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authorLinus Torvalds <torvalds@linux-foundation.org>2024-07-15 17:06:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2024-07-15 17:06:19 -0700
commitc89d780cc195a63dcd9c3d2fc239308b3920a9a1 (patch)
tree21022c5d078e67aba9cca442d05727b898ba27ef /Documentation/arch
parentbbb3556c014dc8ed1645b725ad84477603553743 (diff)
parent4f3a6c4de7d932be94cde2c52ae58feeec9c9dbf (diff)
Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Catalin Marinas: "The biggest part is the virtual CPU hotplug that touches ACPI, irqchip. We also have some GICv3 optimisation for pseudo-NMIs that has been queued via the arm64 tree. Otherwise the usual perf updates, kselftest, various small cleanups. Core: - Virtual CPU hotplug support for arm64 ACPI systems - cpufeature infrastructure cleanups and making the FEAT_ECBHB ID bits visible to guests - CPU errata: expand the speculative SSBS workaround to more CPUs - GICv3, use compile-time PMR values: optimise the way regular IRQs are masked/unmasked when GICv3 pseudo-NMIs are used, removing the need for a static key in fast paths by using a priority value chosen dynamically at boot time ACPI: - 'acpi=nospcr' option to disable SPCR as default console for arm64 - Move some ACPI code (cpuidle, FFH) to drivers/acpi/arm64/ Perf updates: - Rework of the IMX PMU driver to enable support for I.MX95 - Enable support for tertiary match groups in the CMN PMU driver - Initial refactoring of the CPU PMU code to prepare for the fixed instruction counter introduced by Arm v9.4 - Add missing PMU driver MODULE_DESCRIPTION() strings - Hook up DT compatibles for recent CPU PMUs Kselftest updates: - Kernel mode NEON fp-stress - Cleanups, spelling mistakes Miscellaneous: - arm64 Documentation update with a minor clarification on TBI - Fix missing IPI statistics - Implement raw_smp_processor_id() using thread_info rather than a per-CPU variable (better code generation) - Make MTE checking of in-kernel asynchronous tag faults conditional on KASAN being enabled - Minor cleanups, typos" * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (69 commits) selftests: arm64: tags: remove the result script selftests: arm64: tags_test: conform test to TAP output perf: add missing MODULE_DESCRIPTION() macros arm64: smp: Fix missing IPI statistics irqchip/gic-v3: Fix 'broken_rdists' unused warning when !SMP and !ACPI ACPI: Add acpi=nospcr to disable ACPI SPCR as default console on ARM64 Documentation: arm64: Update memory.rst for TBI arm64/cpufeature: Replace custom macros with fields from ID_AA64PFR0_EL1 KVM: arm64: Replace custom macros with fields from ID_AA64PFR0_EL1 perf: arm_pmuv3: Include asm/arm_pmuv3.h from linux/perf/arm_pmuv3.h perf: arm_v6/7_pmu: Drop non-DT probe support perf/arm: Move 32-bit PMU drivers to drivers/perf/ perf: arm_pmuv3: Drop unnecessary IS_ENABLED(CONFIG_ARM64) check perf: arm_pmuv3: Avoid assigning fixed cycle counter with threshold arm64: Kconfig: Fix dependencies to enable ACPI_HOTPLUG_CPU perf: imx_perf: add support for i.MX95 platform perf: imx_perf: fix counter start and config sequence perf: imx_perf: refactor driver for imx93 perf: imx_perf: let the driver manage the counter usage rather the user perf: imx_perf: add macro definitions for parsing config attr ...
Diffstat (limited to 'Documentation/arch')
-rw-r--r--Documentation/arch/arm64/cpu-hotplug.rst79
-rw-r--r--Documentation/arch/arm64/index.rst1
-rw-r--r--Documentation/arch/arm64/memory.rst42
-rw-r--r--Documentation/arch/arm64/silicon-errata.rst16
4 files changed, 115 insertions, 23 deletions
diff --git a/Documentation/arch/arm64/cpu-hotplug.rst b/Documentation/arch/arm64/cpu-hotplug.rst
new file mode 100644
index 000000000000..76ba8d932c72
--- /dev/null
+++ b/Documentation/arch/arm64/cpu-hotplug.rst
@@ -0,0 +1,79 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. _cpuhp_index:
+
+====================
+CPU Hotplug and ACPI
+====================
+
+CPU hotplug in the arm64 world is commonly used to describe the kernel taking
+CPUs online/offline using PSCI. This document is about ACPI firmware allowing
+CPUs that were not available during boot to be added to the system later.
