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authorRusty Russell <rusty@rustcorp.com.au>2007-10-21 21:24:10 -0400
committerRusty Russell <rusty@rustcorp.com.au>2007-10-23 01:49:55 -0400
commit15045275c32bf6d15d32c2eca8157be9c0ba6e45 (patch)
tree32ef90c875b22cb1bbb94e38f557a690f1c0c6f8 /drivers
parent0ca49ca946409f87a8cd0b14d5acb6dea58de6f3 (diff)
Remove old lguest I/O infrrasructure.
This patch gets rid of the old lguest host I/O infrastructure and replaces it with a single hypercall "LHCALL_NOTIFY" which takes an address. The main change is the removal of io.c: that mainly did inter-guest I/O, which virtio doesn't yet support. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/lguest/Makefile2
-rw-r--r--drivers/lguest/core.c12
-rw-r--r--drivers/lguest/hypercalls.c26
-rw-r--r--drivers/lguest/io.c628
-rw-r--r--drivers/lguest/lg.h27
-rw-r--r--drivers/lguest/lguest_user.c39
6 files changed, 19 insertions, 715 deletions
diff --git a/drivers/lguest/Makefile b/drivers/lguest/Makefile
index 8c28236ee1a..a63f75dc41a 100644
--- a/drivers/lguest/Makefile
+++ b/drivers/lguest/Makefile
@@ -1,7 +1,7 @@
1# Host requires the other files, which can be a module. 1# Host requires the other files, which can be a module.
2obj-$(CONFIG_LGUEST) += lg.o 2obj-$(CONFIG_LGUEST) += lg.o
3lg-y = core.o hypercalls.o page_tables.o interrupts_and_traps.o \ 3lg-y = core.o hypercalls.o page_tables.o interrupts_and_traps.o \
4 segments.o io.o lguest_user.o 4 segments.o lguest_user.o
5 5
6lg-$(CONFIG_X86_32) += x86/switcher_32.o x86/core.o 6lg-$(CONFIG_X86_32) += x86/switcher_32.o x86/core.o
7 7
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index 41b26e592d3..3aec29ec771 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -202,13 +202,12 @@ int run_guest(struct lguest *lg, unsigned long __user *user)
202 if (lg->hcall) 202 if (lg->hcall)
203 do_hypercalls(lg); 203 do_hypercalls(lg);
204 204
205 /* It's possible the Guest did a SEND_DMA hypercall to the 205 /* It's possible the Guest did a NOTIFY hypercall to the
206 * Launcher, in which case we return from the read() now. */ 206 * Launcher, in which case we return from the read() now. */
207 if (lg->dma_is_pending) { 207 if (lg->pending_notify) {
208 if (put_user(lg->pending_dma, user) || 208 if (put_user(lg->pending_notify, user))
209 put_user(lg->pending_key, user+1))
210 return -EFAULT; 209 return -EFAULT;
211 return sizeof(unsigned long)*2; 210 return sizeof(lg->pending_notify);
212 } 211 }
213 212
214 /* Check for signals */ 213 /* Check for signals */
@@ -288,9 +287,6 @@ static int __init init(void)
288 if (err) 287 if (err)
289 goto unmap; 288 goto unmap;
290 289
291 /* The I/O subsystem needs some things initialized. */
292 lguest_io_init();
293
294 /* We might need to reserve an interrupt vector. */ 290 /* We might need to reserve an interrupt vector. */
295 err = init_interrupts(); 291 err = init_interrupts();
296 if (err) 292 if (err)
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
index 13b5f2f813d..3a53788ba45 100644
--- a/drivers/lguest/hypercalls.c
+++ b/drivers/lguest/hypercalls.c
@@ -60,22 +60,9 @@ static void do_hcall(struct lguest *lg, struct hcall_args *args)
60 else 60 else
61 guest_pagetable_flush_user(lg); 61 guest_pagetable_flush_user(lg);
62 break; 62 break;
63 case LHCALL_BIND_DMA:
64 /* BIND_DMA really wants four arguments, but it's the only call
65 * which does. So the Guest packs the number of buffers and
66 * the interrupt number into the final argument, and we decode
67 * it here. This can legitimately fail, since we currently
68 * place a limit on the number of DMA pools a Guest can have.
