summaryrefslogtreecommitdiff
path: root/drivers/firmware/psci/psci.c
diff options
context:
space:
mode:
authorJames Morse <james.morse@arm.com>2021-07-05 11:37:09 +0100
committerRussell King (Oracle) <rmk+kernel@armlinux.org.uk>2023-10-23 19:59:43 +0100
commit98b81fa9cd26892578f24afb19fd734baaeab4ee (patch)
treeff06fb895b71e604203ea21c88d51bd9c3c7d00e /drivers/firmware/psci/psci.c
parent05608bc12e9687f6589b2fa9fdb78daec3e3e6ef (diff)
irqchip/gic-v3: Add support for ACPI's disabled but 'online capable' CPUs
To support virtual CPU hotplug, ACPI has added an 'online capable' bit to the MADT GICC entries. This indicates a disabled CPU entry may not be possible to online via PSCI until firmware has set enabled bit in _STA. What about the redistributor in the GICC entry? ACPI doesn't want to say. Assume the worst: When a redistributor is described in the GICC entry, but the entry is marked as disabled at boot, assume the redistributor is inaccessible. The GICv3 driver doesn't support late online of redistributors, so this means the corresponding CPU can't be brought online either. Clear the possible and present bits. Systems that want CPU hotplug in a VM can ensure their redistributors are always-on, and describe them that way with a GICR entry in the MADT. When mapping redistributors found via GICC entries, handle the case where the arch code believes the CPU is present and possible, but it does not have an accessible redistributor. Print a warning and clear the present and possible bits. Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> ---- Disabled but online-capable CPUs cause this message to be printed if their redistributors are described via GICC: | GICv3: CPU 3's redistributor is inaccessible: this CPU can't be brought online If ACPI's _STA tries to make the cpu present later, this message is printed: | Changing CPU present bit is not supported Changes since RFC v2: * use gicc->flags & (ACPI_MADT_ENABLED | ACPI_MADT_GICC_CPU_CAPABLE)
Diffstat (limited to 'drivers/firmware/psci/psci.c')
0 files changed, 0 insertions, 0 deletions