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s390/kdump: fix nosmt kernel parameter

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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 <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Michael Holzheu
2015-05-26 19:05:23 +02:00
committed by Martin Schwidefsky
parent 1d1858d244
commit 1592a8e456
7 changed files with 64 additions and 61 deletions
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25
arch/s390/kernel/crash_dump.c
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@@ -44,31 +44,6 @@ static struct memblock_type oldmem_type = {
struct dump_save_areas dump_save_areas;
/*
* Allocate and add a save area for a CPU
*/
struct save_area_ext *dump_save_area_create(int cpu)
{
struct save_area_ext **save_areas, *save_area;
save_area = kmalloc(sizeof(*save_area), GFP_KERNEL);
if (!save_area)
return NULL;
if (cpu + 1 > dump_save_areas.count) {
dump_save_areas.count = cpu + 1;
save_areas = krealloc(dump_save_areas.areas,
dump_save_areas.count * sizeof(void *),
GFP_KERNEL | __GFP_ZERO);
if (!save_areas) {
kfree(save_area);
return NULL;
}
dump_save_areas.areas = save_areas;
}
dump_save_areas.areas[cpu] = save_area;
return save_area;
}
/*
* Return physical address for virtual address
*/