69 * So we return true or false from this call. */
70 args->arg0 = bind_dma(lg, args->arg1, args->arg2,
71 args->arg3 >> 8, args->arg3 & 0xFF);
72 break;
73 63
74 /* All these calls simply pass the arguments through to the right 64 /* All these calls simply pass the arguments through to the right
75 * routines. */ 65 * routines. */
76 case LHCALL_SEND_DMA:
77 send_dma(lg, args->arg1, args->arg2);
78 break;
79 case LHCALL_NEW_PGTABLE: 66 case LHCALL_NEW_PGTABLE:
80 guest_new_pagetable(lg, args->arg1); 67 guest_new_pagetable(lg, args->arg1);
81 break; 68 break;
@@ -99,6 +86,9 @@ static void do_hcall(struct lguest *lg, struct hcall_args *args)
99 /* Similarly, this sets the halted flag for run_guest(). */ 86 /* Similarly, this sets the halted flag for run_guest(). */
100 lg->halted = 1; 87 lg->halted = 1;
101 break; 88 break;
89 case LHCALL_NOTIFY:
90 lg->pending_notify = args->arg1;
91 break;
102 default: 92 default:
103 if (lguest_arch_do_hcall(lg, args)) 93 if (lguest_arch_do_hcall(lg, args))
104 kill_guest(lg, "Bad hypercall %li\n", args->arg0); 94 kill_guest(lg, "Bad hypercall %li\n", args->arg0);
@@ -156,9 +146,9 @@ static void do_async_hcalls(struct lguest *lg)
156 break; 146 break;
157 } 147 }
158 148
159 /* Stop doing hypercalls if we've just done a DMA to the 149 /* Stop doing hypercalls if they want to notify the Launcher:
160 * Launcher: it needs to service this first. */ 150 * it needs to service this first. */
161 if (lg->dma_is_pending) 151 if (lg->pending_notify)
162 break; 152 break;
163 } 153 }
164} 154}
@@ -220,9 +210,9 @@ void do_hypercalls(struct lguest *lg)
220 do_async_hcalls(lg); 210 do_async_hcalls(lg);
221 211
222 /* If we stopped reading the hypercall ring because the Guest did a 212 /* If we stopped reading the hypercall ring because the Guest did a
223 * SEND_DMA to the Launcher, we want to return now. Otherwise we do 213 * NOTIFY to the Launcher, we want to return now. Otherwise we do
224 * the hypercall. */ 214 * the hypercall. */
225 if (!lg->dma_is_pending) { 215 if (!lg->pending_notify) {
226 do_hcall(lg, lg->hcall); 216 do_hcall(lg, lg->hcall);
227 /* Tricky point: we reset the hcall pointer to mark the 217 /* Tricky point: we reset the hcall pointer to mark the
228 * hypercall as "done". We use the hcall pointer rather than 218 * hypercall as "done". We use the hcall pointer rather than
diff --git a/drivers/lguest/io.c b/drivers/lguest/io.c
deleted file mode 100644
index 0e842e9caf6..00000000000
--- a/drivers/lguest/io.c
+++ /dev/null
@@ -1,628 +0,0 @@
1/*P:300 The I/O mechanism in lguest is simple yet flexible, allowing the Guest
2 * to talk to the Launcher or directly to another Guest. It uses familiar
3 * concepts of DMA and interrupts, plus some neat code stolen from
4 * futexes... :*/
5
6/* Copyright (C) 2006 Rusty Russell IBM Corporation
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22#include <linux/types.h>
23#include <linux/futex.h>
24#include <linux/jhash.h>
25#include <linux/mm.h>
26#include <linux/highmem.h>
27#include <linux/uaccess.h>
28#include "lg.h"
29
30/*L:300
31 * I/O
32 *
33 * Getting data in and out of the Guest is quite an art. There are numerous
34 * ways to do it, and they all suck differently. We try to keep things fairly
35 * close to "real" hardware so our Guest's drivers don't look like an alien
36 * visitation in the middle of the Linux code, and yet make sure that Guests
37 * can talk directly to other Guests, not just the Launcher.
38 *
39 * To do this, the Guest gives us a key when it binds or sends DMA buffers.
40 * The key corresponds to a "physical" address inside the Guest (ie. a virtual
41 * address inside the Launcher process). We don't, however, use this key
42 * directly.
43 *
44 * We want Guests which share memory to be able to DMA to each other: two
45 * Launchers can mmap memory the same file, then the Guests can communicate.
46 * Fortunately, the futex code provides us with a way to get a "union
47 * futex_key" corresponding to the memory lying at a virtual address: if the
48 * two processes share memory, the "union futex_key" for that memory will match
49 * even if the memory is mapped at different addresses in each. So we always
50 * convert the keys to "union futex_key"s to compare them.
51 *
52 * Before we dive into this though, we need to look at another set of helper
53 * routines used throughout the Host kernel code to access Guest memory.
54 :*/
55static struct list_head dma_hash[61];
56
57/* An unfortunate side effect of the Linux double-linked list implementation is
58 * that there's no good way to statically initialize an array of linked
59 * lists. */
60void lguest_io_init(void)
61{
62 unsigned int i;
63
64 for (i = 0; i < ARRAY_SIZE(dma_hash); i++)
65 INIT_LIST_HEAD(&dma_hash[i]);
66}
67
68/* FIXME: allow multi-page lengths. */
69static int check_dma_list(struct lguest *lg, const struct lguest_dma *dma)
70{
71 unsigned int i;
72
73 for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
74 if (!dma->len[i])
75 return 1;
76 if (!lguest_address_ok(lg, dma->addr[i], dma->len[i]))
77 goto kill;
78 if (dma->len[i] > PAGE_SIZE)
79 goto kill;
80 /* We could do over a page, but is it worth it? */
81 if ((dma->addr[i] % PAGE_SIZE) + dma->len[i] > PAGE_SIZE)
82 goto kill;
83 }
84 return 1;
85
86kill:
87 kill_guest(lg, "bad DMA entry: %u@%#lx", dma->len[i], dma->addr[i]);
88 return 0;
89}
90
91/*L:330 This is our hash function, using the wonderful Jenkins hash.
