diff options
Diffstat (limited to 'drivers/lguest/lguest_user.c')
-rw-r--r-- | drivers/lguest/lguest_user.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c index ee405b38383d..9d716fa42cad 100644 --- a/drivers/lguest/lguest_user.c +++ b/drivers/lguest/lguest_user.c | |||
@@ -8,20 +8,22 @@ | |||
8 | #include <linux/fs.h> | 8 | #include <linux/fs.h> |
9 | #include "lg.h" | 9 | #include "lg.h" |
10 | 10 | ||
11 | /*L:315 To force the Guest to stop running and return to the Launcher, the | 11 | /*L:055 When something happens, the Waker process needs a way to stop the |
12 | * Waker sets writes LHREQ_BREAK and the value "1" to /dev/lguest. The | 12 | * kernel running the Guest and return to the Launcher. So the Waker writes |
13 | * Launcher then writes LHREQ_BREAK and "0" to release the Waker. */ | 13 | * LHREQ_BREAK and the value "1" to /dev/lguest to do this. Once the Launcher |
14 | * has done whatever needs attention, it writes LHREQ_BREAK and "0" to release | ||
15 | * the Waker. */ | ||
14 | static int break_guest_out(struct lguest *lg, const unsigned long __user *input) | 16 | static int break_guest_out(struct lguest *lg, const unsigned long __user *input) |
15 | { | 17 | { |
16 | unsigned long on; | 18 | unsigned long on; |
17 | 19 | ||
18 | /* Fetch whether they're turning break on or off.. */ | 20 | /* Fetch whether they're turning break on or off. */ |
19 | if (get_user(on, input) != 0) | 21 | if (get_user(on, input) != 0) |
20 | return -EFAULT; | 22 | return -EFAULT; |
21 | 23 | ||
22 | if (on) { | 24 | if (on) { |
23 | lg->break_out = 1; | 25 | lg->break_out = 1; |
24 | /* Pop it out (may be running on different CPU) */ | 26 | /* Pop it out of the Guest (may be running on different CPU) */ |
25 | wake_up_process(lg->tsk); | 27 | wake_up_process(lg->tsk); |
26 | /* Wait for them to reset it */ | 28 | /* Wait for them to reset it */ |
27 | return wait_event_interruptible(lg->break_wq, !lg->break_out); | 29 | return wait_event_interruptible(lg->break_wq, !lg->break_out); |
@@ -58,7 +60,7 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o) | |||
58 | if (!lg) | 60 | if (!lg) |
59 | return -EINVAL; | 61 | return -EINVAL; |
60 | 62 | ||
61 | /* If you're not the task which owns the guest, go away. */ | 63 | /* If you're not the task which owns the Guest, go away. */ |
62 | if (current != lg->tsk) | 64 | if (current != lg->tsk) |
63 | return -EPERM; | 65 | return -EPERM; |
64 | 66 | ||
@@ -92,8 +94,8 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o) | |||
92 | * base: The start of the Guest-physical memory inside the Launcher memory. | 94 | * base: The start of the Guest-physical memory inside the Launcher memory. |
93 | * | 95 | * |
94 | * pfnlimit: The highest (Guest-physical) page number the Guest should be | 96 | * pfnlimit: The highest (Guest-physical) page number the Guest should be |
95 | * allowed to access. The Launcher has to live in Guest memory, so it sets | 97 | * allowed to access. The Guest memory lives inside the Launcher, so it sets |
96 | * this to ensure the Guest can't reach it. | 98 | * this to ensure the Guest can only reach its own memory. |
97 | * | 99 | * |
98 | * pgdir: The (Guest-physical) address of the top of the initial Guest | 100 | * pgdir: The (Guest-physical) address of the top of the initial Guest |
99 | * pagetables (which are set up by the Launcher). | 101 | * pagetables (which are set up by the Launcher). |
@@ -189,7 +191,7 @@ unlock: | |||
189 | } | 191 | } |
190 | 192 | ||
191 | /*L:010 The first operation the Launcher does must be a write. All writes | 193 | /*L:010 The first operation the Launcher does must be a write. All writes |
192 | * start with a 32 bit number: for the first write this must be | 194 | * start with an unsigned long number: for the first write this must be |
193 | * LHREQ_INITIALIZE to set up the Guest. After that the Launcher can use | 195 | * LHREQ_INITIALIZE to set up the Guest. After that the Launcher can use |
194 | * writes of other values to send interrupts. */ | 196 | * writes of other values to send interrupts. */ |
195 | static ssize_t write(struct file *file, const char __user *in, | 197 | static ssize_t write(struct file *file, const char __user *in, |
@@ -275,8 +277,7 @@ static int close(struct inode *inode, struct file *file) | |||
275 | * The Launcher is the Host userspace program which sets up, runs and services | 277 | * The Launcher is the Host userspace program which sets up, runs and services |
276 | * the Guest. In fact, many comments in the Drivers which refer to "the Host" | 278 | * the Guest. In fact, many comments in the Drivers which refer to "the Host" |
277 | * doing things are inaccurate: the Launcher does all the device handling for | 279 | * doing things are inaccurate: the Launcher does all the device handling for |
278 | * the Guest. The Guest can't tell what's done by the the Launcher and what by | 280 | * the Guest, but the Guest can't know that. |
279 | * the Host. | ||
280 | * | 281 | * |
281 | * Just to confuse you: to the Host kernel, the Launcher *is* the Guest and we | 282 | * Just to confuse you: to the Host kernel, the Launcher *is* the Guest and we |
282 | * shall see more of that later. | 283 | * shall see more of that later. |