Hi Bin,
On Sun, 12 Jul 2020 at 22:56, Bin Meng bmeng.cn@gmail.com wrote:
Hi Simon,
On Wed, Jul 8, 2020 at 9:37 AM Simon Glass sjg@chromium.org wrote:
Add a way to run a function on a selection of CPUs. This supports either a single CPU, all CPUs, just the main CPU or just the 'APs', in Intel terminology.
It works by writing into a mailbox and then waiting for the CPUs to notice it, take action and indicate they are done.
When SMP is not yet enabled, this just calls the function on the main CPU.
Signed-off-by: Simon Glass sjg@chromium.org Reviewed-by: Wolfgang Wallner wolfgang.wallner@br-automation.com
Changes in v4:
- Only enable this feature of CONFIG_SMP_AP_WORK is enabled
- Allow running on the BSP if SMP is not enabled
Changes in v3:
- Add a comment to run_ap_work()
- Rename flag to GD_FLG_SMP_READY
- Update the comment for run_ap_work() to explain logical_cpu_number
- Clarify meaning of @cpu_select in mp_run_on_cpus() comment
arch/x86/cpu/mp_init.c | 107 +++++++++++++++++++++++++++++++++++--- arch/x86/include/asm/mp.h | 33 ++++++++++++ 2 files changed, 134 insertions(+), 6 deletions(-)
diff --git a/arch/x86/cpu/mp_init.c b/arch/x86/cpu/mp_init.c index 69a23829b9..dd6d6bfab7 100644 --- a/arch/x86/cpu/mp_init.c +++ b/arch/x86/cpu/mp_init.c @@ -54,12 +54,7 @@ struct mp_flight_plan {
callback*/ struct mp_callback {
/*** func() - Function to call on the AP** @arg: Argument to pass*/void (*func)(void *arg);
mp_run_func func; void *arg; int logical_cpu_number;}; @@ -514,6 +509,70 @@ static void store_callback(struct mp_callback **slot, struct mp_callback *val) dmb(); }
+/**
- run_ap_work() - Run a callback on selected APs
- This writes @callback to all APs and waits for them all to acknowledge it,
- Note that whether each AP actually calls the callback depends on the value
- of logical_cpu_number (see struct mp_callback). The logical CPU number is
- the CPU device's req->seq value.
- @callback: Callback information to pass to all APs
- @bsp: CPU device for the BSP
- @num_cpus: The number of CPUs in the system (= number of APs + 1)
- @expire_ms: Timeout to wait for all APs to finish, in milliseconds, or 0 for
no timeout
- @return 0 if OK, -ETIMEDOUT if one or more APs failed to respond in time
- */
+static int run_ap_work(struct mp_callback *callback, struct udevice *bsp,
int num_cpus, uint expire_ms)+{
int cur_cpu = bsp->req_seq;int num_aps = num_cpus - 1; /* number of non-BSPs to get this message */int cpus_accepted;ulong start;int i;if (!IS_ENABLED(CONFIG_SMP_AP_WORK)) {printf("APs already parked. CONFIG_SMP_AP_WORK not enabled\n");return -ENOTSUPP;}/* Signal to all the APs to run the func. */for (i = 0; i < num_cpus; i++) {if (cur_cpu != i)store_callback(&ap_callbacks[i], callback);}mfence();/* Wait for all the APs to signal back that call has been accepted. */start = get_timer(0);do {mdelay(1);cpus_accepted = 0;for (i = 0; i < num_cpus; i++) {if (cur_cpu == i)continue;if (!read_callback(&ap_callbacks[i]))cpus_accepted++;It looks my previous comments were not addressed. I believe there is a bug here that cpus_accepted will double count for the 2nd time in the do {} while () loop.
I thought I replied to that. I don't see how that can happen since it is set to zero each time around the outer loop. Can you please speed it out?
}if (expire_ms && get_timer(start) >= expire_ms) {log(UCLASS_CPU, LOGL_CRIT,"AP call expired; %d/%d CPUs accepted\n",cpus_accepted, num_aps);return -ETIMEDOUT;}} while (cpus_accepted != num_aps);/* Make sure we can see any data written by the APs */mfence();return 0;+}
Regards, Simon