92 *
93 * The futex key is a union with three parts: an unsigned long word, a pointer,
94 * and an int "offset". We could use jhash_2words() which takes three u32s.
95 * (Ok, the hash functions are great: the naming sucks though).
96 *
97 * It's nice to be portable to 64-bit platforms, so we use the more generic
98 * jhash2(), which takes an array of u32, the number of u32s, and an initial
99 * u32 to roll in. This is uglier, but breaks down to almost the same code on
100 * 32-bit platforms like this one.
101 *
102 * We want a position in the array, so we modulo ARRAY_SIZE(dma_hash) (ie. 61).
103 */
104static unsigned int hash(const union futex_key *key)
105{
106 return jhash2((u32*)&key->both.word,
107 (sizeof(key->both.word)+sizeof(key->both.ptr))/4,
108 key->both.offset)
109 % ARRAY_SIZE(dma_hash);
110}
111
112/* This is a convenience routine to compare two keys. It's a much bemoaned C
113 * weakness that it doesn't allow '==' on structures or unions, so we have to
114 * open-code it like this. */
115static inline int key_eq(const union futex_key *a, const union futex_key *b)
116{
117 return (a->both.word == b->both.word
118 && a->both.ptr == b->both.ptr
119 && a->both.offset == b->both.offset);
120}
121
122/*L:360 OK, when we need to actually free up a Guest's DMA array we do several
123 * things, so we have a convenient function to do it.
124 *
125 * The caller must hold a read lock on dmainfo owner's current->mm->mmap_sem
126 * for the drop_futex_key_refs(). */
127static void unlink_dma(struct lguest_dma_info *dmainfo)
128{
129 /* You locked this too, right? */
130 BUG_ON(!mutex_is_locked(&lguest_lock));
131 /* This is how we know that the entry is free. */
132 dmainfo->interrupt = 0;
133 /* Remove it from the hash table. */
134 list_del(&dmainfo->list);
135 /* Drop the references we were holding (to the inode or mm). */
136 drop_futex_key_refs(&dmainfo->key);
137}
138
139/*L:350 This is the routine which we call when the Guest asks to unregister a
140 * DMA array attached to a given key. Returns true if the array was found. */
141static int unbind_dma(struct lguest *lg,
142 const union futex_key *key,
143 unsigned long dmas)
144{
145 int i, ret = 0;
146
147 /* We don't bother with the hash table, just look through all this
148 * Guest's DMA arrays. */
149 for (i = 0; i < LGUEST_MAX_DMA; i++) {
150 /* In theory it could have more than one array on the same key,
151 * or one array on multiple keys, so we check both */
152 if (key_eq(key, &lg->dma[i].key) && dmas == lg->dma[i].dmas) {
153 unlink_dma(&lg->dma[i]);
154 ret = 1;
155 break;
156 }
157 }
158 return ret;
159}
160
161/*L:340 BIND_DMA: this is the hypercall which sets up an array of "struct
162 * lguest_dma" for receiving I/O.
163 *
164 * The Guest wants to bind an array of "struct lguest_dma"s to a particular key
165 * to receive input. This only happens when the Guest is setting up a new
166 * device, so it doesn't have to be very fast.
167 *
168 * It returns 1 on a successful registration (it can fail if we hit the limit
169 * of registrations for this Guest).
170 */
171int bind_dma(struct lguest *lg,
172 unsigned long ukey, unsigned long dmas, u16 numdmas, u8 interrupt)
173{
174 unsigned int i;
175 int ret = 0;
176 union futex_key key;
177 /* Futex code needs the mmap_sem. */
178 struct rw_semaphore *fshared = &current->mm->mmap_sem;
179
180 /* Invalid interrupt? (We could kill the guest here). */
181 if (interrupt >= LGUEST_IRQS)
182 return 0;
183
184 /* We need to grab the Big Lguest Lock, because other Guests may be
185 * trying to look through this Guest's DMAs to send something while
186 * we're doing this. */
187 mutex_lock(&lguest_lock);
188 down_read(fshared);
189 if (get_futex_key(lg->mem_base + ukey, fshared, &key) != 0) {
190 kill_guest(lg, "bad dma key %#lx", ukey);
191 goto unlock;
192 }
193
194 /* We want to keep this key valid once we drop mmap_sem, so we have to
195 * hold a reference. */
196 get_futex_key_refs(&key);
197
198 /* If the Guest specified an interrupt of 0, that means they want to
199 * unregister this array of "struct lguest_dma"s. */
200 if (interrupt == 0)
201 ret = unbind_dma(lg, &key, dmas);
202 else {
203 /* Look through this Guest's dma array for an unused entry. */
204 for (i = 0; i < LGUEST_MAX_DMA; i++) {
205 /* If the interrupt is non-zero, the entry is already
206 * used. */
207 if (lg->dma[i].interrupt)
208 continue;
209
210 /* OK, a free one! Fill on our details. */
211 lg->dma[i].dmas = dmas;
212 lg->dma[i].num_dmas = numdmas;
213 lg->dma[i].next_dma = 0;
214 lg->dma[i].key = key;
215 lg->dma[i].owner = lg;
216 lg->dma[i].interrupt = interrupt;
217
218 /* Now we add it to the hash table: the position
219 * depends on the futex key that we got. */
220 list_add(&lg->dma[i].list, &dma_hash[hash(&key)]);
221 /* Success! */
222 ret = 1;
223 goto unlock;
224 }
225 }
226 /* If we didn't find a slot to put the key in, drop the reference
227 * again. */
228 drop_futex_key_refs(&key);
229unlock:
230 /* Unlock and out. */
231 up_read(fshared);
232 mutex_unlock(&lguest_lock);
233 return ret;
234}
235
236/*L:385 Note that our routines to access a different Guest's memory are called
237 * lgread_other() and lgwrite_other(): these names emphasize that they are only
238 * used when the Guest is *not* the current Guest.
239 *
240 * The interface for copying from another process's memory is called
241 * access_process_vm(), with a final argument of 0 for a read, and 1 for a
242 * write.
243 *
244 * We need lgread_other() to read the destination Guest's "struct lguest_dma"
245 * array. */
246static int lgread_other(struct lguest *lg,
247 void *buf, u32 addr, unsigned bytes)
248{
249 if (!lguest_address_ok(lg, addr, bytes)
250 || access_process_vm(lg->tsk, (unsigned long)lg->mem_base + addr,
251 buf, bytes, 0) != bytes) {
252 memset(buf, 0, bytes);
253 kill_guest(lg, "bad address in registered DMA struct");
254 return 0;
255 }
256 return 1;
257}
258
259/* "lgwrite()" to another Guest: used to update the destination "used_len" once
260 * we've transferred data into the buffer. */
261static int lgwrite_other(struct lguest *lg, u32 addr,
262 const void *buf, unsigned bytes)
263{
264 if (!lguest_address_ok(lg, addr, bytes)
265 || access_process_vm(lg->tsk, (unsigned long)lg->mem_base + addr,
266 (void *)buf, bytes, 1) != bytes) {
267 kill_guest(lg, "bad address writing to registered DMA");
268 return 0;
269 }
270 return 1;
271}
272
273/*L:400 This is the generic engine which copies from a source "struct
274 * lguest_dma" from this Guest into another Guest's "struct lguest_dma". The
275 * destination Guest's pages have already been mapped, as contained in the
276 * pages array.
277 *
278 * If you're wondering if there's a nice "copy from one process to another"
279 * routine, so was I. But Linux isn't really set up to copy between two
280 * unrelated processes, so we have to write it ourselves.
281 */
282static u32 copy_data(struct lguest *srclg,
283 const struct lguest_dma *src,
284 const struct lguest_dma *dst,
285 struct page *pages[])
286{
287 unsigned int totlen, si, di, srcoff, dstoff;
288 void *maddr = NULL;
289
290 /* We return the total length transferred. */
291 totlen = 0;
292
293 /* We keep indexes into the source and destination "struct lguest_dma",
294 * and an offset within each region. */
295 si = di = 0;
296 srcoff = dstoff = 0;
297
298 /* We loop until the source or destination is exhausted. */
299 while (si < LGUEST_MAX_DMA_SECTIONS && src->len[si]
300 && di < LGUEST_MAX_DMA_SECTIONS && dst->len[di]) {
301 /* We can only transfer the rest of the src buffer, or as much
