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arm64: psci: Ignore DENIED CPUs

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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.

Note the alternatives to the PSCI cpu_boot() callback do not
return -EPERM so the change in smp.c has no affect.

See https://developer.arm.com/documentation/den0022/f/?lang=en page 58.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
[ morse: Rewrote commit message ]
Signed-off-by: James Morse <james.morse@arm.com>
Tested-by: Miguel Luis <miguel.luis@oracle.com>
Tested-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
Tested-by: Jianyong Wu <jianyong.wu@arm.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20240529133446.28446-16-Jonathan.Cameron@huawei.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Jean-Philippe Brucker 2024-05-29 14:34:42 +01:00 committed by Catalin Marinas
parent d633da5d3a
commit 643e12da4a
2 changed files with 3 additions and 2 deletions
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2
arch/arm64/kernel/psci.c
View File

@ -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 != -EPERM)
pr_err("failed to boot CPU%d (%d)\n", cpu, err);
return err;

3
arch/arm64/kernel/smp.c
View File

@ -132,7 +132,8 @@ 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 != -EPERM)
pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
return ret;
}