From c695724868ce4049fd79c5a509880dbdf171e744 Mon Sep 17 00:00:00 2001 From: Anup Patel Date: Sun, 2 Feb 2020 19:12:16 +0530 Subject: [PATCH] target/riscv: Emulate TIME CSRs for privileged mode Currently, TIME CSRs are emulated only for user-only mode. This patch add TIME CSRs emulation for privileged mode. For privileged mode, the TIME CSRs will return value provided by rdtime callback which is registered by QEMU machine/platform emulation (i.e. CLINT emulation). If rdtime callback is not available then the monitor (i.e. OpenSBI) will trap-n-emulate TIME CSRs in software. We see 25+% performance improvement in hackbench numbers when TIME CSRs are not trap-n-emulated. Signed-off-by: Anup Patel Reviewed-by: Alistair Francis Signed-off-by: Palmer Dabbelt --- target/riscv/cpu.h | 5 +++ target/riscv/cpu_helper.c | 5 +++ target/riscv/csr.c | 86 ++++++++++++++++++++++++++++++++++++++++++++--- 3 files changed, 92 insertions(+), 4 deletions(-) diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h index d52f209361..3dcdf92227 100644 --- a/target/riscv/cpu.h +++ b/target/riscv/cpu.h @@ -159,6 +159,7 @@ struct CPURISCVState { target_ulong htval; target_ulong htinst; target_ulong hgatp; + uint64_t htimedelta; /* Virtual CSRs */ target_ulong vsstatus; @@ -201,6 +202,9 @@ struct CPURISCVState { /* physical memory protection */ pmp_table_t pmp_state; + /* machine specific rdtime callback */ + uint64_t (*rdtime_fn)(void); + /* True if in debugger mode. */ bool debugger; #endif @@ -322,6 +326,7 @@ void riscv_cpu_swap_hypervisor_regs(CPURISCVState *env); int riscv_cpu_claim_interrupts(RISCVCPU *cpu, uint32_t interrupts); uint32_t riscv_cpu_update_mip(RISCVCPU *cpu, uint32_t mask, uint32_t value); #define BOOL_TO_MASK(x) (-!!(x)) /* helper for riscv_cpu_update_mip value */ +void riscv_cpu_set_rdtime_fn(CPURISCVState *env, uint64_t (*fn)(void)); #endif void riscv_cpu_set_mode(CPURISCVState *env, target_ulong newpriv); diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c index 29a1b37d88..5ea5d133aa 100644 --- a/target/riscv/cpu_helper.c +++ b/target/riscv/cpu_helper.c @@ -258,6 +258,11 @@ uint32_t riscv_cpu_update_mip(RISCVCPU *cpu, uint32_t mask, uint32_t value) return old; } +void riscv_cpu_set_rdtime_fn(CPURISCVState *env, uint64_t (*fn)(void)) +{ + env->rdtime_fn = fn; +} + void riscv_cpu_set_mode(CPURISCVState *env, target_ulong newpriv) { if (newpriv > PRV_M) { diff --git a/target/riscv/csr.c b/target/riscv/csr.c index 572a478e8c..11d184cd16 100644 --- a/target/riscv/csr.c +++ b/target/riscv/csr.c @@ -238,6 +238,32 @@ static int read_timeh(CPURISCVState *env, int csrno, target_ulong *val) #else /* CONFIG_USER_ONLY */ +static int read_time(CPURISCVState *env, int csrno, target_ulong *val) +{ + uint64_t delta = riscv_cpu_virt_enabled(env) ? env->htimedelta : 0; + + if (!env->rdtime_fn) { + return -1; + } + + *val = env->rdtime_fn() + delta; + return 0; +} + +#if defined(TARGET_RISCV32) +static int read_timeh(CPURISCVState *env, int csrno, target_ulong *val) +{ + uint64_t delta = riscv_cpu_virt_enabled(env) ? env->htimedelta : 0; + + if (!env->rdtime_fn) { + return -1; + } + + *val = (env->rdtime_fn() + delta) >> 32; + return 0; +} +#endif + /* Machine constants */ #define M_MODE_INTERRUPTS (MIP_MSIP | MIP_MTIP | MIP_MEIP) @@ -930,6 +956,56 @@ static int write_hgatp(CPURISCVState *env, int csrno, target_ulong val) return 0; } +static int read_htimedelta(CPURISCVState *env, int csrno, target_ulong *val) +{ + if (!env->rdtime_fn) { + return -1; + } + +#if defined(TARGET_RISCV32) + *val = env->htimedelta & 0xffffffff; +#else + *val = env->htimedelta; +#endif + return 0; +} + +static int write_htimedelta(CPURISCVState *env, int csrno, target_ulong val) +{ + if (!env->rdtime_fn) { + return -1; + } + +#if defined(TARGET_RISCV32) + env->htimedelta = deposit64(env->htimedelta, 0, 32, (uint64_t)val); +#else + env->htimedelta = val; +#endif + return 0; +} + +#if defined(TARGET_RISCV32) +static int read_htimedeltah(CPURISCVState *env, int csrno, target_ulong *val) +{ + if (!env->rdtime_fn) { + return -1; + } + + *val = env->htimedelta >> 32; + return 0; +} + +static int write_htimedeltah(CPURISCVState *env, int csrno, target_ulong val) +{ + if (!env->rdtime_fn) { + return -1; + } + + env->htimedelta = deposit64(env->htimedelta, 32, 32, (uint64_t)val); + return 0; +} +#endif + /* Virtual CSR Registers */ static int read_vsstatus(CPURISCVState *env, int csrno, target_ulong *val) { @@ -1202,14 +1278,12 @@ static riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = { [CSR_INSTRETH] = { ctr, read_instreth }, #endif - /* User-level time CSRs are only available in linux-user - * In privileged mode, the monitor emulates these CSRs */ -#if defined(CONFIG_USER_ONLY) + /* In privileged mode, the monitor will have to emulate TIME CSRs only if + * rdtime callback is not provided by machine/platform emulation */ [CSR_TIME] = { ctr, read_time }, #if defined(TARGET_RISCV32) [CSR_TIMEH] = { ctr, read_timeh }, #endif -#endif #if !defined(CONFIG_USER_ONLY) /* Machine Timers and Counters */ @@ -1275,6 +1349,10 @@ static riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = { [CSR_HTVAL] = { hmode, read_htval, write_htval }, [CSR_HTINST] = { hmode, read_htinst, write_htinst }, [CSR_HGATP] = { hmode, read_hgatp, write_hgatp }, + [CSR_HTIMEDELTA] = { hmode, read_htimedelta, write_htimedelta }, +#if defined(TARGET_RISCV32) + [CSR_HTIMEDELTAH] = { hmode, read_htimedeltah, write_htimedeltah}, +#endif [CSR_VSSTATUS] = { hmode, read_vsstatus, write_vsstatus }, [CSR_VSIP] = { hmode, NULL, NULL, rmw_vsip }, -- 2.11.0