302 * as will fit into the destination buffer. */
303 u32 len = min(src->len[si] - srcoff, dst->len[di] - dstoff);
304
305 /* For systems using "highmem" we need to use kmap() to access
306 * the page we want. We often use the same page over and over,
307 * so rather than kmap() it on every loop, we set the maddr
308 * pointer to NULL when we need to move to the next
309 * destination page. */
310 if (!maddr)
311 maddr = kmap(pages[di]);
312
313 /* Copy directly from (this Guest's) source address to the
314 * destination Guest's kmap()ed buffer. Note that maddr points
315 * to the start of the page: we need to add the offset of the
316 * destination address and offset within the buffer. */
317
318 /* FIXME: This is not completely portable. I looked at
319 * copy_to_user_page(), and some arch's seem to need special
320 * flushes. x86 is fine. */
321 if (copy_from_user(maddr + (dst->addr[di] + dstoff)%PAGE_SIZE,
322 srclg->mem_base+src->addr[si], len) != 0) {
323 /* If a copy failed, it's the source's fault. */
324 kill_guest(srclg, "bad address in sending DMA");
325 totlen = 0;
326 break;
327 }
328
329 /* Increment the total and src & dst offsets */
330 totlen += len;
331 srcoff += len;
332 dstoff += len;
333
334 /* Presumably we reached the end of the src or dest buffers: */
335 if (srcoff == src->len[si]) {
336 /* Move to the next buffer at offset 0 */
337 si++;
338 srcoff = 0;
339 }
340 if (dstoff == dst->len[di]) {
341 /* We need to unmap that destination page and reset
342 * maddr ready for the next one. */
343 kunmap(pages[di]);
344 maddr = NULL;
345 di++;
346 dstoff = 0;
347 }
348 }
349
350 /* If we still had a page mapped at the end, unmap now. */
351 if (maddr)
352 kunmap(pages[di]);
353
354 return totlen;
355}
356
357/*L:390 This is how we transfer a "struct lguest_dma" from the source Guest
358 * (the current Guest which called SEND_DMA) to another Guest. */
359static u32 do_dma(struct lguest *srclg, const struct lguest_dma *src,
360 struct lguest *dstlg, const struct lguest_dma *dst)
361{
362 int i;
363 u32 ret;
364 struct page *pages[LGUEST_MAX_DMA_SECTIONS];
365
366 /* We check that both source and destination "struct lguest_dma"s are
367 * within the bounds of the source and destination Guests */
368 if (!check_dma_list(dstlg, dst) || !check_dma_list(srclg, src))
369 return 0;
370
371 /* We need to map the pages which correspond to each parts of
372 * destination buffer. */
373 for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
374 if (dst->len[i] == 0)
375 break;
376 /* get_user_pages() is a complicated function, especially since
377 * we only want a single page. But it works, and returns the
378 * number of pages. Note that we're holding the destination's
379 * mmap_sem, as get_user_pages() requires. */
380 if (get_user_pages(dstlg->tsk, dstlg->mm,
381 (unsigned long)dstlg->mem_base+dst->addr[i],
382 1, 1, 1, pages+i, NULL)
383 != 1) {
384 /* This means the destination gave us a bogus buffer */
385 kill_guest(dstlg, "Error mapping DMA pages");
386 ret = 0;
387 goto drop_pages;
388 }
389 }
390
391 /* Now copy the data until we run out of src or dst. */
392 ret = copy_data(srclg, src, dst, pages);
393
394drop_pages:
395 while (--i >= 0)
396 put_page(pages[i]);
397 return ret;
398}
399
400/*L:380 Transferring data from one Guest to another is not as simple as I'd
401 * like. We've found the "struct lguest_dma_info" bound to the same address as
402 * the send, we need to copy into it.
403 *
404 * This function returns true if the destination array was empty. */
405static int dma_transfer(struct lguest *srclg,
406 unsigned long udma,
407 struct lguest_dma_info *dst)
408{
409 struct lguest_dma dst_dma, src_dma;
410 struct lguest *dstlg;
411 u32 i, dma = 0;
412
413 /* From the "struct lguest_dma_info" we found in the hash, grab the
414 * Guest. */
415 dstlg = dst->owner;
416 /* Read in the source "struct lguest_dma" handed to SEND_DMA. */
417 lgread(srclg, &src_dma, udma, sizeof(src_dma));
418
419 /* We need the destination's mmap_sem, and we already hold the source's
420 * mmap_sem for the futex key lookup. Normally this would suggest that
421 * we could deadlock if the destination Guest was trying to send to
422 * this source Guest at the same time, which is another reason that all
423 * I/O is done under the big lguest_lock. */
424 down_read(&dstlg->mm->mmap_sem);
425
426 /* Look through the destination DMA array for an available buffer. */
427 for (i = 0; i < dst->num_dmas; i++) {
428 /* We keep a "next_dma" pointer which often helps us avoid
