[IA64] cpu hotplug: return offlined cpus to SAL

This patch is required to support cpu removal for IPF systems. Existing code
just fakes the real offline by keeping it run the idle thread, and polling
for the bit to re-appear in the cpu_state to get out of the idle loop.

For the cpu-offline to work correctly, we need to pass control of this CPU 
back to SAL so it can continue in the boot-rendez mode. This gives the
SAL control to not pick this cpu as the monarch processor for global MCA
events, and addition does not wait for this cpu to checkin with SAL
for global MCA events as well. The handoff is implemented as documented in 
SAL specification section 3.2.5.1 "OS_BOOT_RENDEZ to SAL return State"

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/include/asm-ia64/sal.h b/include/asm-ia64/sal.h
index ea1ed377de4c..240676f75390 100644
--- a/include/asm-ia64/sal.h
+++ b/include/asm-ia64/sal.h
@@ -832,6 +832,44 @@ extern int ia64_sal_oemcall_nolock(struct ia64_sal_retval *, u64, u64, u64,
 				   u64, u64, u64, u64, u64);
 extern int ia64_sal_oemcall_reentrant(struct ia64_sal_retval *, u64, u64, u64,
 				      u64, u64, u64, u64, u64);
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * System Abstraction Layer Specification
+ * Section 3.2.5.1: OS_BOOT_RENDEZ to SAL return State.
+ * Note: region regs are stored first in head.S _start. Hence they must
+ * stay up front.
+ */
+struct sal_to_os_boot {
+	u64 rr[8];		/* Region Registers */
+	u64	br[6];		/* br0: return addr into SAL boot rendez routine */
+	u64 gr1;		/* SAL:GP */
+	u64 gr12;		/* SAL:SP */
+	u64 gr13;		/* SAL: Task Pointer */
+	u64 fpsr;
+	u64	pfs;
+	u64 rnat;
+	u64 unat;
+	u64 bspstore;
+	u64 dcr;		/* Default Control Register */
+	u64 iva;
+	u64 pta;
+	u64 itv;
+	u64 pmv;
+	u64 cmcv;
+	u64 lrr[2];
+	u64 gr[4];
+	u64 pr;			/* Predicate registers */
+	u64 lc;			/* Loop Count */
+	struct ia64_fpreg fp[20];
+};
+
+/*
+ * Global array allocated for NR_CPUS at boot time
+ */
+extern struct sal_to_os_boot sal_boot_rendez_state[NR_CPUS];
+
+extern void ia64_jump_to_sal(struct sal_to_os_boot *);
+#endif
 
 extern void ia64_sal_handler_init(void *entry_point, void *gpval);