lguest: write more information to userspace about pending traps.

This is preparation for userspace handling MMIO and ioport accesses.

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

6 files changed, 42 insertions, 18 deletions

diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index cdb2f9aa5860..9159dbc583f6 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -229,16 +229,17 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
                  * It's possible the Guest did a NOTIFY hypercall to the
                  * Launcher.
                  */
-                if (cpu->pending_notify) {
+                if (cpu->pending.trap) {
                         /*
                          * Does it just needs to write to a registered
                          * eventfd (ie. the appropriate virtqueue thread)?
                          */
                         if (!send_notify_to_eventfd(cpu)) {
                                 /* OK, we tell the main Launcher. */
-                                if (put_user(cpu->pending_notify, user))
+                                if (copy_to_user(user, &cpu->pending,
+                                                 sizeof(cpu->pending)))
                                         return -EFAULT;
-                                return sizeof(cpu->pending_notify);
+                                return sizeof(cpu->pending);
                         }
                 }
 
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
index 83511eb0923d..5dd1fb8a6610 100644
--- a/drivers/lguest/hypercalls.c
+++ b/drivers/lguest/hypercalls.c
@@ -118,7 +118,8 @@ static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
                 cpu->halted = 1;
                 break;
         case LHCALL_NOTIFY:
-                cpu->pending_notify = args->arg1;
+                cpu->pending.trap = LGUEST_TRAP_ENTRY;
+                cpu->pending.addr = args->arg1;
                 break;
         default:
                 /* It should be an architecture-specific hypercall. */
@@ -189,7 +190,7 @@ static void do_async_hcalls(struct lg_cpu *cpu)
                  * Stop doing hypercalls if they want to notify the Launcher:
                  * it needs to service this first.
                  */
-                if (cpu->pending_notify)
+                if (cpu->pending.trap)
                         break;
         }
 }
@@ -280,7 +281,7 @@ void do_hypercalls(struct lg_cpu *cpu)
          * NOTIFY to the Launcher, we want to return now.  Otherwise we do
          * the hypercall.
          */
-        if (!cpu->pending_notify) {
+        if (!cpu->pending.trap) {
                 do_hcall(cpu, cpu->hcall);
                 /*
                  * Tricky point: we reset the hcall pointer to mark the
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index 1c98bf74fd68..020fec5bb072 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -50,7 +50,8 @@ struct lg_cpu {
         /* Bitmap of what has changed: see CHANGED_* above. */
         int changed;
 
-        unsigned long pending_notify; /* pfn from LHCALL_NOTIFY */
+        /* Pending operation. */
+        struct lguest_pending pending;
 
         unsigned long *reg_read; /* register from LHREQ_GETREG */
 
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 7f14c152dd23..dcf9efd94cf4 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -29,6 +29,10 @@ bool send_notify_to_eventfd(struct lg_cpu *cpu)
         unsigned int i;
         struct lg_eventfd_map *map;
 
+        /* We only connect LHCALL_NOTIFY to event fds, not other traps. */
+        if (cpu->pending.trap != LGUEST_TRAP_ENTRY)
+                return false;
+
         /*
          * This "rcu_read_lock()" helps track when someone is still looking at
          * the (RCU-using) eventfds array.  It's not actually a lock at all;
@@ -52,9 +56,9 @@ bool send_notify_to_eventfd(struct lg_cpu *cpu)
          * we'll continue to use the old array and just won't see the new one.
          */
         for (i = 0; i < map->num; i++) {
-                if (map->map[i].addr == cpu->pending_notify) {
+                if (map->map[i].addr == cpu->pending.addr) {
                         eventfd_signal(map->map[i].event, 1);
-                        cpu->pending_notify = 0;
+                        cpu->pending.trap = 0;
                         break;
                 }
         }
@@ -62,7 +66,7 @@ bool send_notify_to_eventfd(struct lg_cpu *cpu)
         rcu_read_unlock();
 
         /* If we cleared the notification, it's because we found a match. */
-        return cpu->pending_notify == 0;
+        return cpu->pending.trap == 0;
 }
 
 /*L:055
@@ -282,8 +286,8 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
          * If we returned from read() last time because the Guest sent I/O,
          * clear the flag.
          */
-        if (cpu->pending_notify)
-                cpu->pending_notify = 0;
+        if (cpu->pending.trap)
+                cpu->pending.trap = 0;
 
         /* Run the Guest until something interesting happens. */
         return run_guest(cpu, (unsigned long __user *)user);
diff --git a/include/linux/lguest_launcher.h b/include/linux/lguest_launcher.h
index f27cae27b0c1..c4451ebece47 100644
--- a/include/linux/lguest_launcher.h
+++ b/include/linux/lguest_launcher.h
@@ -68,6 +68,19 @@ enum lguest_req
 };
 
 /*
+ * This is what read() of the lguest fd populates.  trap ==
+ * LGUEST_TRAP_ENTRY for an LHCALL_NOTIFY (addr is the
+ * argument), 14 for a page fault in the MMIO region (addr is
+ * the trap address, insn is the instruction), or 13 for a GPF
+ * (insn is the instruction).
+ */
+struct lguest_pending {
+        __u8 trap;
+        __u8 insn[7];
+        __u32 addr;
+};
+
+/*
  * The alignment to use between consumer and producer parts of vring.
  * x86 pagesize for historical reasons.
  */
diff --git a/tools/lguest/lguest.c b/tools/lguest/lguest.c
index 3f7f2326cd9a..0e754d04876d 100644
--- a/tools/lguest/lguest.c
+++ b/tools/lguest/lguest.c
@@ -1820,17 +1820,21 @@ static void __attribute__((noreturn)) restart_guest(void)
 static void __attribute__((noreturn)) run_guest(void)
 {
         for (;;) {
-                unsigned long notify_addr;
+                struct lguest_pending notify;
                 int readval;
 
                 /* We read from the /dev/lguest device to run the Guest. */
-                readval = pread(lguest_fd, &notify_addr,
-                                sizeof(notify_addr), cpu_id);
+                readval = pread(lguest_fd, &notify, sizeof(notify), cpu_id);
 
                 /* One unsigned long means the Guest did HCALL_NOTIFY */
-                if (readval == sizeof(notify_addr)) {
-                        verbose("Notify on address %#lx\n", notify_addr);
-                        handle_output(notify_addr);
+                if (readval == sizeof(notify)) {
+                        if (notify.trap == 0x1F) {
+                                verbose("Notify on address %#08x\n",
+                                        notify.addr);
+                                handle_output(notify.addr);
+                        } else
+                                errx(1, "Unknown trap %i addr %#08x\n",
+                                     notify.trap, notify.addr);
                 /* ENOENT means the Guest died.  Reading tells us why. */
                 } else if (errno == ENOENT) {
                         char reason[1024] = { 0 };