+
+``possible`` and ``present`` refer to the state of the CPU as seen by linux.
+
+
+CPU Hotplug on physical systems - CPUs not present at boot
+----------------------------------------------------------
+
+Physical systems need to mark a CPU that is ``possible`` but not ``present`` as
+being ``present``. An example would be a dual socket machine, where the package
+in one of the sockets can be replaced while the system is running.
+
+This is not supported.
+
+In the arm64 world CPUs are not a single device but a slice of the system.
+There are no systems that support the physical addition (or removal) of CPUs
+while the system is running, and ACPI is not able to sufficiently describe
+them.
+
+e.g. New CPUs come with new caches, but the platform's cache toplogy is
+described in a static table, the PPTT. How caches are shared between CPUs is
+not discoverable, and must be described by firmware.
+
+e.g. The GIC redistributor for each CPU must be accessed by the driver during
+boot to discover the system wide supported features. ACPI's MADT GICC
+structures can describe a redistributor associated with a disabled CPU, but
+can't describe whether the redistributor is accessible, only that it is not
+'always on'.
+
+arm64's ACPI tables assume that everything described is ``present``.
+
+
+CPU Hotplug on virtual systems - CPUs not enabled at boot
+---------------------------------------------------------
+
+Virtual systems have the advantage that all the properties the system will
+ever have can be described at boot. There are no power-domain considerations
+as such devices are emulated.
+
+CPU Hotplug on virtual systems is supported. It is distinct from physical
+CPU Hotplug as all resources are described as ``present``, but CPUs may be
+marked as disabled by firmware. Only the CPU's online/offline behaviour is
+influenced by firmware. An example is where a virtual machine boots with a
+single CPU, and additional CPUs are added once a cloud orchestrator deploys
+the workload.
+
+For a virtual machine, the VMM (e.g. Qemu) plays the part of firmware.
+
+Virtual hotplug is implemented as a firmware policy affecting which CPUs can be
+brought online. Firmware can enforce its policy via PSCI's return codes. e.g.
+``DENIED``.
+
+The ACPI tables must describe all the resources of the virtual machine. CPUs
+that firmware wishes to disable either from boot (or later) should not be
+``enabled`` in the MADT GICC structures, but should have the ``online capable``
+bit set, to indicate they can be enabled later. The boot CPU must be marked as
+``enabled``. The 'always on' GICR structure must be used to describe the
+redistributors.
+
+CPUs described as ``online capable`` but not ``enabled`` can be set to enabled
+by the DSDT's Processor object's _STA method. On virtual systems the _STA method
+must always report the CPU as ``present``. Changes to the firmware policy can
+be notified to the OS via device-check or eject-request.
+
+CPUs described as ``enabled`` in the static table, should not have their _STA
+modified dynamically by firmware. Soft-restart features such as kexec will
+re-read the static properties of the system from these static tables, and
+may malfunction if these no longer describe the running system. Linux will
+re-discover the dynamic properties of the system from the _STA method later
+during boot.
diff --git a/Documentation/arch/arm64/index.rst b/Documentation/arch/arm64/index.rst
index d08e924204bf..78544de0a8a9 100644
--- a/Documentation/arch/arm64/index.rst
+++ b/Documentation/arch/arm64/index.rst
@@ -13,6 +13,7 @@ ARM64 Architecture
asymmetric-32bit
booting
cpu-feature-registers
+ cpu-hotplug
elf_hwcaps
hugetlbpage
kdump
diff --git a/Documentation/arch/arm64/memory.rst b/Documentation/arch/arm64/memory.rst
index 55a55f30eed8..8a658984b8bb 100644
--- a/Documentation/arch/arm64/memory.rst
+++ b/Documentation/arch/arm64/memory.rst
@@ -18,12 +18,10 @@ ARMv8.2 adds optional support for Large Virtual Address space. This is
only available when running with a 64KB page size and expands the
number of descriptors in the first level of translation.
-User addresses have bits 63:48 set to 0 while the kernel addresses have
-the same bits set to 1. TTBRx selection is given by bit 63 of the
-virtual address. The swapper_pg_dir contains only kernel (global)
-mappings while the user pgd contains only user (non-global) mappings.
