Pull RISC-V updates from Palmer Dabbelt:
- The sub-architecture selection Kconfig system has been cleaned up,
the documentation has been improved, and various detections have been
fixed
- The vector-related extensions dependencies are now validated when
parsing from device tree and in the DT bindings
- Misaligned access probing can be overridden via a kernel command-line
parameter, along with various fixes to misalign access handling
- Support for relocatable !MMU kernels builds
- Support for hpge pfnmaps, which should improve TLB utilization
- Support for runtime constants, which improves the d_hash()
performance
- Support for bfloat16, Zicbom, Zaamo, Zalrsc, Zicntr, Zihpm
- Various fixes, including:
- We were missing a secondary mmu notifier call when flushing the
tlb which is required for IOMMU
- Fix ftrace panics by saving the registers as expected by ftrace
- Fix a couple of stimecmp usage related to cpu hotplug
- purgatory_start is now aligned as per the STVEC requirements
- A fix for hugetlb when calculating the size of non-present PTEs
* tag 'riscv-for-linus-6.15-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (65 commits)
riscv: Add norvc after .option arch in runtime const
riscv: Make sure toolchain supports zba before using zba instructions
riscv/purgatory: 4B align purgatory_start
riscv/kexec_file: Handle R_RISCV_64 in purgatory relocator
selftests: riscv: fix v_exec_initval_nolibc.c
riscv: Fix hugetlb retrieval of number of ptes in case of !present pte
riscv: print hartid on bringup
riscv: Add norvc after .option arch in runtime const
riscv: Remove CONFIG_PAGE_OFFSET
riscv: Support CONFIG_RELOCATABLE on riscv32
asm-generic: Always define Elf_Rel and Elf_Rela
riscv: Support CONFIG_RELOCATABLE on NOMMU
riscv: Allow NOMMU kernels to access all of RAM
riscv: Remove duplicate CONFIG_PAGE_OFFSET definition
RISC-V: errata: Use medany for relocatable builds
dt-bindings: riscv: document vector crypto requirements
dt-bindings: riscv: add vector sub-extension dependencies
dt-bindings: riscv: d requires f
RISC-V: add f & d extension validation checks
RISC-V: add vector crypto extension validation checks
...
Charlie Jenkins <charlie@rivosinc.com> says:
xtheadvector is a custom extension that is based upon riscv vector
version 0.7.1 [1]. All of the vector routines have been modified to
support this alternative vector version based upon whether xtheadvector
was determined to be supported at boot.
vlenb is not supported on the existing xtheadvector hardware, so a
devicetree property thead,vlenb is added to provide the vlenb to Linux.
There is a new hwprobe key RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0 that is
used to request which thead vendor extensions are supported on the
current platform. This allows future vendors to allocate hwprobe keys
for their vendor.
Support for xtheadvector is also added to the vector kselftests.
[1] 95358cb2cc/xtheadvector.adoc
* b4-shazam-merge:
riscv: Add ghostwrite vulnerability
selftests: riscv: Support xtheadvector in vector tests
selftests: riscv: Fix vector tests
riscv: hwprobe: Document thead vendor extensions and xtheadvector extension
riscv: hwprobe: Add thead vendor extension probing
riscv: vector: Support xtheadvector save/restore
riscv: Add xtheadvector instruction definitions
riscv: csr: Add CSR encodings for CSR_VXRM/CSR_VXSAT
RISC-V: define the elements of the VCSR vector CSR
riscv: vector: Use vlenb from DT for thead
riscv: Add thead and xtheadvector as a vendor extension
riscv: dts: allwinner: Add xtheadvector to the D1/D1s devicetree
dt-bindings: cpus: add a thead vlen register length property
dt-bindings: riscv: Add xtheadvector ISA extension description
Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20241113-xtheadvector-v11-0-236c22791ef9@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Add a new hwprobe key "RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0" which
allows userspace to probe for the new RISCV_ISA_VENDOR_EXT_XTHEADVECTOR
vendor extension.
This new key will allow userspace code to probe for which thead vendor
extensions are supported. This API is modeled to be consistent with
RISCV_HWPROBE_KEY_IMA_EXT_0. The bitmask returned will have each bit
corresponding to a supported thead vendor extension of the cpumask set.
Just like RISCV_HWPROBE_KEY_IMA_EXT_0, this allows a userspace program
to determine all of the supported thead vendor extensions in one call.
Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Evan Green <evan@rivosinc.com>
Tested-by: Yangyu Chen <cyy@cyyself.name>
Link: https://lore.kernel.org/r/20241113-xtheadvector-v11-10-236c22791ef9@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Pull RISC-v updates from Palmer Dabbelt:
- Support for pointer masking in userspace
- Support for probing vector misaligned access performance
- Support for qspinlock on systems with Zacas and Zabha
* tag 'riscv-for-linus-6.13-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (38 commits)
RISC-V: Remove unnecessary include from compat.h
riscv: Fix default misaligned access trap
riscv: Add qspinlock support
dt-bindings: riscv: Add Ziccrse ISA extension description
riscv: Add ISA extension parsing for Ziccrse
asm-generic: ticket-lock: Add separate ticket-lock.h
asm-generic: ticket-lock: Reuse arch_spinlock_t of qspinlock
riscv: Implement xchg8/16() using Zabha
riscv: Implement arch_cmpxchg128() using Zacas
riscv: Improve zacas fully-ordered cmpxchg()
riscv: Implement cmpxchg8/16() using Zabha
dt-bindings: riscv: Add Zabha ISA extension description
riscv: Implement cmpxchg32/64() using Zacas
riscv: Do not fail to build on byte/halfword operations with Zawrs
riscv: Move cpufeature.h macros into their own header
KVM: riscv: selftests: Add Smnpm and Ssnpm to get-reg-list test
RISC-V: KVM: Allow Smnpm and Ssnpm extensions for guests
riscv: hwprobe: Export the Supm ISA extension
riscv: selftests: Add a pointer masking test
riscv: Allow ptrace control of the tagged address ABI
...
Samuel Holland <samuel.holland@sifive.com> says:
RISC-V defines three extensions for pointer masking[1]:
- Smmpm: configured in M-mode, affects M-mode
- Smnpm: configured in M-mode, affects the next lower mode (S or U-mode)
- Ssnpm: configured in S-mode, affects the next lower mode (VS, VU, or U-mode)
This series adds support for configuring Smnpm or Ssnpm (depending on
which privilege mode the kernel is running in) to allow pointer masking
in userspace (VU or U-mode), extending the PR_SET_TAGGED_ADDR_CTRL API
from arm64. Unlike arm64 TBI, userspace pointer masking is not enabled
by default on RISC-V. Additionally, the tag width (referred to as PMLEN)
is variable, so userspace needs to ask the kernel for a specific tag
width, which is interpreted as a lower bound on the number of tag bits.
This series also adds support for a tagged address ABI similar to arm64
and x86. Since accesses from the kernel to user memory use the kernel's
pointer masking configuration, not the user's, the kernel must untag
user pointers in software before dereferencing them. And since the tag
width is variable, as with LAM on x86, it must be kept the same across
all threads in a process so untagged_addr_remote() can work.
[1]: https://github.com/riscv/riscv-j-extension/raw/d70011dde6c2/zjpm-spec.pdf
* b4-shazam-merge:
KVM: riscv: selftests: Add Smnpm and Ssnpm to get-reg-list test
RISC-V: KVM: Allow Smnpm and Ssnpm extensions for guests
riscv: hwprobe: Export the Supm ISA extension
riscv: selftests: Add a pointer masking test
riscv: Allow ptrace control of the tagged address ABI
riscv: Add support for the tagged address ABI
riscv: Add support for userspace pointer masking
riscv: Add CSR definitions for pointer masking
riscv: Add ISA extension parsing for pointer masking
dt-bindings: riscv: Add pointer masking ISA extensions
Link: https://lore.kernel.org/r/20241016202814.4061541-1-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Supm is a virtual ISA extension defined in the RISC-V Pointer Masking
specification, which indicates that pointer masking is available in
U-mode. It can be provided by either Smnpm or Ssnpm, depending on which
mode the kernel runs in. Userspace should not care about this
distinction, so export Supm instead of either underlying extension.
Hide the extension if the kernel was compiled without support for the
pointer masking prctl() interface.
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Link: https://lore.kernel.org/r/20241016202814.4061541-9-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
In preparation for misaligned vector performance hwprobe keys, rename
the hwprobe key values associated with misaligned scalar accesses to
include the term SCALAR. Leave the old defines in place to maintain
source compatibility.
This change is intended to be a functional no-op.
