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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-18 18:50:03 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-18 18:50:03 +0000 |
commit | 01a69402cf9d38ff180345d55c2ee51c7e89fbc7 (patch) | |
tree | b406c5242a088c4f59c6e4b719b783f43aca6ae9 /arch/riscv/kernel/paravirt.c | |
parent | Adding upstream version 6.7.12. (diff) | |
download | linux-d6208063787d081e93f32d9942baa7f9358b45f1.tar.xz linux-d6208063787d081e93f32d9942baa7f9358b45f1.zip |
Adding upstream version 6.8.9.upstream/6.8.9
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/riscv/kernel/paravirt.c')
-rw-r--r-- | arch/riscv/kernel/paravirt.c | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/arch/riscv/kernel/paravirt.c b/arch/riscv/kernel/paravirt.c new file mode 100644 index 0000000000..0d6225fd31 --- /dev/null +++ b/arch/riscv/kernel/paravirt.c @@ -0,0 +1,135 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2023 Ventana Micro Systems Inc. + */ + +#define pr_fmt(fmt) "riscv-pv: " fmt + +#include <linux/cpuhotplug.h> +#include <linux/compiler.h> +#include <linux/errno.h> +#include <linux/init.h> +#include <linux/jump_label.h> +#include <linux/kconfig.h> +#include <linux/kernel.h> +#include <linux/percpu-defs.h> +#include <linux/printk.h> +#include <linux/static_call.h> +#include <linux/types.h> + +#include <asm/barrier.h> +#include <asm/page.h> +#include <asm/paravirt.h> +#include <asm/sbi.h> + +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 DEFINE_PER_CPU(struct sbi_sta_struct, steal_time) __aligned(64); + +static bool __init has_pv_steal_clock(void) +{ + if (sbi_spec_version >= sbi_mk_version(2, 0) && + sbi_probe_extension(SBI_EXT_STA) > 0) { + pr_info("SBI STA extension detected\n"); + return true; + } + + return false; +} + +static int sbi_sta_steal_time_set_shmem(unsigned long lo, unsigned long hi, + unsigned long flags) +{ + struct sbiret ret; + + ret = sbi_ecall(SBI_EXT_STA, SBI_EXT_STA_STEAL_TIME_SET_SHMEM, + lo, hi, flags, 0, 0, 0); + if (ret.error) { + if (lo == SBI_STA_SHMEM_DISABLE && hi == SBI_STA_SHMEM_DISABLE) + pr_warn("Failed to disable steal-time shmem"); + else + pr_warn("Failed to set steal-time shmem"); + return sbi_err_map_linux_errno(ret.error); + } + + return 0; +} + +static int pv_time_cpu_online(unsigned int cpu) +{ + struct sbi_sta_struct *st = this_cpu_ptr(&steal_time); + phys_addr_t pa = __pa(st); + unsigned long lo = (unsigned long)pa; + unsigned long hi = IS_ENABLED(CONFIG_32BIT) ? upper_32_bits((u64)pa) : 0; + + return sbi_sta_steal_time_set_shmem(lo, hi, 0); +} + +static int pv_time_cpu_down_prepare(unsigned int cpu) +{ + return sbi_sta_steal_time_set_shmem(SBI_STA_SHMEM_DISABLE, + SBI_STA_SHMEM_DISABLE, 0); +} + +static u64 pv_time_steal_clock(int cpu) +{ + struct sbi_sta_struct *st = per_cpu_ptr(&steal_time, cpu); + __le32 sequence; + __le64 steal; + + /* + * Check the sequence field before and after reading the steal + * field. Repeat the read if it is different or odd. + */ + do { + sequence = READ_ONCE(st->sequence); + virt_rmb(); + steal = READ_ONCE(st->steal); + virt_rmb(); + } while ((le32_to_cpu(sequence) & 1) || + sequence != READ_ONCE(st->sequence)); + + return le64_to_cpu(steal); +} + +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; +} |