429 * looking at lots of previously-filled entries. */
430 dma = (dst->next_dma + i) % dst->num_dmas;
431 if (!lgread_other(dstlg, &dst_dma,
432 dst->dmas + dma * sizeof(struct lguest_dma),
433 sizeof(dst_dma))) {
434 goto fail;
435 }
436 if (!dst_dma.used_len)
437 break;
438 }
439
440 /* If we found a buffer, we do the actual data copy. */
441 if (i != dst->num_dmas) {
442 unsigned long used_lenp;
443 unsigned int ret;
444
445 ret = do_dma(srclg, &src_dma, dstlg, &dst_dma);
446 /* Put used length in the source "struct lguest_dma"'s used_len
447 * field. It's a little tricky to figure out where that is,
448 * though. */
449 lgwrite_u32(srclg,
450 udma+offsetof(struct lguest_dma, used_len), ret);
451 /* Tranferring 0 bytes is OK if the source buffer was empty. */
452 if (ret == 0 && src_dma.len[0] != 0)
453 goto fail;
454
455 /* The destination Guest might be running on a different CPU:
456 * we have to make sure that it will see the "used_len" field
457 * change to non-zero *after* it sees the data we copied into
458 * the buffer. Hence a write memory barrier. */
459 wmb();
460 /* Figuring out where the destination's used_len field for this
461 * "struct lguest_dma" in the array is also a little ugly. */
462 used_lenp = dst->dmas
463 + dma * sizeof(struct lguest_dma)
464 + offsetof(struct lguest_dma, used_len);
465 lgwrite_other(dstlg, used_lenp, &ret, sizeof(ret));
466 /* Move the cursor for next time. */
467 dst->next_dma++;
468 }
469 up_read(&dstlg->mm->mmap_sem);
470
471 /* We trigger the destination interrupt, even if the destination was
472 * empty and we didn't transfer anything: this gives them a chance to
473 * wake up and refill. */
474 set_bit(dst->interrupt, dstlg->irqs_pending);
475 /* Wake up the destination process. */
476 wake_up_process(dstlg->tsk);
477 /* If we passed the last "struct lguest_dma", the receive had no
478 * buffers left. */
479 return i == dst->num_dmas;
480
481fail:
482 up_read(&dstlg->mm->mmap_sem);
483 return 0;
484}
485
486/*L:370 This is the counter-side to the BIND_DMA hypercall; the SEND_DMA
487 * hypercall. We find out who's listening, and send to them. */
488void send_dma(struct lguest *lg, unsigned long ukey, unsigned long udma)
489{
490 union futex_key key;
491 int empty = 0;
492 struct rw_semaphore *fshared = &current->mm->mmap_sem;
493
494again:
495 mutex_lock(&lguest_lock);
496 down_read(fshared);
497 /* Get the futex key for the key the Guest gave us */
498 if (get_futex_key(lg->mem_base + ukey, fshared, &key) != 0) {
499 kill_guest(lg, "bad sending DMA key");
500 goto unlock;
501 }
502 /* Since the key must be a multiple of 4, the futex key uses the lower
503 * bit of the "offset" field (which would always be 0) to indicate a
504 * mapping which is shared with other processes (ie. Guests). */
505 if (key.shared.offset & 1) {
506 struct lguest_dma_info *i;
507 /* Look through the hash for other Guests. */
508 list_for_each_entry(i, &dma_hash[hash(&key)], list) {
509 /* Don't send to ourselves (would deadlock). */
510 if (i->owner->mm == lg->mm)
511 continue;
512 if (!key_eq(&key, &i->key))
513 continue;
514
515 /* If dma_transfer() tells us the destination has no
516 * available buffers, we increment "empty". */
517 empty += dma_transfer(lg, udma, i);
518 break;
519 }
520 /* If the destination is empty, we release our locks and
521 * give the destination Guest a brief chance to restock. */
522 if (empty == 1) {
523 /* Give any recipients one chance to restock. */
524 up_read(&current->mm->mmap_sem);
525 mutex_unlock(&lguest_lock);
526 /* Next time, we won't try again. */
527 empty++;
528 goto again;
529 }
530 } else {
531 /* Private mapping: Guest is sending to its Launcher. We set
532 * the "dma_is_pending" flag so that the main loop will exit
533 * and the Launcher's read() from /dev/lguest will return. */
534 lg->dma_is_pending = 1;
535 lg->pending_dma = udma;
536 lg->pending_key = ukey;
537 }
538unlock:
539 up_read(fshared);
540 mutex_unlock(&lguest_lock);
541}
542/*:*/
543
544void release_all_dma(struct lguest *lg)
545{
546 unsigned int i;
547
548 BUG_ON(!mutex_is_locked(&lguest_lock));
549
550 down_read(&lg->mm->mmap_sem);
551 for (i = 0; i < LGUEST_MAX_DMA; i++) {
552 if (lg->dma[i].interrupt)
553 unlink_dma(&lg->dma[i]);
554 }
555 up_read(&lg->mm->mmap_sem);
556}
557
558/*M:007 We only return a single DMA buffer to the Launcher, but it would be
559 * more efficient to return a pointer to the entire array of DMA buffers, which
560 * it can cache and choose one whenever it wants.