Signed-off-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20240809214444.3257596-3-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
RISCV_HWPROBE_KEY_CPUPERF_0 was mistakenly flagged as a bitmask in
hwprobe_key_is_bitmask(), when in reality it was an enum value. This
causes problems when used in conjunction with RISCV_HWPROBE_WHICH_CPUS,
since SLOW, FAST, and EMULATED have values whose bits overlap with
each other. If the caller asked for the set of CPUs that was SLOW or
EMULATED, the returned set would also include CPUs that were FAST.
Introduce a new hwprobe key, RISCV_HWPROBE_KEY_MISALIGNED_PERF, which
returns the same values in response to a direct query (with no flags),
but is properly handled as an enumerated value. As a result, SLOW,
FAST, and EMULATED are all correctly treated as distinct values under
the new key when queried with the WHICH_CPUS flag.
Leave the old key in place to avoid disturbing applications which may
have already come to rely on the key, with or without its broken
behavior with respect to the WHICH_CPUS flag.
Fixes: e178bf146e ("RISC-V: hwprobe: Introduce which-cpus flag")
Signed-off-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20240809214444.3257596-2-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The RISC-V architecture makes a real time counter CSR (via RDTIME
instruction) available for applications in U-mode but there is no
architected mechanism for an application to discover the frequency
the counter is running at. Some applications (e.g., DPDK) use the
time counter for basic performance analysis as well as fine grained
time-keeping.
Add support to the hwprobe system call to export the time CSR
frequency to code running in U-mode.
Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
Reviewed-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Acked-by: Punit Agrawal <punit.agrawal@bytedance.com>
Link: https://lore.kernel.org/r/20240702033731.71955-2-cuiyunhui@bytedance.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Andrew Jones <ajones@ventanamicro.com> says:
Zawrs provides two instructions (wrs.nto and wrs.sto), where both are
meant to allow the hart to enter a low-power state while waiting on a
store to a memory location. The instructions also both wait an
implementation-defined "short" duration (unless the implementation
terminates the stall for another reason). The difference is that while
wrs.sto will terminate when the duration elapses, wrs.nto, depending on
configuration, will either just keep waiting or an ILL exception will be
raised. Linux will use wrs.nto, so if platforms have an implementation
which falls in the "just keep waiting" category (which is not expected),
then it should _not_ advertise Zawrs in the hardware description.
Like wfi (and with the same {m,h}status bits to configure it), when
wrs.nto is configured to raise exceptions it's expected that the higher
privilege level will see the instruction was a wait instruction, do
something, and then resume execution following the instruction. For
example, KVM does configure exceptions for wfi (hstatus.VTW=1) and
therefore also for wrs.nto. KVM does this for wfi since it's better to
allow other tasks to be scheduled while a VCPU waits for an interrupt.
For waits such as those where wrs.nto/sto would be used, which are
typically locks, it is also a good idea for KVM to be involved, as it
can attempt to schedule the lock holding VCPU.
This series starts with Christoph's addition of the riscv
smp_cond_load_relaxed function which applies wrs.sto when available.
That patch has been reworked to use wrs.nto and to use the same approach
as Arm for the wait loop, since we can't have arbitrary C code between
the load-reserved and the wrs. Then, hwprobe support is added (since the
instructions are also usable from usermode), and finally KVM is
taught about wrs.nto, allowing guests to see and use the Zawrs
extension.
We still don't have test results from hardware, and it's not possible to
prove that using Zawrs is a win when testing on QEMU, not even when
oversubscribing VCPUs to guests. However, it is possible to use KVM
selftests to force a scenario where we can prove Zawrs does its job and
does it well. [4] is a test which does this and, on my machine, without
Zawrs it takes 16 seconds to complete and with Zawrs it takes 0.25
seconds.
This series is also available here [1]. In order to use QEMU for testing
a build with [2] is needed. In order to enable guests to use Zawrs with
KVM using kvmtool, the branch at [3] may be used.
