From: James Morse james.morse@arm.com
maillist inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8XMTL CVE: NA
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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 Tested-by: Miguel Luis miguel.luis@oracle.com Tested-by: Vishnu Pajjuri vishnu@os.amperecomputing.com Tested-by: Jianyong Wu jianyong.wu@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) Reviewed-by: Jonathan Cameron Jonathan.Cameron@huawei.com
Signed-off-by: liwei liwei728@huawei.com --- drivers/irqchip/irq-gic-v3.c | 14 ++++++++++++++ include/linux/acpi.h | 2 +- 2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c index 125198c69ae0..d49d6e62f869 100644 --- a/drivers/irqchip/irq-gic-v3.c +++ b/drivers/irqchip/irq-gic-v3.c @@ -2391,11 +2391,25 @@ gic_acpi_parse_madt_gicc(union acpi_subtable_headers *header, (struct acpi_madt_generic_interrupt *)header; u32 reg = readl_relaxed(acpi_data.dist_base + GICD_PIDR2) & GIC_PIDR2_ARCH_MASK; u32 size = reg == GIC_PIDR2_ARCH_GICv4 ? SZ_64K * 4 : SZ_64K * 2; + int cpu = get_cpu_for_acpi_id(gicc->uid); void __iomem *redist_base;
if (!acpi_gicc_is_usable(gicc)) return 0;
+ /* + * Capable but disabled CPUs can be brought online later. What about + * the redistributor? ACPI doesn't want to say! + * Virtual hotplug systems can use the MADT's "always-on" GICR entries. + * Otherwise, prevent such CPUs from being brought online. + */ + if (!(gicc->flags & ACPI_MADT_ENABLED)) { + pr_warn_once("CPU %u's redistributor is inaccessible: this CPU can't be brought online\n", cpu); + set_cpu_present(cpu, false); + set_cpu_possible(cpu, false); + return 0; + } + redist_base = ioremap(gicc->gicr_base_address, size); if (!redist_base) return -ENOMEM; diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 320da5e762ab..d7a85792fef6 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -258,7 +258,7 @@ void acpi_table_print_madt_entry (struct acpi_subtable_header *madt);
static inline bool acpi_gicc_is_usable(struct acpi_madt_generic_interrupt *gicc) { - return gicc->flags & ACPI_MADT_ENABLED; + return gicc->flags & (ACPI_MADT_ENABLED | ACPI_MADT_GICC_CPU_CAPABLE); }
/* the following numa functions are architecture-dependent */