Hi all,
This is a RESEND of v1 to correct a mistake in the CC list. There are **no changes in code** compared to the previous v1.
This patch series adds support for the recently ratified Zilsd (Load/Store pair instructions) and Zclsd (Compressed Load/Store pair instructions) extensions to the RISC-V Linux kernel. It covers device tree binding,ISA string parsing, hwprobe exposure, KVM guest handling and selftests.
Zilsd and Zclsd allow more efficient memory access sequences on RV32. My goal is to enable glibc and other user-space libraries to detect these extensions via hwprobe and make use of them for optimized implementations of common routines. To achieve this, the Linux kernel needs to recognize and expose the availability of these extensions through the device tree bindings, ISA string parsing and hwprobe interfaces. KVM support is also required to correctly virtualize these features for guest environments.
The series is structured as follows: - Patch 1: Add device tree bindings documentation for Zilsd and Zclsd - Patch 2: Extend RISC-V ISA extension string parsing to recognize them. - Patch 3: Export Zilsd and Zclsd via riscv_hwprobe - Patch 4: Allow KVM guests to use them. - Patch 5: Add KVM selftests.
This series of patches is a preparatory step toward enabling user-space optimizations in glibc that leverage Zilsd and Zclsd, by providing the necessary kernel-side support.
Please review, and let me know if any adjustments are needed.
Thanks, Pincheng Wang
Pincheng Wang (5): dt-bidings: riscv: add Zilsd and Zclsd extension descriptions riscv: add ISA extension parsing for Zilsd and Zclsd: riscv: hwprobe: export Zilsd and Zclsd ISA extensions riscv: KVM: allow Zilsd and Zclsd extensions for Guest/VM KVM: riscv: selftests: add Zilsd and Zclsd extension to get-reg-list test
Documentation/arch/riscv/hwprobe.rst | 8 ++++ .../devicetree/bindings/riscv/extensions.yaml | 39 +++++++++++++++++++ arch/riscv/include/asm/hwcap.h | 2 + arch/riscv/include/uapi/asm/hwprobe.h | 2 + arch/riscv/include/uapi/asm/kvm.h | 2 + arch/riscv/kernel/cpufeature.c | 24 ++++++++++++ arch/riscv/kernel/sys_hwprobe.c | 2 + arch/riscv/kvm/vcpu_onereg.c | 2 + .../selftests/kvm/riscv/get-reg-list.c | 6 +++ 9 files changed, 87 insertions(+)
Add descriptions for the Zilsd (Load/Store pair instructions) and Zclsd (Compressed Load/Store pair instructions) ISA extensions which were ratified in commit f88abf1 ("Integrating load/store pair for RV32 with the main manual") of the riscv-isa-manual.
Signed-off-by: Pincheng Wang pincheng.plct@isrc.iscas.ac.cn --- .../devicetree/bindings/riscv/extensions.yaml | 39 +++++++++++++++++++ 1 file changed, 39 insertions(+)
diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml index ede6a58ccf53..d72ffe8f6fa7 100644 --- a/Documentation/devicetree/bindings/riscv/extensions.yaml +++ b/Documentation/devicetree/bindings/riscv/extensions.yaml @@ -366,6 +366,20 @@ properties: guarantee on LR/SC sequences, as ratified in commit b1d806605f87 ("Updated to ratified state.") of the riscv profiles specification.
+ - const: zilsd + description: + The standard Zilsd extension which provides support for aligned + register-pair load and store operations in 32-bit instruction + encodings, as ratified in commit f88abf1 ("Integrating + load/store pair for RV32 with the main manual") of riscv-isa-manual. + + - const: zclsd + description: + The Zclsd extension implements the compressed (16-bit) version of the + Load/Store Pair for RV32. As with Zilsd, this extension was ratified + in commit f88abf1 ("Integrating load/store pair for RV32 with the + main manual") of riscv-isa-manual. + - const: zk description: The standard Zk Standard Scalar cryptography extension as ratified @@ -847,6 +861,16 @@ properties: anyOf: - const: v - const: zve32x + # Zclsd depends on Zilsd and Zca + - if: + contains: + anyOf: + - const: zclsd + then: + contains: + anyOf: + - const: zilsd + - const: zca
allOf: # Zcf extension does not exist on rv64 @@ -864,6 +888,21 @@ allOf: not: contains: const: zcf + # Zilsd extension does not exist on rv64 + - if: + properties: + riscv,isa-extensions: + contains: + const: zilsd + riscv,isa-base: + contains: + const: rv64i + then: + properties: + riscv,isa-extensions: + not: + contains: + const: zilsd
additionalProperties: true ...