[1] https://github.com/jones-drew/linux/commits/riscv/zawrs-v3/
[2] https://lore.kernel.org/all/20240312152901.512001-2-ajones@ventanamicro.com/
[3] https://github.com/jones-drew/kvmtool/commits/riscv/zawrs/
[4] cb2beccebc
Link: https://lore.kernel.org/r/20240426100820.14762-8-ajones@ventanamicro.com
* b4-shazam-merge:
KVM: riscv: selftests: Add Zawrs extension to get-reg-list test
KVM: riscv: Support guest wrs.nto
riscv: hwprobe: export Zawrs ISA extension
riscv: Add Zawrs support for spinlocks
dt-bindings: riscv: Add Zawrs ISA extension description
riscv: Provide a definition for 'pause'
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Some userspace applications (OpenJDK for instance) uses the free MSBs
in pointers to insert additional information for their own logic and
need to get this information from somewhere. Currently they rely on
parsing /proc/cpuinfo "mmu=svxx" string to obtain the current value of
virtual address usable bits [1]. Since this reflect the raw supported
MMU mode, it might differ from the logical one used internally which is
why arch_get_mmap_end() is used. Exporting the highest mmapable address
through hwprobe will allow a more stable interface to be used. For that
purpose, add a new hwprobe key named
RISCV_HWPROBE_KEY_HIGHEST_VIRT_ADDRESS which will export the highest
userspace virtual address.
Link: https://github.com/openjdk/jdk/blob/master/src/hotspot/os_cpu/linux_riscv/vm_version_linux_riscv.cpp#L171 [1]
Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20240410144558.1104006-1-cleger@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Make has_vector() to check for ZVE32X. Every in-kernel usage of V that
requires a more complicate version of V must then call out explicitly.
Also, change riscv_v_first_use_handler(), and boot code that calls
riscv_v_setup_vsize() to accept ZVE32X.
Most kernel/user interfaces requires minimum of ZVE32X. Thus, programs
compiled and run with ZVE32X should be supported by the kernel on most
aspects. This includes context-switch, signal, ptrace, prctl, and
hwprobe.
One exception is that ELF_HWCAP returns 'V' only if full V is supported
on the platform. This means that the system without a full V must not
rely on ELF_HWCAP to tell whether it is allowable to execute Vector
without first invoking a prctl() check.
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Acked-by: Joel Granados <j.granados@samsung.com>
Link: https://lore.kernel.org/r/20240510-zve-detection-v5-7-0711bdd26c12@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The following Vector subextensions for "embedded" platforms are added
into RISCV_HWPROBE_KEY_IMA_EXT_0:
- ZVE32X
- ZVE32F
- ZVE64X
- ZVE64F
- ZVE64D
Extensions ending with an X indicates that the platform doesn't have a
vector FPU.
Extensions ending with F/D mean that whether single (F) or double (D)
precision vector operation is supported.
The number 32 or 64 follows from ZVE tells the maximum element length.
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Clément Léger <cleger@rivosinc.com>
Link: https://lore.kernel.org/r/20240510-zve-detection-v5-6-0711bdd26c12@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Clément Léger <cleger@rivosinc.com> says:
This series add support for a few more extensions that are present in
the RVA22U64/RVA23U64 (either mandatory or optional) and that are useful
for userspace:
- Zicond
- Zacas
- Ztso
Series currently based on riscv/for-next.
* b4-shazam-lts:
riscv: hwprobe: export Zicond extension
riscv: hwprobe: export Zacas ISA extension
riscv: add ISA extension parsing for Zacas
dt-bindings: riscv: add Zacas ISA extension description
riscv: hwprobe: export Ztso ISA extension
riscv: add ISA extension parsing for Ztso
Link: https://lore.kernel.org/r/20231220155723.684081-1-cleger@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Andrew Jones <ajones@ventanamicro.com> says:
This series introduces a flag for the hwprobe syscall which effectively
reverses its behavior from getting the values of keys for a set of cpus
to getting the cpus for a set of key-value pairs.
* b4-shazam-merge:
RISC-V: selftests: Add which-cpus hwprobe test
RISC-V: hwprobe: Introduce which-cpus flag
RISC-V: Move the hwprobe syscall to its own file
RISC-V: hwprobe: Clarify cpus size parameter
Link: https://lore.kernel.org/r/20231122164700.127954-6-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Introduce the first flag for the hwprobe syscall. The flag basically
reverses its behavior, i.e. instead of populating the values of keys
for a given set of cpus, the set of cpus after the call is the result
of finding a set which supports the values of the keys. In order to
do this, we implement a pair compare function which takes the type of
value (a single value vs. a bitmask of booleans) into consideration.
We also implement vdso support for the new flag.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Evan Green <evan@rivosinc.com>
Link: https://lore.kernel.org/r/20231122164700.127954-9-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
