[PATCH RFC 4/4] arm64: kernel: Arch specific ACPI hooks(like logical cpuid<->hwid etc.)
From: Salil Mehta <hidden>
Date: 2020-06-25 13:44:27
Also in:
kvm, lkml, qemu-arm
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
To support virtual cpu hotplug, some arch specifc hooks must be facilitated. These hooks are called by the generic ACPI cpu hotplug framework during a vcpu hot-(un)plug event handling. The changes required involve: 1. Allocation of the logical cpuid corresponding to the hwid/mpidr 2. Mapping of logical cpuid to hwid/mpidr and marking present 3. Removing vcpu from present mask during hot-unplug 4. For arm64, all possible cpus are registered within topology_init() Hence, we need to override the weak ACPI call of arch_register_cpu() (which returns -ENODEV) and return success. 5. NUMA node mapping set for this vcpu using SRAT Table info during init time will be discarded as the logical cpu-ids used at that time might not be correct. This mapping will be set again using the proximity/node info obtained by evaluating _PXM ACPI method. Note, during hot unplug of vcpu, we do not unmap the association between the logical cpuid and hwid/mpidr. This remains persistent. Signed-off-by: Salil Mehta <redacted> Signed-off-by: Xiongfeng Wang <redacted> --- arch/arm64/kernel/smp.c | 80 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 80 insertions(+)
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 63f31ea23e55..f3315840e829 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c@@ -528,6 +528,86 @@ struct acpi_madt_generic_interrupt *acpi_cpu_get_madt_gicc(int cpu) return &cpu_madt_gicc[cpu]; } +#ifdef CONFIG_ACPI_HOTPLUG_CPU +int arch_register_cpu(int num) +{ + return 0; +} + +static int set_numa_node_for_cpu(acpi_handle handle, int cpu) +{ +#ifdef CONFIG_ACPI_NUMA + int node_id; + + /* will evaluate _PXM */ + node_id = acpi_get_node(handle); + if (node_id != NUMA_NO_NODE) + set_cpu_numa_node(cpu, node_id); +#endif + return 0; +} + +static void unset_numa_node_for_cpu(int cpu) +{ +#ifdef CONFIG_ACPI_NUMA + set_cpu_numa_node(cpu, NUMA_NO_NODE); +#endif +} + +static int allocate_logical_cpuid(u64 physid) +{ + int first_invalid_idx = -1; + bool first = true; + int i; + + for_each_possible_cpu(i) { + /* + * logical cpuid<->hwid association remains persistent once + * established + */ + if (cpu_logical_map(i) == physid) + return i; + + if ((cpu_logical_map(i) == INVALID_HWID) && first) { + first_invalid_idx = i; + first = false; + } + } + + return first_invalid_idx; +} + +int acpi_unmap_cpu(int cpu) +{ + set_cpu_present(cpu, false); + unset_numa_node_for_cpu(cpu); + + return 0; +} + +int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, u32 acpi_id, + int *cpuid) +{ + int cpu; + + cpu = allocate_logical_cpuid(physid); + if (cpu < 0) { + pr_warn("Unable to map logical cpuid to physid 0x%llx\n", + physid); + return -ENOSPC; + } + + /* map the logical cpu id to cpu MPIDR */ + cpu_logical_map(cpu) = physid; + set_numa_node_for_cpu(handle, cpu); + + set_cpu_present(cpu, true); + *cpuid = cpu; + + return 0; +} +#endif + /* * acpi_map_gic_cpu_interface - parse processor MADT entry *
--
2.17.1
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