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authorGautham R. Shenoy <ego@linux.vnet.ibm.com>2017-05-16 14:19:43 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2017-05-30 14:59:51 +1000
commit5f221c3ca13dceaea8eefe21dbd85da91ed9b1e8 (patch)
tree67390009ff7b8b718e0fddad23289facc2c178d4 /arch/powerpc/platforms
parent518470fe962e23ca69a818e1e507eb4d28b6b09b (diff)
powerpc/powernv/idle: Correctly initialize core_idle_state_ptr
The lower 8 bits of core_idle_state_ptr tracks the number of non-idle threads in the core. This is supposed to be initialized to bit-map corresponding to the threads_per_core. However, currently it is initialized to PNV_CORE_IDLE_THREAD_BITS (0xFF). This is correct for POWER8 which has 8 threads per core, but not for POWER9 which has 4 threads per core. As a result, on POWER9, core_idle_state_ptr gets initialized to 0xFF. In case when all the threads of the core are idle, the bits corresponding tracking the idle-threads are non-zero. As a result, the idle entry/exit code fails to save/restore per-core hypervisor state since it assumes that there are threads in the cores which are still active. Fix this by correctly initializing the lower bits of the core_idle_state_ptr on the basis of threads_per_core. Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/platforms')
-rw-r--r--arch/powerpc/platforms/powernv/idle.c29
1 files changed, 19 insertions, 10 deletions
diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
index 0c21747ed7e0..502f3275d8c2 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -96,15 +96,24 @@ static void pnv_alloc_idle_core_states(void)
u32 *core_idle_state;
/*
- * core_idle_state - First 8 bits track the idle state of each thread
- * of the core. The 8th bit is the lock bit. Initially all thread bits
- * are set. They are cleared when the thread enters deep idle state
- * like sleep and winkle. Initially the lock bit is cleared.
- * The lock bit has 2 purposes
- * a. While the first thread is restoring core state, it prevents
- * other threads in the core from switching to process context.
- * b. While the last thread in the core is saving the core state, it
- * prevents a different thread from waking up.
+ * core_idle_state - The lower 8 bits track the idle state of
+ * each thread of the core.
+ *
+ * The most significant bit is the lock bit.
+ *
+ * Initially all the bits corresponding to threads_per_core
+ * are set. They are cleared when the thread enters deep idle
+ * state like sleep and winkle/stop.
+ *
+ * Initially the lock bit is cleared. The lock bit has 2
+ * purposes:
+ * a. While the first thread in the core waking up from
+ * idle is restoring core state, it prevents other
+ * threads in the core from switching to process
+ * context.
+ * b. While the last thread in the core is saving the
+ * core state, it prevents a different thread from
+ * waking up.
*/
for (i = 0; i < nr_cores; i++) {
int first_cpu = i * threads_per_core;
@@ -112,7 +121,7 @@ static void pnv_alloc_idle_core_states(void)
size_t paca_ptr_array_size;
core_idle_state = kmalloc_node(sizeof(u32), GFP_KERNEL, node);
- *core_idle_state = PNV_CORE_IDLE_THREAD_BITS;
+ *core_idle_state = (1 << threads_per_core) - 1;
paca_ptr_array_size = (threads_per_core *
sizeof(struct paca_struct *));