-The swapper_pg_dir address is written to TTBR1 and never written to
-TTBR0.
+TTBRx selection is given by bit 55 of the virtual address. The
+swapper_pg_dir contains only kernel (global) mappings while the user pgd
+contains only user (non-global) mappings. The swapper_pg_dir address is
+written to TTBR1 and never written to TTBR0.
AArch64 Linux memory layout with 4KB pages + 4 levels (48-bit)::
@@ -65,14 +63,14 @@ Translation table lookup with 4KB pages::
+--------+--------+--------+--------+--------+--------+--------+--------+
|63 56|55 48|47 40|39 32|31 24|23 16|15 8|7 0|
+--------+--------+--------+--------+--------+--------+--------+--------+
- | | | | | |
- | | | | | v
- | | | | | [11:0] in-page offset
- | | | | +-> [20:12] L3 index
- | | | +-----------> [29:21] L2 index
- | | +---------------------> [38:30] L1 index
- | +-------------------------------> [47:39] L0 index
- +-------------------------------------------------> [63] TTBR0/1
+ | | | | | |
+ | | | | | v
+ | | | | | [11:0] in-page offset
+ | | | | +-> [20:12] L3 index
+ | | | +-----------> [29:21] L2 index
+ | | +---------------------> [38:30] L1 index
+ | +-------------------------------> [47:39] L0 index
+ +----------------------------------------> [55] TTBR0/1
Translation table lookup with 64KB pages::
@@ -80,14 +78,14 @@ Translation table lookup with 64KB pages::
+--------+--------+--------+--------+--------+--------+--------+--------+
|63 56|55 48|47 40|39 32|31 24|23 16|15 8|7 0|
+--------+--------+--------+--------+--------+--------+--------+--------+
- | | | | |
- | | | | v
- | | | | [15:0] in-page offset
- | | | +----------> [28:16] L3 index
- | | +--------------------------> [41:29] L2 index
- | +-------------------------------> [47:42] L1 index (48-bit)
- | [51:42] L1 index (52-bit)
- +-------------------------------------------------> [63] TTBR0/1
+ | | | | |
+ | | | | v
+ | | | | [15:0] in-page offset
+ | | | +----------> [28:16] L3 index
+ | | +--------------------------> [41:29] L2 index
+ | +-------------------------------> [47:42] L1 index (48-bit)
+ | [51:42] L1 index (52-bit)
+ +----------------------------------------> [55] TTBR0/1
When using KVM without the Virtualization Host Extensions, the
diff --git a/Documentation/arch/arm64/silicon-errata.rst b/Documentation/arch/arm64/silicon-errata.rst
index eb8af8032c31..bb83c5d8c675 100644
--- a/Documentation/arch/arm64/silicon-errata.rst
+++ b/Documentation/arch/arm64/silicon-errata.rst
@@ -132,16 +132,26 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A710 | #2224489 | ARM64_ERRATUM_2224489 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-A710 | #3324338 | ARM64_ERRATUM_3194386 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A715 | #2645198 | ARM64_ERRATUM_2645198 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-A720 | #3456091 | ARM64_ERRATUM_3194386 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-X1 | #1502854 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-X2 | #2119858 | ARM64_ERRATUM_2119858 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-X2 | #2224489 | ARM64_ERRATUM_2224489 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-X2 | #3324338 | ARM64_ERRATUM_3194386 |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-X3 | #3324335 | ARM64_ERRATUM_3194386 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-X4 | #3194386 | ARM64_ERRATUM_3194386 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-X925 | #3324334 | ARM64_ERRATUM_3194386 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1349291 | N/A |
@@ -156,9 +166,13 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N2 | #2253138 | ARM64_ERRATUM_2253138 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Neoverse-N2 | #3324339 | ARM64_ERRATUM_3194386 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-V1 | #1619801 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
-| ARM | Neoverse-V3 | #3312417 | ARM64_ERRATUM_3312417 |
+| ARM | Neoverse-V2 | #3324336 | ARM64_ERRATUM_3194386 |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM | Neoverse-V3 | #3312417 | ARM64_ERRATUM_3194386 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | MMU-500 | #841119,826419 | N/A |
+----------------+-----------------+-----------------+-----------------------------+