[SPARC64]: Fix bugs in SUN4V cpu mondo dispatch.

There were several bugs in the SUN4V cpu mondo dispatch code.

In fact, if we ever got a EWOULDBLOCK or other error from
the hypervisor call, we'd potentially send a cpu mondo multiple
times to the same cpu and even worse we could loop until the
timeout resending the same mondo over and over to such cpus.

So let's bulletproof this thing as follows:

1) Implement cpu_mondo_send() and cpu_state() hypervisor calls
   in arch/sparc64/kernel/entry.S, add prototypes to asm/hypervisor.h

2) Don't build and update the cpulist using inline functions, this
   was causing the cpu mask to not get updated in the caller.

3) Disable interrupts during the entire mondo send, otherwise our
   cpu list and/or mondo block could get overwritten if we take
   an interrupt and do a cpu mondo send on the current cpu.

4) Check for all possible error return types from the cpu_mondo_send()
   hypervisor call.  In particular:

   HV_EOK) Our work is done, all cpus have received the mondo.
   HV_CPUERROR) One or more of the cpus in the cpu list we passed
                to the hypervisor are in error state.  Use cpu_state()
                calls over the entries in the cpu list to see which
		ones.  Record them in "error_mask" and report this
		after we are done sending the mondo to cpus which are
		not in error state.
   HV_EWOULDBLOCK) We need to keep trying.

   Any other error we consider fatal, we report the event and exit
   immediately.

5) We only timeout if forward progress is not made.  Forward progress
   is defined as having at least one cpu get the mondo successfully
   in a given cpu_mondo_send() call.  Otherwise we bump a counter
   and delay a little.  If the counter hits a limit, we signal an
   error and report the event.

Also, smp_call_function_mask() error handling reports the number
of cpus incorrectly.

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

1 files changed, 10 insertions, 0 deletions

diff --git a/include/asm-sparc64/hypervisor.h b/include/asm-sparc64/hypervisor.h
index 726e2ea03ce3..612bf319753f 100644
--- a/include/asm-sparc64/hypervisor.h
+++ b/include/asm-sparc64/hypervisor.h
@@ -342,6 +342,8 @@ extern unsigned long sun4v_cpu_qconf(unsigned long type,
  *              ENOCPU          Invalid cpu in CPU list
  *              EWOULDBLOCK     Some or all of the listed CPUs did not receive
  *                              the mondo
+ *              ECPUERROR       One or more of the listed CPUs are in error
+ *                              state, use HV_FAST_CPU_STATE to see which ones
  *              EINVAL          CPU list includes caller's CPU ID
  *
  * Send a mondo interrupt to the CPUs in the given CPU list with the
@@ -355,6 +357,10 @@ extern unsigned long sun4v_cpu_qconf(unsigned long type,
  */
 #define HV_FAST_CPU_MONDO_SEND          0x42
 
+#ifndef __ASSEMBLY__
+extern unsigned long sun4v_cpu_mondo_send(unsigned long cpu_count, unsigned long cpu_list_pa, unsigned long mondo_block_pa);
+#endif
+
 /* cpu_myid()
  * TRAP:        HV_FAST_TRAP
  * FUNCTION:    HV_FAST_CPU_MYID
@@ -382,6 +388,10 @@ extern unsigned long sun4v_cpu_qconf(unsigned long type,
 #define  HV_CPU_STATE_RUNNING            0x02
 #define  HV_CPU_STATE_ERROR              0x03
 
+#ifndef __ASSEMBLY__
+extern long sun4v_cpu_state(unsigned long cpuid);
+#endif
+
 /* cpu_set_rtba()
  * TRAP:        HV_FAST_TRAP
  * FUNCTION:    HV_FAST_CPU_SET_RTBA