diff options
author | Anton Blanchard <anton@samba.org> | 2013-10-20 10:26:20 +1100 |
---|---|---|
committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-10-30 16:01:43 +1100 |
commit | 733187e29576041ceccf3b82092ca900fc929170 (patch) | |
tree | 726795008263fd9d5f01a020a3d60f2d04d353e3 /arch/powerpc/include/asm/lppaca.h | |
parent | dbc2fbd7c29a78724e761711d516930246c0e1c2 (diff) | |
download | linux-733187e29576041ceccf3b82092ca900fc929170.tar.bz2 |
powerpc/pseries: Fix dedicated processor partition detection
commit f13c13a00512 (powerpc: Stop using non-architected shared_proc
field in lppaca) fixed a potential issue with shared/dedicated
partition detection. The old method of detection relied on an
unarchitected field (shared_proc), and this patch switched
to using something architected (a non zero yield_count).
Unfortunately the assertion in the Linux header that yield_count
is only non zero on shared processor partitions is not true. It
turns out dedicated processor partitions can increment yield_count
and as such we falsely detect dedicated partitions as shared.
Fix the comment, and switch back to using the old method.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/include/asm/lppaca.h')
-rw-r--r-- | arch/powerpc/include/asm/lppaca.h | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/arch/powerpc/include/asm/lppaca.h b/arch/powerpc/include/asm/lppaca.h index 4470d1e34d23..844c28de7ec0 100644 --- a/arch/powerpc/include/asm/lppaca.h +++ b/arch/powerpc/include/asm/lppaca.h @@ -84,8 +84,8 @@ struct lppaca { * the processor is yielded (either because of an OS yield or a * hypervisor preempt). An even value implies that the processor is * currently executing. - * NOTE: This value will ALWAYS be zero for dedicated processors and - * will NEVER be zero for shared processors (ie, initialized to a 1). + * NOTE: Even dedicated processor partitions can yield so this + * field cannot be used to determine if we are shared or dedicated. */ volatile __be32 yield_count; volatile __be32 dispersion_count; /* dispatch changed physical cpu */ @@ -106,15 +106,15 @@ extern struct lppaca lppaca[]; #define lppaca_of(cpu) (*paca[cpu].lppaca_ptr) /* - * Old kernels used a reserved bit in the VPA to determine if it was running - * in shared processor mode. New kernels look for a non zero yield count - * but KVM still needs to set the bit to keep the old stuff happy. + * We are using a non architected field to determine if a partition is + * shared or dedicated. This currently works on both KVM and PHYP, but + * we will have to transition to something better. */ #define LPPACA_OLD_SHARED_PROC 2 static inline bool lppaca_shared_proc(struct lppaca *l) { - return l->yield_count != 0; + return !!(l->__old_status & LPPACA_OLD_SHARED_PROC); } /* |