PAPR specifies that DTL buffers can not cross AMS environments (aka CMO
in the PAPR) and can not cross a memory entitlement granule boundary
(4k). This is found in section 14.11.3.2 H_REGISTER_VPA of the PAPR.
kmalloc does not guarantee an alignment of the allocation, though,
beyond 8 bytes (at least in my understanding). Over-allocate and align
the resulting address. Tested both with and without AMS on a p7
partition.
Signed-off-by: Nishanth Aravamudan <n...@us.ibm.com>
---
Note, I initially put this in a firmware check if-block, but we have
also seen some issues with alignment with non-AMS partitions. The wasted
memory is unfortunate, though.
Cc: Paul Mackerras <pau...@samba.org>
Cc: Anton Blanchard <an...@samba.org>
Cc: linuxppc-...@ozlabs.org
arch/powerpc/platforms/pseries/setup.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/setup.c
b/arch/powerpc/platforms/pseries/setup.c
index 0007241..7df5ddb 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -39,6 +39,7 @@
#include <linux/irq.h>
#include <linux/seq_file.h>
#include <linux/root_dev.h>
+#include <linux/memblock.h>
#include <asm/mmu.h>
#include <asm/processor.h>
@@ -293,14 +294,15 @@ static int alloc_dispatch_logs(void)
for_each_possible_cpu(cpu) {
pp = &paca[cpu];
- dtl = kmalloc_node(DISPATCH_LOG_BYTES, GFP_KERNEL,
- cpu_to_node(cpu));
+ dtl = kmalloc_node(DISPATCH_LOG_BYTES + DISPATCH_LOG_BYTES - 1,
+ GFP_KERNEL, cpu_to_node(cpu));
if (!dtl) {
pr_warn("Failed to allocate dispatch trace log for cpu
%d\n",
cpu);
pr_warn("Stolen time statistics will be unreliable\n");
break;
}
+ dtl = PTR_ALIGN(dtl, DISPATCH_LOG_BYTES);
pp->dtl_ridx = 0;
pp->dispatch_log = dtl;
--
1.7.4.1
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