561 *
562 * Currently the Launcher uses a write to /dev/lguest, and the return value is
563 * the address of the DMA structure with the interrupt number placed in
564 * dma->used_len. If we wanted to return the entire array, we need to return
565 * the address, array size and interrupt number: this seems to require an
566 * ioctl(). :*/
567
568/*L:320 This routine looks for a DMA buffer registered by the Guest on the
569 * given key (using the BIND_DMA hypercall). */
570unsigned long get_dma_buffer(struct lguest *lg,
571 unsigned long ukey, unsigned long *interrupt)
572{
573 unsigned long ret = 0;
574 union futex_key key;
575 struct lguest_dma_info *i;
576 struct rw_semaphore *fshared = &current->mm->mmap_sem;
577
578 /* Take the Big Lguest Lock to stop other Guests sending this Guest DMA
579 * at the same time. */
580 mutex_lock(&lguest_lock);
581 /* To match between Guests sharing the same underlying memory we steal
582 * code from the futex infrastructure. This requires that we hold the
583 * "mmap_sem" for our process (the Launcher), and pass it to the futex
584 * code. */
585 down_read(fshared);
586
587 /* This can fail if it's not a valid address, or if the address is not
588 * divisible by 4 (the futex code needs that, we don't really). */
589 if (get_futex_key(lg->mem_base + ukey, fshared, &key) != 0) {
590 kill_guest(lg, "bad registered DMA buffer");
591 goto unlock;
592 }
593 /* Search the hash table for matching entries (the Launcher can only
594 * send to its own Guest for the moment, so the entry must be for this
595 * Guest) */
596 list_for_each_entry(i, &dma_hash[hash(&key)], list) {
597 if (key_eq(&key, &i->key) && i->owner == lg) {
598 unsigned int j;
599 /* Look through the registered DMA array for an
600 * available buffer. */
601 for (j = 0; j < i->num_dmas; j++) {
602 struct lguest_dma dma;
603
604 ret = i->dmas + j * sizeof(struct lguest_dma);
605 lgread(lg, &dma, ret, sizeof(dma));
606 if (dma.used_len == 0)
607 break;
608 }
609 /* Store the interrupt the Guest wants when the buffer
610 * is used. */
611 *interrupt = i->interrupt;
612 break;
613 }
614 }
615unlock:
616 up_read(fshared);
617 mutex_unlock(&lguest_lock);
618 return ret;
619}
620/*:*/
621
622/*L:410 This really has completed the Launcher. Not only have we now finished
623 * the longest chapter in our journey, but this also means we are over halfway
624 * through!
625 *
626 * Enough prevaricating around the bush: it is time for us to dive into the
627 * core of the Host, in "make Host".
628 */
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index e4845d7f068..4d45b7036e8 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -5,7 +5,6 @@
5#include <linux/types.h> 5#include <linux/types.h>
6#include <linux/init.h> 6#include <linux/init.h>
7#include <linux/stringify.h> 7#include <linux/stringify.h>
8#include <linux/futex.h>
9#include <linux/lguest.h> 8#include <linux/lguest.h>
10#include <linux/lguest_launcher.h> 9#include <linux/lguest_launcher.h>
11#include <linux/wait.h> 10#include <linux/wait.h>
@@ -17,17 +16,6 @@
17void free_pagetables(void); 16void free_pagetables(void);
18int init_pagetables(struct page **switcher_page, unsigned int pages); 17int init_pagetables(struct page **switcher_page, unsigned int pages);
19 18
20struct lguest_dma_info
21{
22 struct list_head list;
23 union futex_key key;
24 unsigned long dmas;
25 struct lguest *owner;
26 u16 next_dma;
27 u16 num_dmas;
28 u8 interrupt; /* 0 when not registered */
29};
30
31struct pgdir 19struct pgdir
32{ 20{
33 unsigned long gpgdir; 21 unsigned long gpgdir;
@@ -90,15 +78,11 @@ struct lguest
90 struct task_struct *wake; 78 struct task_struct *wake;
91 79
92 unsigned long noirq_start, noirq_end; 80 unsigned long noirq_start, noirq_end;
93 int dma_is_pending; 81 unsigned long pending_notify; /* pfn from LHCALL_NOTIFY */
94 unsigned long pending_dma; /* struct lguest_dma */
95 unsigned long pending_key; /* address they're sending to */
96 82
97 unsigned int stack_pages; 83 unsigned int stack_pages;
98 u32 tsc_khz; 84 u32 tsc_khz;
99 85
100 struct lguest_dma_info dma[LGUEST_MAX_DMA];
101
102 /* Dead? */ 86 /* Dead? */
103 const char *dead; 87 const char *dead;
104 88
@@ -184,15 +168,6 @@ extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
184int lguest_device_init(void); 168int lguest_device_init(void);
185void lguest_device_remove(void); 169void lguest_device_remove(void);
186 170
187/* io.c: */
188void lguest_io_init(void);
189int bind_dma(struct lguest *lg,
190 unsigned long key, unsigned long udma, u16 numdmas, u8 interrupt);
191void send_dma(struct lguest *info, unsigned long key, unsigned long udma);
192void release_all_dma(struct lguest *lg);
193unsigned long get_dma_buffer(struct lguest *lg, unsigned long key,
194 unsigned long *interrupt);
195
196/* hypercalls.c: */ 171/* hypercalls.c: */
197void do_hypercalls(struct lguest *lg); 172void do_hypercalls(struct lguest *lg);
198void write_timestamp(struct lguest *lg); 173void write_timestamp(struct lguest *lg);
