powerpc: Fix definition of SIAR and SDAR registers

BugLink: http://bugs.launchpad.net/bugs/1596575
commit d23fac2b27d94aeb7b65536a50d32bfdc21fe01e upstream.

The SIAR and SDAR registers are available twice, one time as SPRs
780 / 781 (unprivileged, but read-only), and one time as the SPRs
796 / 797 (privileged, but read and write). The Linux kernel code
currently uses the unprivileged  SPRs - while this is OK for reading,
writing to that register of course does not work.
Since the KVM code tries to write to this register, too (see the mtspr
in book3s_hv_rmhandlers.S), the contents of this register sometimes get
lost for the guests, e.g. during migration of a VM.
To fix this issue, simply switch to the privileged SPR numbers instead.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 9b92693e4c46317287c2d0be44251dea7a9eeab0..5d3c539edbfe3bb6ddc73589b3fbf030e6528528 100644 (file)
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -744,13 +744,13 @@
 #define SPRN_PMC6      792
 #define SPRN_PMC7      793
 #define SPRN_PMC8      794
-#define SPRN_SIAR      780
-#define SPRN_SDAR      781
 #define SPRN_SIER      784
 #define   SIER_SIPR            0x2000000       /* Sampled MSR_PR */
 #define   SIER_SIHV            0x1000000       /* Sampled MSR_HV */
 #define   SIER_SIAR_VALID      0x0400000       /* SIAR contents valid */
 #define   SIER_SDAR_VALID      0x0200000       /* SDAR contents valid */
+#define SPRN_SIAR      796
+#define SPRN_SDAR      797
 #define SPRN_TACR      888
 #define SPRN_TCSCR     889
 #define SPRN_CSIGR     890