lwn.git/arch/s390/include/asm/smp.h, branch v4.4.30

s390/kdump: fix compile for !SMP

2015-06-29T08:13:11+00:00

Fix this compile error: arch/s390/kernel/setup.c:875:2: error: implicit declaration of function 'smp_save_dump_cpus' Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/kdump: fix nosmt kernel parameter

2015-06-25T07:39:26+00:00

It turned out that SIGP set-multi-threading can only be done once. Therefore switching to a different MT level after switching to sclp.mtid_prev in the dump case fails. As a symptom specifying the "nosmt" parameter currently fails for the kdump kernel and the kernel starts with multi-threading enabled. So fix this and issue diag 308 subcode 1 call after collecting the CPU states for the dump. Also enhance the diag308_reset() function to be usable also with enabled lowcore protection and prefix register != 0. After the reset it is possible to switch the MT level again. We have to do the reset very early in order not to kill the already initialized console. Therefore instead of kmalloc() the corresponding memblock functions have to be used. To avoid copying the sclp cpu code into sclp_early, we now use the simple sigp loop method for CPU detection. Signed-off-by: Michael Holzheu Signed-off-by: Martin Schwidefsky

s390: add SMT support

2015-01-22T11:16:01+00:00

The multi-threading facility is introduced with the z13 processor family. This patch adds code to detect the multi-threading facility. With the facility enabled each core will surface multiple hardware threads to the system. Each hardware threads looks like a normal CPU to the operating system with all its registers and properties. The SCLP interface reports the SMT topology indirectly via the maximum thread id. Each reported CPU in the result of a read-scp-information is a core representing a number of hardware threads. To reflect the reduced CPU capacity if two hardware threads run on a single core the MT utilization counter set is used to normalize the raw cputime obtained by the CPU timer deltas. This scaled cputime is reported via the taskstats interface. The normal /proc/stat numbers are based on the raw cputime and are not affected by the normalization. Signed-off-by: Martin Schwidefsky

s390/rwlock: use directed yield for write-locked rwlocks

2014-09-25T08:52:05+00:00

Add an owner field to the arch_rwlock_t to be able to pass the timeslice of a virtual CPU with diagnose 0x9c to the lock owner in case the rwlock is write-locked. The undirected yield in case the rwlock is acquired writable but the lock is read-locked is removed. Signed-off-by: Martin Schwidefsky

s390/smp: Avoid busy loop after halt and "begin" on z/VM

2014-05-20T06:58:45+00:00

Currently the smp_stop_cpu() function for SMP kernels enters a busy loop when "begin" is entered on the z/VM console after Linux is halted. To avoid this behavior, use the non-SMP variant of smp_stop_cpu() which stops the CPU again after "begin" is entered. As a side effect we now have consistent behavior for SMP and non-SMP Linux. Signed-off-by: Michael Holzheu Signed-off-by: Martin Schwidefsky

s390/smp: fix smp_stop_cpu() for !CONFIG_SMP

2014-04-09T08:19:12+00:00

smp_stop_cpu() should stop the current cpu even for !CONFIG_SMP. Otherwise machine_halt() will return and and the machine generates a panic instread of simply stopping the current cpu: Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000 CPU: 0 PID: 1 Comm: systemd-shutdow Not tainted 3.14.0-01527-g2b6ef16a6bc5 #10 [...] Call Trace: ([<0000000000110db0>] show_trace+0xf8/0x158) [<0000000000110e7a>] show_stack+0x6a/0xe8 [<000000000074dba8>] panic+0xe4/0x268 [<0000000000140570>] do_exit+0xa88/0xb2c [<000000000016e12c>] SyS_reboot+0x1f0/0x234 [<000000000075da70>] sysc_nr_ok+0x22/0x28 [<000000007d5a09b4>] 0x7d5a09b4 Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/smp: improve setup of possible cpu mask

2013-12-18T16:35:18+00:00

Since under z/VM we cannot have more than 64 cpus, make sure the cpu_possible_mask does not contain more bits. This avoids wasting memory for dynamic per-cpu allocations if CONFIG_NR_CPUS is larger than 64. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390: Remove zfcpdump NR_CPUS dependency

2013-10-24T15:17:04+00:00

Currently zfpcdump can only collect registers for up to CONFIG_NR_CPUS CPUss. This dependency is not necessary. So remove it by dynamically allocating the save area array. Signed-off-by: Michael Holzheu Reviewed-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/smp,topology: add polarization member to pcpu struct

2012-09-26T13:45:09+00:00

The cpu polarization member is the only per cpu state that is not part of the pcpu structure. So add it there and have everything in one place. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/smp: fix smp_find_processor_id() argument mismatch

2012-09-26T13:44:53+00:00

For SMP and !SMP smp_find_processor_id() either takes a u16 or an unsigned int argument. Fix this so both versions take a u16. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky