| Message ID | 20230913163823.7880-32-james.morse@arm.com (mailing list archive) |
|---|---|
| State | RFC, archived |
| Headers | show |
| Series | ACPI/arm64: add support for virtual cpuhotplug | expand |
On Wed, 13 Sep 2023 16:38:19 +0000 James Morse <james.morse@arm.com> wrote: > From: Jean-Philippe Brucker <jean-philippe@linaro.org> > > 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. > > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> > [ morse: Rewrote commit message ] > Signed-off-by: James Morse <james.morse@arm.com> > --- > 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? > 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); > } >
On 9/15/23 02:01, Jonathan Cameron wrote: > On Wed, 13 Sep 2023 16:38:19 +0000 > James Morse <james.morse@arm.com> wrote: > >> From: Jean-Philippe Brucker <jean-philippe@linaro.org> >> >> 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@linaro.org> >> [ morse: Rewrote commit message ] >> Signed-off-by: James Morse <james.morse@arm.com> >> --- >> 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
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) 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); }