Remove fixed limit on number of guests, and lguests array.

Back when we had all the Guest state in the switcher, we had a fixed
array of them.  This is no longer necessary.

If we switch the network code to using random_ether_addr (46 bits is
enough to avoid clashes), we can get rid of the concept of "guest id"
altogether.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

5 files changed, 13 insertions, 37 deletions

diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index eb95860cf098..ca581ef591e8 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -47,10 +47,6 @@ static struct {
 DEFINE_MUTEX(lguest_lock);
 static DEFINE_PER_CPU(struct lguest *, last_guest);
 
-/* FIXME: Make dynamic. */
-#define MAX_LGUEST_GUESTS 16
-struct lguest lguests[MAX_LGUEST_GUESTS];
-
 /* Offset from where switcher.S was compiled to where we've copied it */
 static unsigned long switcher_offset(void)
 {
@@ -660,16 +656,6 @@ int run_guest(struct lguest *lg, unsigned long __user *user)
  * deliver_trap() and demand_page().  After all those, we'll be ready to
  * examine the Switcher, and our philosophical understanding of the Host/Guest
  * duality will be complete. :*/
-
-int find_free_guest(void)
-{
-        unsigned int i;
-        for (i = 0; i < MAX_LGUEST_GUESTS; i++)
-                if (!lguests[i].tsk)
-                        return i;
-        return -1;
-}
-
 static void adjust_pge(void *on)
 {
         if (on)
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
index 02e67b49ea4f..8bde20934f91 100644
--- a/drivers/lguest/hypercalls.c
+++ b/drivers/lguest/hypercalls.c
@@ -225,9 +225,7 @@ static void initialize(struct lguest *lg)
             /* We tell the Guest that it can't use the top 4MB of virtual
              * addresses used by the Switcher. */
             || put_user(4U*1024*1024, &lg->lguest_data->reserve_mem)
-            || put_user(tsc_speed, &lg->lguest_data->tsc_khz)
-            /* We also give the Guest a unique id, as used in lguest_net.c. */
-            || put_user(lg->guestid, &lg->lguest_data->guestid))
+            || put_user(tsc_speed, &lg->lguest_data->tsc_khz))
                 kill_guest(lg, "bad guest page %p", lg->lguest_data);
 
         /* We write the current time into the Guest's data page once now. */
diff --git a/drivers/lguest/io.c b/drivers/lguest/io.c
index 3a845335fee8..0e842e9caf68 100644
--- a/drivers/lguest/io.c
+++ b/drivers/lguest/io.c
@@ -212,7 +212,7 @@ int bind_dma(struct lguest *lg,
                         lg->dma[i].num_dmas = numdmas;
                         lg->dma[i].next_dma = 0;
                         lg->dma[i].key = key;
-                        lg->dma[i].guestid = lg->guestid;
+                        lg->dma[i].owner = lg;
                         lg->dma[i].interrupt = interrupt;
 
                         /* Now we add it to the hash table: the position
@@ -412,7 +412,7 @@ static int dma_transfer(struct lguest *srclg,
 
         /* From the "struct lguest_dma_info" we found in the hash, grab the
          * Guest. */
-        dstlg = &lguests[dst->guestid];
+        dstlg = dst->owner;
         /* Read in the source "struct lguest_dma" handed to SEND_DMA. */
         lgread(srclg, &src_dma, udma, sizeof(src_dma));
 
@@ -506,8 +506,8 @@ again:
                 struct lguest_dma_info *i;
                 /* Look through the hash for other Guests. */
                 list_for_each_entry(i, &dma_hash[hash(&key)], list) {
-                        /* Don't send to ourselves. */
-                        if (i->guestid == lg->guestid)
+                        /* Don't send to ourselves (would deadlock). */
+                        if (i->owner->mm == lg->mm)
                                 continue;
                         if (!key_eq(&key, &i->key))
                                 continue;
@@ -594,7 +594,7 @@ unsigned long get_dma_buffer(struct lguest *lg,
          * send to its own Guest for the moment, so the entry must be for this
          * Guest) */
         list_for_each_entry(i, &dma_hash[hash(&key)], list) {
-                if (key_eq(&key, &i->key) && i->guestid == lg->guestid) {
+                if (key_eq(&key, &i->key) && i->owner == lg) {
                         unsigned int j;
                         /* Look through the registered DMA array for an
                          * available buffer. */
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index 54f2c2472bec..c9d1dc29490d 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -51,9 +51,9 @@ struct lguest_dma_info
         struct list_head list;
         union futex_key key;
         unsigned long dmas;
+        struct lguest *owner;
         u16 next_dma;
         u16 num_dmas;
-        u16 guestid;
         u8 interrupt;   /* 0 when not registered */
 };
 
@@ -140,7 +140,6 @@ struct lguest
         struct lguest_data __user *lguest_data;
         struct task_struct *tsk;
         struct mm_struct *mm;   /* == tsk->mm, but that becomes NULL on exit */
-        u16 guestid;
         u32 pfn_limit;
         /* This provides the offset to the base of guest-physical
          * memory in the Launcher. */
@@ -195,7 +194,6 @@ struct lguest
         DECLARE_BITMAP(irqs_pending, LGUEST_IRQS);
 };
 
-extern struct lguest lguests[];
 extern struct mutex lguest_lock;
 
 /* core.c: */
@@ -203,7 +201,6 @@ u32 lgread_u32(struct lguest *lg, unsigned long addr);
 void lgwrite_u32(struct lguest *lg, unsigned long addr, u32 val);
 void lgread(struct lguest *lg, void *buf, unsigned long addr, unsigned len);
 void lgwrite(struct lguest *lg, unsigned long, const void *buf, unsigned len);
-int find_free_guest(void);
 int lguest_address_ok(const struct lguest *lg,
                       unsigned long addr, unsigned long len);
 int run_guest(struct lguest *lg, unsigned long __user *user);
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 816d4d12a801..5632ed82798a 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -167,11 +167,11 @@ static int initialize(struct file *file, const u32 __user *input)
         /* "struct lguest" contains everything we (the Host) know about a
          * Guest. */
         struct lguest *lg;
-        int err, i;
+        int err;
         u32 args[5];
 
-        /* We grab the Big Lguest lock, which protects the global array
-         * "lguests" and multiple simultaneous initializations. */
+        /* We grab the Big Lguest lock, which protects against multiple
+         * simultaneous initializations. */
         mutex_lock(&lguest_lock);
         /* You can't initialize twice!  Close the device and start again... */
         if (file->private_data) {
@@ -184,18 +184,13 @@ static int initialize(struct file *file, const u32 __user *input)
                 goto unlock;
         }
 
-        /* Find an unused guest. */
-        i = find_free_guest();
-        if (i < 0) {
-                err = -ENOSPC;
+        lg = kzalloc(sizeof(*lg), GFP_KERNEL);
+        if (!lg) {
+                err = -ENOMEM;
                 goto unlock;
         }
-        /* OK, we have an index into the "lguest" array: "lg" is a convenient
-         * pointer. */
-        lg = &lguests[i];
 
         /* Populate the easy fields of our "struct lguest" */
-        lg->guestid = i;
         lg->mem_base = (void __user *)(long)args[0];
         lg->pfn_limit = args[1];
         lg->page_offset = args[4];