x86/paravirt: split sysret and sysexit

Don't conflate sysret and sysexit; they're different instructions with
different semantics, and may be in use at the same time (at least
within the same kernel, depending on whether its an Intel or AMD
system).

sysexit - just return to userspace, does no register restoration of
    any kind; must explicitly atomically enable interrupts.

sysret - reloads flags from r11, so no need to explicitly enable
    interrupts on 64-bit, responsible for restoring usermode %gs

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citirx.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/x86/kernel/vmi_32.c b/arch/x86/kernel/vmi_32.c
index 956f38927aa7..946bf13b44ab 100644
--- a/arch/x86/kernel/vmi_32.c
+++ b/arch/x86/kernel/vmi_32.c
@@ -151,7 +151,7 @@ static unsigned vmi_patch(u8 type, u16 clobbers, void *insns,
                                               insns, ip);
                 case PARAVIRT_PATCH(pv_cpu_ops.iret):
                         return patch_internal(VMI_CALL_IRET, len, insns, ip);
-                case PARAVIRT_PATCH(pv_cpu_ops.irq_enable_syscall_ret):
+                case PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit):
                         return patch_internal(VMI_CALL_SYSEXIT, len, insns, ip);
                 default:
                         break;
@@ -896,7 +896,7 @@ static inline int __init activate_vmi(void)
          * the backend.  They are performance critical anyway, so requiring
          * a patch is not a big problem.
          */
-        pv_cpu_ops.irq_enable_syscall_ret = (void *)0xfeedbab0;
+        pv_cpu_ops.irq_enable_sysexit = (void *)0xfeedbab0;
         pv_cpu_ops.iret = (void *)0xbadbab0;
 
 #ifdef CONFIG_SMP