[SPARC64]: Initial LDOM cpu hotplug support.

Only adding cpus is supports at the moment, removal
will come next.

When new cpus are configured, the machine description is
updated.  When we get the configure request we pass in a
cpu mask of to-be-added cpus to the mdesc CPU node parser
so it only fetches information for those cpus.  That code
also proceeds to update the SMT/multi-core scheduling bitmaps.

cpu_up() does all the work and we return the status back
over the DS channel.

CPUs via dr-cpu need to be booted straight out of the
hypervisor, and this requires:

1) A new trampoline mechanism.  CPUs are booted straight
   out of the hypervisor with MMU disabled and running in
   physical addresses with no mappings installed in the TLB.

   The new hvtramp.S code sets up the critical cpu state,
   installs the locked TLB mappings for the kernel, and
   turns the MMU on.  It then proceeds to follow the logic
   of the existing trampoline.S SMP cpu bringup code.

2) All calls into OBP have to be disallowed when domaining
   is enabled.  Since cpus boot straight into the kernel from
   the hypervisor, OBP has no state about that cpu and therefore
   cannot handle being invoked on that cpu.

   Luckily it's only a handful of interfaces which can be called
   after the OBP device tree is obtained.  For example, rebooting,
   halting, powering-off, and setting options node variables.

CPU removal support will require some infrastructure changes
here.  Namely we'll have to process the requests via a true
kernel thread instead of in a workqueue.  workqueues run on
a per-cpu thread, but when unconfiguring we might need to
force the thread to execute on another cpu if the current cpu
is the one being removed.  Removal of a cpu also causes the kernel
to destroy that cpu's workqueue running thread.

Another issue on removal is that we may have interrupts still
pointing to the cpu-to-be-removed.  So new code will be needed
to walk the active INO list and retarget those cpus as-needed.

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

6 files changed, 50 insertions, 5 deletions

diff --git a/include/asm-sparc64/cpudata.h b/include/asm-sparc64/cpudata.h
index 445026fbec35..0016d8b4531c 100644
--- a/include/asm-sparc64/cpudata.h
+++ b/include/asm-sparc64/cpudata.h
@@ -80,7 +80,8 @@ struct trap_per_cpu {
         unsigned int            dev_mondo_qmask;
         unsigned int            resum_qmask;
         unsigned int            nonresum_qmask;
-        unsigned int            __pad2[3];
+        unsigned int            __pad2[1];
+        void                    *hdesc;
 } __attribute__((aligned(64)));
 extern struct trap_per_cpu trap_block[NR_CPUS];
 extern void init_cur_cpu_trap(struct thread_info *);
diff --git a/include/asm-sparc64/hvtramp.h b/include/asm-sparc64/hvtramp.h
new file mode 100644
index 000000000000..c7dd6ad056df
--- /dev/null
+++ b/include/asm-sparc64/hvtramp.h
@@ -0,0 +1,37 @@
+#ifndef _SPARC64_HVTRAP_H
+#define _SPARC64_HVTRAP_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+
+struct hvtramp_mapping {
+        __u64           vaddr;
+        __u64           tte;
+};
+
+struct hvtramp_descr {
+        __u32                   cpu;
+        __u32                   num_mappings;
+        __u64                   fault_info_va;
+        __u64                   fault_info_pa;
+        __u64                   thread_reg;
+        struct hvtramp_mapping  maps[2];
+};
+
+extern void hv_cpu_startup(unsigned long hvdescr_pa);
+
+#endif
+
+#define HVTRAMP_DESCR_CPU               0x00
+#define HVTRAMP_DESCR_NUM_MAPPINGS      0x04
+#define HVTRAMP_DESCR_FAULT_INFO_VA     0x08
+#define HVTRAMP_DESCR_FAULT_INFO_PA     0x10
+#define HVTRAMP_DESCR_THREAD_REG        0x18
+#define HVTRAMP_DESCR_MAPS              0x20
+
+#define HVTRAMP_MAPPING_VADDR           0x00
+#define HVTRAMP_MAPPING_TTE             0x08
+#define HVTRAMP_MAPPING_SIZE            0x10
+
+#endif /* _SPARC64_HVTRAP_H */
diff --git a/include/asm-sparc64/hypervisor.h b/include/asm-sparc64/hypervisor.h
index db2130a95d68..524d49835dfd 100644
--- a/include/asm-sparc64/hypervisor.h
+++ b/include/asm-sparc64/hypervisor.h
@@ -98,7 +98,7 @@
 #define HV_FAST_MACH_EXIT               0x00
 
 #ifndef __ASSEMBLY__
-extern void sun4v_mach_exit(unsigned long exit_core);
+extern void sun4v_mach_exit(unsigned long exit_code);
 #endif
 
 /* Domain services.  */
diff --git a/include/asm-sparc64/ldc.h b/include/asm-sparc64/ldc.h
index a21996c6b155..8d17bd6bd5db 100644
--- a/include/asm-sparc64/ldc.h
+++ b/include/asm-sparc64/ldc.h
@@ -6,6 +6,8 @@
 extern int ldom_domaining_enabled;
 extern void ldom_set_var(const char *var, const char *value);
 extern void ldom_reboot(const char *boot_command);
+extern void ldom_power_off(void);
+extern void ldom_startcpu_cpuid(unsigned int cpu, unsigned long thread_reg);
 
 /* The event handler will be evoked when link state changes
  * or data becomes available on the receive side.
diff --git a/include/asm-sparc64/mdesc.h b/include/asm-sparc64/mdesc.h
index dc372df23fb3..e97c43133752 100644
--- a/include/asm-sparc64/mdesc.h
+++ b/include/asm-sparc64/mdesc.h
@@ -2,6 +2,7 @@
 #define _SPARC64_MDESC_H
 
 #include <linux/types.h>
+#include <linux/cpumask.h>
 #include <asm/prom.h>
 
 struct mdesc_handle;
@@ -60,6 +61,8 @@ extern u64 mdesc_arc_target(struct mdesc_handle *hp, u64 arc);
 
 extern void mdesc_update(void);
 
+extern void mdesc_fill_in_cpu_data(cpumask_t mask);
+
 extern void sun4v_mdesc_init(void);
 
 #endif
diff --git a/include/asm-sparc64/smp.h b/include/asm-sparc64/smp.h
index 4fb8c4bfb848..c42c5a035c73 100644
--- a/include/asm-sparc64/smp.h
+++ b/include/asm-sparc64/smp.h
@@ -29,9 +29,6 @@
 #include <asm/bitops.h>
 #include <asm/atomic.h>
 
-extern cpumask_t phys_cpu_present_map;
-#define cpu_possible_map phys_cpu_present_map
-
 extern cpumask_t cpu_sibling_map[NR_CPUS];
 extern cpumask_t cpu_core_map[NR_CPUS];
 extern int sparc64_multi_core;
@@ -46,6 +43,11 @@ extern int hard_smp_processor_id(void);
 extern void smp_fill_in_sib_core_maps(void);
 extern unsigned char boot_cpu_id;
 
+#ifdef CONFIG_HOTPLUG_CPU
+extern int __cpu_disable(void);
+extern void __cpu_die(unsigned int cpu);
+#endif
+
 #endif /* !(__ASSEMBLY__) */
 
 #else