[SPARC64]: Use sun4v VIRQ interfaces as intended.

We were simply concatenating the devhandle and devino and using that
as the cookie, which defeats the entire purpose of the VIRQ hypervisor
interfaces.

Now that we use physical addresses for the INO buckets, we can
allocate them dynamically for VIRQs and encode the cookies as
~__pa(bucket).  This allows us to test for and decode the cookie with
a simple:

	brlz	$reg1, 1f
	 xnor	$reg1, %g0, $reg2

sequence.

This works because bit 64 is never set in traditional
INO vectors, and it is also never set in a physical
address.  So xnor'ing the physical address of the bucket
always gives us a negative number, and thus a unique
condition we can test cheaply.

Inspired by ideas from Greg Onufer.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/arch/sparc64/kernel/sun4v_ivec.S b/arch/sparc64/kernel/sun4v_ivec.S
index 16d306445912..e2f8e1b4882a 100644
--- a/arch/sparc64/kernel/sun4v_ivec.S
+++ b/arch/sparc64/kernel/sun4v_ivec.S
@@ -98,13 +98,17 @@ sun4v_dev_mondo:
 
         TRAP_LOAD_IRQ_WORK_PA(%g1, %g4)
 
+        /* For VIRQs, cookie is encoded as ~bucket_phys_addr  */
+        brlz,pt %g3, 1f
+         xnor   %g3, %g0, %g4
+
         /* Get __pa(&ivector_table[IVEC]) into %g4.  */
         sethi   %hi(ivector_table_pa), %g4
         ldx     [%g4 + %lo(ivector_table_pa)], %g4
         sllx    %g3, 4, %g3
         add     %g4, %g3, %g4
 
-        ldx     [%g1], %g2
+1:      ldx     [%g1], %g2
         stxa    %g2, [%g4] ASI_PHYS_USE_EC
         stx     %g4, [%g1]