| Message ID | 20230913163823.7880-31-james.morse@arm.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | ACPI/arm64: add support for virtual cpuhotplug | expand |
| Context | Check | Description |
|---|---|---|
| conchuod/cover_letter | success | Series has a cover letter |
| conchuod/tree_selection | success | Guessed tree name to be for-next at HEAD 0bb80ecc33a8 |
| conchuod/fixes_present | success | Fixes tag not required for -next series |
| conchuod/maintainers_pattern | success | MAINTAINERS pattern errors before the patch: 5 and now 5 |
| conchuod/verify_signedoff | success | Signed-off-by tag matches author and committer |
| conchuod/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| conchuod/build_rv64_clang_allmodconfig | success | Errors and warnings before: 284 this patch: 284 |
| conchuod/module_param | success | Was 0 now: 0 |
| conchuod/build_rv64_gcc_allmodconfig | success | Errors and warnings before: 320 this patch: 320 |
| conchuod/build_rv32_defconfig | success | Build OK |
| conchuod/dtb_warn_rv64 | success | Errors and warnings before: 25 this patch: 25 |
| conchuod/header_inline | success | No static functions without inline keyword in header files |
| conchuod/checkpatch | warning | WARNING: line length of 112 exceeds 100 columns |
| conchuod/build_rv64_nommu_k210_defconfig | success | Build OK |
| conchuod/verify_fixes | success | No Fixes tag |
| conchuod/build_rv64_nommu_virt_defconfig | success | Build OK |
On Wed, Sep 13, 2023 at 04:38:18PM +0000, James Morse wrote: > 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 || > + gicc->flags & ACPI_MADT_GICC_CPU_CAPABLE)); ... and this starts getting silly with the number of parens. return gicc->flags & ACPI_MADT_ENABLED || gicc->flags & ACPI_MADT_GICC_CPU_CAPABLE; is entirely sufficient. Also: return gicc->flags & (ACPI_MADT_ENABLED | ACPI_MADT_GICC_CPU_CAPABLE); also works.
On 9/14/23 18:10, Russell King (Oracle) wrote: > On Wed, Sep 13, 2023 at 04:38:18PM +0000, James Morse wrote: >> 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 || >> + gicc->flags & ACPI_MADT_GICC_CPU_CAPABLE)); > > ... and this starts getting silly with the number of parens. > > return gicc->flags & ACPI_MADT_ENABLED || > gicc->flags & ACPI_MADT_GICC_CPU_CAPABLE; > > is entirely sufficient. Also: > > return gicc->flags & (ACPI_MADT_ENABLED | ACPI_MADT_GICC_CPU_CAPABLE); > > also works. > vote for the second one, which is: gicc->flags & (ACPI_MADT_ENABLED | ACPI_MADT_GICC_CPU_CAPABLE) Thanks, Gavin
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c index 0f54811262eb..f56d064f4aa9 100644 --- a/drivers/irqchip/irq-gic-v3.c +++ b/drivers/irqchip/irq-gic-v3.c @@ -2365,11 +2365,25 @@ 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 e3265a9eafae..92cb25349a18 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -258,7 +258,8 @@ 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 || + gicc->flags & ACPI_MADT_GICC_CPU_CAPABLE)); } /* the following numa functions are architecture-dependent */
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> ---- 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 --- drivers/irqchip/irq-gic-v3.c | 14 ++++++++++++++ include/linux/acpi.h | 3 ++- 2 files changed, 16 insertions(+), 1 deletion(-)