On Thu, Aug 21, 2025 at 10:01:27PM +0800, Pincheng Wang wrote:
Add descriptions for the Zilsd (Load/Store pair instructions) and Zclsd (Compressed Load/Store pair instructions) ISA extensions which were ratified in commit f88abf1 ("Integrating load/store pair for RV32 with the main manual") of the riscv-isa-manual.
Signed-off-by: Pincheng Wang pincheng.plct@isrc.iscas.ac.cn
.../devicetree/bindings/riscv/extensions.yaml | 39 +++++++++++++++++++ 1 file changed, 39 insertions(+)
diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml index ede6a58ccf53..d72ffe8f6fa7 100644 --- a/Documentation/devicetree/bindings/riscv/extensions.yaml +++ b/Documentation/devicetree/bindings/riscv/extensions.yaml @@ -366,6 +366,20 @@ properties: guarantee on LR/SC sequences, as ratified in commit b1d806605f87 ("Updated to ratified state.") of the riscv profiles specification.
- const: zilsddescription:The standard Zilsd extension which provides support for alignedregister-pair load and store operations in 32-bit instructionencodings, as ratified in commit f88abf1 ("Integratingload/store pair for RV32 with the main manual") of riscv-isa-manual.- const: zclsddescription:The Zclsd extension implements the compressed (16-bit) version of theLoad/Store Pair for RV32. As with Zilsd, this extension was ratifiedin commit f88abf1 ("Integrating load/store pair for RV32 with themain manual") of riscv-isa-manual.- const: zk description: The standard Zk Standard Scalar cryptography extension as ratified@@ -847,6 +861,16 @@ properties: anyOf: - const: v - const: zve32x
# Zclsd depends on Zilsd and Zca- if:contains:anyOf:- const: zclsdthen:contains:anyOf:- const: zilsd- const: zcaallOf: # Zcf extension does not exist on rv64 @@ -864,6 +888,21 @@ allOf: not: contains: const: zcf
- # Zilsd extension does not exist on rv64
- if:
properties:
riscv,isa-extensions:contains:const: zilsd
This syntax is odd, it shouldn't be required to have zilsd in here and in the then. Did you copy this from Zcf or come up with it yourself because it didn't work otherwise?
riscv,isa-base:contains:const: rv64i- then:
properties:riscv,isa-extensions:not:contains:const: zilsdadditionalProperties: true ... -- 2.39.5
Add parsing for Zilsd and Zclsd ISA extensions which were ratified in commit f88abf1 ("Integrating load/store pair for RV32 with the main manual") of the riscv-isa-manual.
Signed-off-by: Pincheng Wang pincheng.plct@isrc.iscas.ac.cn --- arch/riscv/include/asm/hwcap.h | 2 ++ arch/riscv/kernel/cpufeature.c | 24 ++++++++++++++++++++++++ 2 files changed, 26 insertions(+)
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h index affd63e11b0a..7ad43d12c49f 100644 --- a/arch/riscv/include/asm/hwcap.h +++ b/arch/riscv/include/asm/hwcap.h @@ -106,6 +106,8 @@ #define RISCV_ISA_EXT_ZAAMO 97 #define RISCV_ISA_EXT_ZALRSC 98 #define RISCV_ISA_EXT_ZICBOP 99 +#define RISCV_ISA_EXT_ZILSD 100 +#define RISCV_ISA_EXT_ZCLSD 101
#define RISCV_ISA_EXT_XLINUXENVCFG 127
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index 743d53415572..8e7757db3895 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -242,6 +242,28 @@ static int riscv_ext_zcf_validate(const struct riscv_isa_ext_data *data, return -EPROBE_DEFER; }
+static int riscv_ext_zilsd_validate(const struct riscv_isa_ext_data *data, + const unsigned long *isa_bitmap) +{ + if (IS_ENABLED(CONFIG_64BIT)) + return -EINVAL; + + return 0; +} + +static int riscv_ext_zclsd_validate(const struct riscv_isa_ext_data *data, + const unsigned long *isa_bitmap) +{ + if (IS_ENABLED(CONFIG_64BIT)) + return -EINVAL; + + if (__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZILSD) && + __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZCA)) + return 0; + + return -EPROBE_DEFER; +} + static int riscv_vector_f_validate(const struct riscv_isa_ext_data *data, const unsigned long *isa_bitmap) { @@ -483,6 +505,8 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = { __RISCV_ISA_EXT_DATA_VALIDATE(zcd, RISCV_ISA_EXT_ZCD, riscv_ext_zcd_validate), __RISCV_ISA_EXT_DATA_VALIDATE(zcf, RISCV_ISA_EXT_ZCF, riscv_ext_zcf_validate), __RISCV_ISA_EXT_DATA_VALIDATE(zcmop, RISCV_ISA_EXT_ZCMOP, riscv_ext_zca_depends), + __RISCV_ISA_EXT_DATA_VALIDATE(zclsd, RISCV_ISA_EXT_ZCLSD, riscv_ext_zclsd_validate), + __RISCV_ISA_EXT_DATA_VALIDATE(zilsd, RISCV_ISA_EXT_ZILSD, riscv_ext_zilsd_validate), __RISCV_ISA_EXT_DATA(zba, RISCV_ISA_EXT_ZBA), __RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB), __RISCV_ISA_EXT_DATA(zbc, RISCV_ISA_EXT_ZBC),
Export Zilsd and Zclsd ISA extensions through hwprobe.
