powerpc: Fix definition of SIAR and SDAR registers

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>

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 2220f7a60def314be5c8f23e18ceb8982061cb18..93d69bd260e75c17431cffd63905aa5ed1b9f7f6 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