On 9/15/23 02:01, Jonathan Cameron wrote:
On Wed, 13 Sep 2023 16:38:19 +0000
James Morse <james.morse@xxxxxxx> wrote:
From: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
When a CPU is marked as disabled, but online capable in the MADT, PSCI
applies some firmware policy to control when it can be brought online.
PSCI returns DENIED to a CPU_ON request if this is not currently
permitted. The OS can learn the current policy from the _STA enabled bit.
Handle the PSCI DENIED return code gracefully instead of printing an
error.
Specification reference would be good particularly as it's only been
added as a possibility fairly recently.
https://developer.arm.com/documentation/den0022/f/?lang=en page-58
It seems DENIED is the best matched indicator.
Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
[ morse: Rewrote commit message ]
Signed-off-by: James Morse <james.morse@xxxxxxx>
---
arch/arm64/kernel/psci.c | 2 +-
arch/arm64/kernel/smp.c | 3 ++-
drivers/firmware/psci/psci.c | 2 ++
3 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index 29a8e444db83..4fcc0cdd757b 100644
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -40,7 +40,7 @@ static int cpu_psci_cpu_boot(unsigned int cpu)
{
phys_addr_t pa_secondary_entry = __pa_symbol(secondary_entry);
int err = psci_ops.cpu_on(cpu_logical_map(cpu), pa_secondary_entry);
- if (err)
+ if (err && err != -EPROBE_DEFER)
Hmm. EPROBE_DEFER has very specific meaning around driver requesting a retry
when some other bit of the system has finished booting.
I'm not sure it's a good idea for this use case. Maybe just keep to EPERM
as psci_to_linux_errno() will return anyway. Seems valid to me, or
is the requirement to use EPROBE_DEFER coming from further up the stack?
I agree with Jonathan that -EPERM from psci_to_linux_errno(DENIED) is
good enough here. Actually, I think we need to bail from bringing up
the CPU once error is raised on psci_ops.cpu_on() and avoid reporting
it as error with help of -EPROBE_DEFER. -EPERM can serve the same
purpose.
pr_err("failed to boot CPU%d (%d)\n", cpu, err);
return err;
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 8c8f55721786..e958db987665 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -124,7 +124,8 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
/* Now bring the CPU into our world */
ret = boot_secondary(cpu, idle);
if (ret) {
- pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
+ if (ret != -EPROBE_DEFER)
+ pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
return ret;
}
diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
index d9629ff87861..f7ab3fed3528 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -218,6 +218,8 @@ static int __psci_cpu_on(u32 fn, unsigned long cpuid, unsigned long entry_point)
int err;
err = invoke_psci_fn(fn, cpuid, entry_point, 0);
+ if (err == PSCI_RET_DENIED)
+ return -EPROBE_DEFER;
return psci_to_linux_errno(err);
}
Thanks,
Gavin