Signed-off-by: Pincheng Wang pincheng.plct@isrc.iscas.ac.cn --- Documentation/arch/riscv/hwprobe.rst | 8 ++++++++ arch/riscv/include/uapi/asm/hwprobe.h | 2 ++ arch/riscv/kernel/sys_hwprobe.c | 2 ++ 3 files changed, 12 insertions(+)
diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst index 2aa9be272d5d..538ab6c08f7b 100644 --- a/Documentation/arch/riscv/hwprobe.rst +++ b/Documentation/arch/riscv/hwprobe.rst @@ -275,6 +275,14 @@ The following keys are defined: ratified in commit 49f49c842ff9 ("Update to Rafified state") of riscv-zabha.
+ * :c:macro:`RISCV_HWPROBE_EXT_ZILSD`: The Zilsd extension is supported as + defined in the RISC-V ISA manual starting from commit f88abf1("Integrating + load/store pair for RV32 with the main manual") of the riscv-isa-manual. + + * :c:macro:`RISCV_HWPROBE_EXT_ZCLSD`: The Zclsd extension is supported as + defined in the RISC-V ISA manual starting from commit f88abf1("Integrating + load/store pair for RV32 with the main manual") of the riscv-isa-manual. + * :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: Deprecated. Returns similar values to :c:macro:`RISCV_HWPROBE_KEY_MISALIGNED_SCALAR_PERF`, but the key was mistakenly classified as a bitmask rather than a value. diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h index aaf6ad970499..e086179bb4fa 100644 --- a/arch/riscv/include/uapi/asm/hwprobe.h +++ b/arch/riscv/include/uapi/asm/hwprobe.h @@ -82,6 +82,8 @@ struct riscv_hwprobe { #define RISCV_HWPROBE_EXT_ZAAMO (1ULL << 56) #define RISCV_HWPROBE_EXT_ZALRSC (1ULL << 57) #define RISCV_HWPROBE_EXT_ZABHA (1ULL << 58) +#define RISCV_HWPROBE_EXT_ZILSD (1ULL << 59) +#define RISCV_HWPROBE_EXT_ZCLSD (1ULL << 60) #define RISCV_HWPROBE_KEY_CPUPERF_0 5 #define RISCV_HWPROBE_MISALIGNED_UNKNOWN (0 << 0) #define RISCV_HWPROBE_MISALIGNED_EMULATED (1 << 0) diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c index 0b170e18a2be..12f4b68ad2ac 100644 --- a/arch/riscv/kernel/sys_hwprobe.c +++ b/arch/riscv/kernel/sys_hwprobe.c @@ -111,6 +111,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair, EXT_KEY(ZCA); EXT_KEY(ZCB); EXT_KEY(ZCMOP); + EXT_KEY(ZCLSD); EXT_KEY(ZICBOM); EXT_KEY(ZICBOZ); EXT_KEY(ZICNTR); @@ -119,6 +120,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair, EXT_KEY(ZIHINTPAUSE); EXT_KEY(ZIHPM); EXT_KEY(ZIMOP); + EXT_KEY(ZILSD); EXT_KEY(ZKND); EXT_KEY(ZKNE); EXT_KEY(ZKNH);
Extend the KVM ISA extension ONE_REG interface to allow KVM user space to detect and enable Zilsd and Zclsd extensions for Guest/VM.
