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>

drivers/lguest/Makefile

@@ -1,7 +1,7 @@
 # Host requires the other files, which can be a module.
 obj-$(CONFIG_LGUEST)	+= lg.o
 lg-y = core.o hypercalls.o page_tables.o interrupts_and_traps.o \
-	segments.o io.o lguest_user.o
+	segments.o lguest_user.o
 
 lg-$(CONFIG_X86_32) += x86/switcher_32.o x86/core.o
 

drivers/lguest/core.c

@@ -202,13 +202,12 @@ int run_guest(struct lguest *lg, unsigned long __user *user)
 		if (lg->hcall)
 			do_hypercalls(lg);
 
-		/* It's possible the Guest did a SEND_DMA hypercall to the
+		/* It's possible the Guest did a NOTIFY hypercall to the
 		 * Launcher, in which case we return from the read() now. */
-		if (lg->dma_is_pending) {
-			if (put_user(lg->pending_dma, user) ||
-			    put_user(lg->pending_key, user+1))
+		if (lg->pending_notify) {
+			if (put_user(lg->pending_notify, user))
 				return -EFAULT;
-			return sizeof(unsigned long)*2;
+			return sizeof(lg->pending_notify);
 		}
 
 		/* Check for signals */
@@ -288,9 +287,6 @@ static int __init init(void)
 	if (err)
 		goto unmap;
 
-	/* The I/O subsystem needs some things initialized. */
-	lguest_io_init();
-
 	/* We might need to reserve an interrupt vector. */
 	err = init_interrupts();
 	if (err)

drivers/lguest/hypercalls.c

@@ -60,22 +60,9 @@ static void do_hcall(struct lguest *lg, struct hcall_args *args)
 		else
 			guest_pagetable_flush_user(lg);
 		break;
-	case LHCALL_BIND_DMA:
-		/* BIND_DMA really wants four arguments, but it's the only call
-		 * which does.  So the Guest packs the number of buffers and
-		 * the interrupt number into the final argument, and we decode
-		 * it here.  This can legitimately fail, since we currently
-		 * place a limit on the number of DMA pools a Guest can have.
-		 * So we return true or false from this call. */
-		args->arg0 = bind_dma(lg, args->arg1, args->arg2,
-				     args->arg3 >> 8, args->arg3 & 0xFF);
-		break;
 
 	/* All these calls simply pass the arguments through to the right
 	 * routines. */
-	case LHCALL_SEND_DMA:
-		send_dma(lg, args->arg1, args->arg2);
-		break;
 	case LHCALL_NEW_PGTABLE:
 		guest_new_pagetable(lg, args->arg1);
 		break;
@@ -99,6 +86,9 @@ static void do_hcall(struct lguest *lg, struct hcall_args *args)
 		/* Similarly, this sets the halted flag for run_guest(). */
 		lg->halted = 1;
 		break;
+	case LHCALL_NOTIFY:
+		lg->pending_notify = args->arg1;
+		break;
 	default:
 		if (lguest_arch_do_hcall(lg, args))
 			kill_guest(lg, "Bad hypercall %li\n", args->arg0);
@@ -156,9 +146,9 @@ static void do_async_hcalls(struct lguest *lg)
 			break;
 		}
 
- 		/* Stop doing hypercalls if we've just done a DMA to the
-		 * Launcher: it needs to service this first. */
-		if (lg->dma_is_pending)
+		/* Stop doing hypercalls if they want to notify the Launcher:
+		 * it needs to service this first. */
+		if (lg->pending_notify)
 			break;
 	}
 }
@@ -220,9 +210,9 @@ void do_hypercalls(struct lguest *lg)
 	do_async_hcalls(lg);
 
 	/* If we stopped reading the hypercall ring because the Guest did a
-	 * SEND_DMA to the Launcher, we want to return now.  Otherwise we do
+	 * NOTIFY to the Launcher, we want to return now.  Otherwise we do
 	 * the hypercall. */
-	if (!lg->dma_is_pending) {
+	if (!lg->pending_notify) {
 		do_hcall(lg, lg->hcall);
 		/* Tricky point: we reset the hcall pointer to mark the
 		 * hypercall as "done".  We use the hcall pointer rather than