From 323925ed6dbb0ed877047b28fae4152527cc63db Mon Sep 17 00:00:00 2001 From: Andrew Jones Date: Wed, 20 Dec 2023 17:00:14 +0100 Subject: [PATCH] RISC-V: paravirt: Add skeleton for pv-time support Add the files and functions needed to support paravirt time on RISC-V. Also include the common code needed for the first application of pv-time, which is steal-time. In the next patches we'll complete the functions to fully enable steal-time support. Acked-by: Palmer Dabbelt Reviewed-by: Anup Patel Reviewed-by: Atish Patra Signed-off-by: Andrew Jones Signed-off-by: Anup Patel --- .../admin-guide/kernel-parameters.txt | 6 +- arch/riscv/include/asm/paravirt.h | 28 +++++++ arch/riscv/include/asm/paravirt_api_clock.h | 1 + arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/paravirt.c | 79 +++++++++++++++++++ arch/riscv/kernel/time.c | 3 + 6 files changed, 115 insertions(+), 3 deletions(-) create mode 100644 arch/riscv/include/asm/paravirt.h create mode 100644 arch/riscv/include/asm/paravirt_api_clock.h create mode 100644 arch/riscv/kernel/paravirt.c diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 65731b060e3f..a0d9259e4857 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3985,9 +3985,9 @@ vulnerability. System may allow data leaks with this option. - no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES] Disable paravirtualized - steal time accounting. steal time is computed, but - won't influence scheduler behaviour + no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES,RISCV] Disable + paravirtualized steal time accounting. steal time is + computed, but won't influence scheduler behaviour nosync [HW,M68K] Disables sync negotiation for all devices. diff --git a/arch/riscv/include/asm/paravirt.h b/arch/riscv/include/asm/paravirt.h new file mode 100644 index 000000000000..c0abde70fc2c --- /dev/null +++ b/arch/riscv/include/asm/paravirt.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_RISCV_PARAVIRT_H +#define _ASM_RISCV_PARAVIRT_H + +#ifdef CONFIG_PARAVIRT +#include + +struct static_key; +extern struct static_key paravirt_steal_enabled; +extern struct static_key paravirt_steal_rq_enabled; + +u64 dummy_steal_clock(int cpu); + +DECLARE_STATIC_CALL(pv_steal_clock, dummy_steal_clock); + +static inline u64 paravirt_steal_clock(int cpu) +{ + return static_call(pv_steal_clock)(cpu); +} + +int __init pv_time_init(void); + +#else + +#define pv_time_init() do {} while (0) + +#endif /* CONFIG_PARAVIRT */ +#endif /* _ASM_RISCV_PARAVIRT_H */ diff --git a/arch/riscv/include/asm/paravirt_api_clock.h b/arch/riscv/include/asm/paravirt_api_clock.h new file mode 100644 index 000000000000..65ac7cee0dad --- /dev/null +++ b/arch/riscv/include/asm/paravirt_api_clock.h @@ -0,0 +1 @@ +#include diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index fee22a3d1b53..807c2bde1f83 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -85,6 +85,7 @@ obj-$(CONFIG_SMP) += sbi-ipi.o obj-$(CONFIG_SMP) += cpu_ops_sbi.o endif obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o +obj-$(CONFIG_PARAVIRT) += paravirt.o obj-$(CONFIG_KGDB) += kgdb.o obj-$(CONFIG_KEXEC_CORE) += kexec_relocate.o crash_save_regs.o machine_kexec.o obj-$(CONFIG_KEXEC_FILE) += elf_kexec.o machine_kexec_file.o diff --git a/arch/riscv/kernel/paravirt.c b/arch/riscv/kernel/paravirt.c new file mode 100644 index 000000000000..48d802df7739 --- /dev/null +++ b/arch/riscv/kernel/paravirt.c @@ -0,0 +1,79 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2023 Ventana Micro Systems Inc. + */ + +#define pr_fmt(fmt) "riscv-pv: " fmt + +#include +#include +#include +#include +#include +#include + +#include + +struct static_key paravirt_steal_enabled; +struct static_key paravirt_steal_rq_enabled; + +static u64 native_steal_clock(int cpu) +{ + return 0; +} + +DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock); + +static bool steal_acc = true; +static int __init parse_no_stealacc(char *arg) +{ + steal_acc = false; + return 0; +} + +early_param("no-steal-acc", parse_no_stealacc); + +static bool __init has_pv_steal_clock(void) +{ + return false; +} + +static int pv_time_cpu_online(unsigned int cpu) +{ + return 0; +} + +static int pv_time_cpu_down_prepare(unsigned int cpu) +{ + return 0; +} + +static u64 pv_time_steal_clock(int cpu) +{ + return 0; +} + +int __init pv_time_init(void) +{ + int ret; + + if (!has_pv_steal_clock()) + return 0; + + ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, + "riscv/pv_time:online", + pv_time_cpu_online, + pv_time_cpu_down_prepare); + if (ret < 0) + return ret; + + static_call_update(pv_steal_clock, pv_time_steal_clock); + + static_key_slow_inc(¶virt_steal_enabled); + if (steal_acc) + static_key_slow_inc(¶virt_steal_rq_enabled); + + pr_info("Computing paravirt steal-time\n"); + + return 0; +} diff --git a/arch/riscv/kernel/time.c b/arch/riscv/kernel/time.c index 23641e82a9df..ba3477197789 100644 --- a/arch/riscv/kernel/time.c +++ b/arch/riscv/kernel/time.c @@ -12,6 +12,7 @@ #include #include #include +#include unsigned long riscv_timebase __ro_after_init; EXPORT_SYMBOL_GPL(riscv_timebase); @@ -45,4 +46,6 @@ void __init time_init(void) timer_probe(); tick_setup_hrtimer_broadcast(); + + pv_time_init(); }