Signed-off-by: Pincheng Wang pincheng.plct@isrc.iscas.ac.cn --- arch/riscv/include/uapi/asm/kvm.h | 2 ++ arch/riscv/kvm/vcpu_onereg.c | 2 ++ 2 files changed, 4 insertions(+)
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h index 5f59fd226cc5..beb7ce06dce8 100644 --- a/arch/riscv/include/uapi/asm/kvm.h +++ b/arch/riscv/include/uapi/asm/kvm.h @@ -174,6 +174,8 @@ enum KVM_RISCV_ISA_EXT_ID { KVM_RISCV_ISA_EXT_ZCD, KVM_RISCV_ISA_EXT_ZCF, KVM_RISCV_ISA_EXT_ZCMOP, + KVM_RISCV_ISA_EXT_ZCLSD, + KVM_RISCV_ISA_EXT_ZILSD, KVM_RISCV_ISA_EXT_ZAWRS, KVM_RISCV_ISA_EXT_SMNPM, KVM_RISCV_ISA_EXT_SSNPM, diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c index 2e1b646f0d61..8219769fc4a1 100644 --- a/arch/riscv/kvm/vcpu_onereg.c +++ b/arch/riscv/kvm/vcpu_onereg.c @@ -64,6 +64,7 @@ static const unsigned long kvm_isa_ext_arr[] = { KVM_ISA_EXT_ARR(ZCD), KVM_ISA_EXT_ARR(ZCF), KVM_ISA_EXT_ARR(ZCMOP), + KVM_ISA_EXT_ARR(ZCLSD), KVM_ISA_EXT_ARR(ZFA), KVM_ISA_EXT_ARR(ZFH), KVM_ISA_EXT_ARR(ZFHMIN), @@ -78,6 +79,7 @@ static const unsigned long kvm_isa_ext_arr[] = { KVM_ISA_EXT_ARR(ZIHINTPAUSE), KVM_ISA_EXT_ARR(ZIHPM), KVM_ISA_EXT_ARR(ZIMOP), + KVM_ISA_EXT_ARR(ZILSD), KVM_ISA_EXT_ARR(ZKND), KVM_ISA_EXT_ARR(ZKNE), KVM_ISA_EXT_ARR(ZKNH),
The KVM RISC-V allows Zilsd and Zclsd extensions for Guest/VM so add this extension to get-reg-list test.
Signed-off-by: Pincheng Wang pincheng.plct@isrc.iscas.ac.cn --- tools/testing/selftests/kvm/riscv/get-reg-list.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/tools/testing/selftests/kvm/riscv/get-reg-list.c b/tools/testing/selftests/kvm/riscv/get-reg-list.c index a0b7dabb5040..477bd386265f 100644 --- a/tools/testing/selftests/kvm/riscv/get-reg-list.c +++ b/tools/testing/selftests/kvm/riscv/get-reg-list.c @@ -78,7 +78,9 @@ bool filter_reg(__u64 reg) case KVM_REG_RISCV_ISA_EXT | KVM_REG_RISCV_ISA_SINGLE | KVM_RISCV_ISA_EXT_ZCB: case KVM_REG_RISCV_ISA_EXT | KVM_REG_RISCV_ISA_SINGLE | KVM_RISCV_ISA_EXT_ZCD: case KVM_REG_RISCV_ISA_EXT | KVM_REG_RISCV_ISA_SINGLE | KVM_RISCV_ISA_EXT_ZCF: + case KVM_REG_RISCV_ISA_EXT | KVM_REG_RISCV_ISA_SINGLE | KVM_RISCV_ISA_EXT_ZCLSD: case KVM_REG_RISCV_ISA_EXT | KVM_REG_RISCV_ISA_SINGLE | KVM_RISCV_ISA_EXT_ZCMOP: + case KVM_REG_RISCV_ISA_EXT | KVM_REG_RISCV_ISA_SINGLE | KVM_RISCV_ISA_EXT_ZILSD: case KVM_REG_RISCV_ISA_EXT | KVM_REG_RISCV_ISA_SINGLE | KVM_RISCV_ISA_EXT_ZFA: case KVM_REG_RISCV_ISA_EXT | KVM_REG_RISCV_ISA_SINGLE | KVM_RISCV_ISA_EXT_ZFH: case KVM_REG_RISCV_ISA_EXT | KVM_REG_RISCV_ISA_SINGLE | KVM_RISCV_ISA_EXT_ZFHMIN: @@ -530,7 +532,9 @@ static const char *isa_ext_single_id_to_str(__u64 reg_off) KVM_ISA_EXT_ARR(ZCB), KVM_ISA_EXT_ARR(ZCD), KVM_ISA_EXT_ARR(ZCF), + KVM_ISA_EXT_ARR(ZCLSD), KVM_ISA_EXT_ARR(ZCMOP), + KVM_ISA_EXT_ARR(ZILSD), KVM_ISA_EXT_ARR(ZFA), KVM_ISA_EXT_ARR(ZFH), KVM_ISA_EXT_ARR(ZFHMIN), @@ -1199,7 +1203,9 @@ struct vcpu_reg_list *vcpu_configs[] = { &config_zcb, &config_zcd, &config_zcf, + &config_zclsd, &config_zcmop, + &config_zilsd, &config_zfa, &config_zfh, &config_zfhmin,
linux-kselftest-mirror@lists.linaro.org
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Conor Dooley -
Pincheng Wang