lguest: suppress interrupts for single insn, not range.

The last patch reduced our interrupt-suppression region to one address,
so simplify the code somewhat.

Also, remove the obsolete undefined instruction ranges and the comment
which refers to lguest_guest.S instead of head_32.S.

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

3 files changed, 9 insertions, 16 deletions

diff --git a/arch/x86/include/asm/lguest.h b/arch/x86/include/asm/lguest.h
index e2d4a4afa8c3..3bbc07a57a31 100644
--- a/arch/x86/include/asm/lguest.h
+++ b/arch/x86/include/asm/lguest.h
@@ -20,13 +20,10 @@ extern unsigned long switcher_addr;
 /* Found in switcher.S */
 extern unsigned long default_idt_entries[];
 
-/* Declarations for definitions in lguest_guest.S */
-extern char lguest_noirq_start[], lguest_noirq_end[];
+/* Declarations for definitions in arch/x86/lguest/head_32.S */
+extern char lguest_noirq_iret[];
 extern const char lgstart_cli[], lgend_cli[];
-extern const char lgstart_sti[], lgend_sti[];
-extern const char lgstart_popf[], lgend_popf[];
 extern const char lgstart_pushf[], lgend_pushf[];
-extern const char lgstart_iret[], lgend_iret[];
 
 extern void lguest_iret(void);
 extern void lguest_init(void);
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 543510a2f9e0..13616d708389 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -87,8 +87,7 @@
 
 struct lguest_data lguest_data = {
 	.hcall_status = { [0 ... LHCALL_RING_SIZE-1] = 0xFF },
-	.noirq_start = (u32)lguest_noirq_start,
-	.noirq_end = (u32)lguest_noirq_end,
+	.noirq_iret = (u32)lguest_noirq_iret,
 	.kernel_address = PAGE_OFFSET,
 	.blocked_interrupts = { 1 }, /* Block timer interrupts */
 	.syscall_vec = SYSCALL_VECTOR,
diff --git a/arch/x86/lguest/head_32.S b/arch/x86/lguest/head_32.S
index 81678bf0fcb7..d5ae63f5ec5d 100644
--- a/arch/x86/lguest/head_32.S
+++ b/arch/x86/lguest/head_32.S
@@ -133,9 +133,8 @@ ENTRY(lg_restore_fl)
 	ret
 /*:*/
 
-/* These demark the EIP range where host should never deliver interrupts. */
-.global lguest_noirq_start
-.global lguest_noirq_end
+/* These demark the EIP where host should never deliver interrupts. */
+.global lguest_noirq_iret
 
 /*M:004
  * When the Host reflects a trap or injects an interrupt into the Guest, it
@@ -174,12 +173,11 @@ ENTRY(lg_restore_fl)
  *
  * The second is harder: copying eflags to lguest_data.irq_enabled will turn
  * interrupts on before we're finished, so we could be interrupted before we
- * return to userspace or wherever.  Our solution to this is to surround the
- * code with lguest_noirq_start: and lguest_noirq_end: labels.  We tell the
+ * return to userspace or wherever.  Our solution to this is to tell the
  * Host that it is *never* to interrupt us there, even if interrupts seem to be
  * enabled. (It's not necessary to protect pop instruction, since
- * data gets updated only after it completes, so we end up surrounding
- * just one instruction, iret).
+ * data gets updated only after it completes, so we only need to protect
+ * one instruction, iret).
  */
 ENTRY(lguest_iret)
 	pushl	2*4(%esp)
@@ -190,6 +188,5 @@ ENTRY(lguest_iret)
 	 * prefix makes sure we use the stack segment, which is still valid.
 	 */
 	popl	%ss:lguest_data+LGUEST_DATA_irq_enabled
-lguest_noirq_start:
+lguest_noirq_iret:
 	iret
-lguest_noirq_end: