAK and the value "1" to /dev/lguest to do this. Once the Launcher
+ * has done whatever needs attention, it writes LHREQ_BREAK and "0" to release
+ * the Waker. */
static int break_guest_out(struct lguest *lg, const unsigned long __user *input)
{
unsigned long on;
- /* Fetch whether they're turning break on or off.. */
+ /* 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) */
+ /* Pop it out of the Guest (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);
if (!lg)
return -EINVAL;
- /* If you're not the task which owns the guest, go away. */
+ /* If you're not the task which owns the Guest, go away. */
if (current != lg->tsk)
return -EPERM;
return len;
}
- /* If we returned from read() last time because the Guest sent DMA,
+ /* If we returned from read() last time because the Guest notified,
* clear the flag. */
- if (lg->dma_is_pending)
- lg->dma_is_pending = 0;
+ if (lg->pending_notify)
+ lg->pending_notify = 0;
/* Run the Guest until something interesting happens. */
return run_guest(lg, (unsigned long __user *)user);
}
-/*L:020 The initialization write supplies 5 pointer sized (32 or 64 bit)
+/*L:020 The initialization write supplies 4 pointer sized (32 or 64 bit)
* values (in addition to the LHREQ_INITIALIZE value). These are:
*
* base: The start of the Guest-physical memory inside the Launcher memory.
*
* pfnlimit: The highest (Guest-physical) page number the Guest should be
- * allowed to access. The Launcher has to live in Guest memory, so it sets
- * this to ensure the Guest can't reach it.
+ * allowed to access. The Guest memory lives inside the Launcher, so it sets
+ * this to ensure the Guest can only reach its own memory.
*
* pgdir: The (Guest-physical) address of the top of the initial Guest
* pagetables (which are set up by the Launcher).
*
* start: The first instruction to execute ("eip" in x86-speak).
- *
- * page_offset: The PAGE_OFFSET constant in the Guest kernel. We should
- * probably wean the code off this, but it's a very useful constant! Any
- * address above this is within the Guest kernel, and any kernel address can
- * quickly converted from physical to virtual by adding PAGE_OFFSET. It's
- * 0xC0000000 (3G) by default, but it's configurable at kernel build time.
*/
static int initialize(struct file *file, const unsigned long __user *input)
{
* Guest. */
struct lguest *lg;
int err;
- unsigned long args[5];
+ unsigned long args[4];
/* We grab the Big Lguest lock, which protects against multiple
* simultaneous initializations. */
/* Populate the easy fields of our "struct lguest" */
lg->mem_base = (void __user *)(long)args[0];
lg->pfn_limit = args[1];
- lg->page_offset = args[4];
/* We need a complete page for the Guest registers: they are accessible
* to the Guest and we can only grant it access to whole pages. */
}
/*L:010 The first operation the Launcher does must be a write. All writes
- * start with a 32 bit number: for the first write this must be
+ * start with an unsigned long number: for the first write this must be
* LHREQ_INITIALIZE to set up the Guest. After that the Launcher can use
- * writes of other values to get DMA buffers and send interrupts. */
+ * writes of other values to send interrupts. */
static ssize_t write(struct file *file, const char __user *in,
size_t size, loff_t *off)
{
switch (req) {
case LHREQ_INITIALIZE:
return initialize(file, input);
- case LHREQ_GETDMA:
- return user_get_dma(lg, input);
case LHREQ_IRQ:
return user_send_irq(lg, input);
case LHREQ_BREAK:
mutex_lock(&lguest_lock);
/* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */
hrtimer_cancel(&lg->hrt);
- /* Free any DMA buffers the Guest had bound. */
- release_all_dma(lg);
/* Free up the shadow page tables for the Guest. */
free_guest_pagetable(lg);
/* Now all the memory cleanups are done, it's safe to release the
* The Launcher is the Host userspace program which sets up, runs and services
* the Guest. In fact, many comments in the Drivers which refer to "the Host"
* doing things are inaccurate: the Launcher does all the device handling for
- * the Guest. The Guest can't tell what's done by the the Launcher and what by
- * the Host.
+ * the Guest, but the Guest can't know that.
*
* Just to confuse you: to the Host kernel, the Launcher *is* the Guest and we
* shall see more of that later.
git.samba.org / sfrench / cifs-2.6.git / blobdiff