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 61b177e1e64..ee405b38383 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -2,37 +2,12 @@
2 * controls and communicates with the Guest. For example, the first write will 2 * controls and communicates with the Guest. For example, the first write will
3 * tell us the Guest's memory layout, pagetable, entry point and kernel address 3 * tell us the Guest's memory layout, pagetable, entry point and kernel address
4 * offset. A read will run the Guest until something happens, such as a signal 4 * offset. A read will run the Guest until something happens, such as a signal
5 * or the Guest doing a DMA out to the Launcher. Writes are also used to get a 5 * or the Guest doing a NOTIFY out to the Launcher. :*/
6 * DMA buffer registered by the Guest and to send the Guest an interrupt. :*/
7#include <linux/uaccess.h> 6#include <linux/uaccess.h>
8#include <linux/miscdevice.h> 7#include <linux/miscdevice.h>
9#include <linux/fs.h> 8#include <linux/fs.h>
10#include "lg.h" 9#include "lg.h"
11 10
12/*L:310 To send DMA into the Guest, the Launcher needs to be able to ask for a
13 * DMA buffer. This is done by writing LHREQ_GETDMA and the key to
14 * /dev/lguest. */
15static long user_get_dma(struct lguest *lg, const unsigned long __user *input)
16{
17 unsigned long key, udma, irq;
18
19 /* Fetch the key they wrote to us. */
20 if (get_user(key, input) != 0)
21 return -EFAULT;
22 /* Look for a free Guest DMA buffer bound to that key. */
23 udma = get_dma_buffer(lg, key, &irq);
24 if (!udma)
25 return -ENOENT;
26
27 /* We need to tell the Launcher what interrupt the Guest expects after
28 * the buffer is filled. We stash it in udma->used_len. */
29 lgwrite_u32(lg, udma + offsetof(struct lguest_dma, used_len), irq);
30
31 /* The (guest-physical) address of the DMA buffer is returned from
32 * the write(). */
33 return udma;
34}
35
36/*L:315 To force the Guest to stop running and return to the Launcher, the 11/*L:315 To force the Guest to stop running and return to the Launcher, the
37 * Waker sets writes LHREQ_BREAK and the value "1" to /dev/lguest. The 12 * Waker sets writes LHREQ_BREAK and the value "1" to /dev/lguest. The
38 * Launcher then writes LHREQ_BREAK and "0" to release the Waker. */ 13 * Launcher then writes LHREQ_BREAK and "0" to release the Waker. */
@@ -102,10 +77,10 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
102 return len; 77 return len;
103 } 78 }
104 79
105 /* If we returned from read() last time because the Guest sent DMA, 80 /* If we returned from read() last time because the Guest notified,
106 * clear the flag. */ 81 * clear the flag. */
107 if (lg->dma_is_pending) 82 if (lg->pending_notify)
108 lg->dma_is_pending = 0; 83 lg->pending_notify = 0;
109 84
110 /* Run the Guest until something interesting happens. */ 85 /* Run the Guest until something interesting happens. */
111 return run_guest(lg, (unsigned long __user *)user); 86 return run_guest(lg, (unsigned long __user *)user);
@@ -216,7 +191,7 @@ unlock:
216/*L:010 The first operation the Launcher does must be a write. All writes 191/*L:010 The first operation the Launcher does must be a write. All writes
217 * start with a 32 bit number: for the first write this must be 192 * start with a 32 bit number: for the first write this must be
218 * LHREQ_INITIALIZE to set up the Guest. After that the Launcher can use 193 * LHREQ_INITIALIZE to set up the Guest. After that the Launcher can use
219 * writes of other values to get DMA buffers and send interrupts. */ 194 * writes of other values to send interrupts. */
220static ssize_t write(struct file *file, const char __user *in, 195static ssize_t write(struct file *file, const char __user *in,
221 size_t size, loff_t *off) 196 size_t size, loff_t *off)
222{ 197{
@@ -245,8 +220,6 @@ static ssize_t write(struct file *file, const char __user *in,
245 switch (req) { 220 switch (req) {
246 case LHREQ_INITIALIZE: 221 case LHREQ_INITIALIZE:
247 return initialize(file, input); 222 return initialize(file, input);
248 case LHREQ_GETDMA:
249 return user_get_dma(lg, input);
250 case LHREQ_IRQ: 223 case LHREQ_IRQ:
251 return user_send_irq(lg, input); 224 return user_send_irq(lg, input);
252 case LHREQ_BREAK: 225 case LHREQ_BREAK:
@@ -276,8 +249,6 @@ static int close(struct inode *inode, struct file *file)
276 mutex_lock(&lguest_lock); 249 mutex_lock(&lguest_lock);
277 /* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */ 250 /* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */
278 hrtimer_cancel(&lg->hrt); 251 hrtimer_cancel(&lg->hrt);
279 /* Free any DMA buffers the Guest had bound. */
280 release_all_dma(lg);
281 /* Free up the shadow page tables for the Guest. */ 252 /* Free up the shadow page tables for the Guest. */
282 free_guest_pagetable(lg); 253 free_guest_pagetable(lg);
283 /* Now all the memory cleanups are done, it's safe to release the 254 /* Now all the memory cleanups are done, it's safe to release the