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Tue, 28 Jul 2026 20:22:27 -0700 (PDT) From: Zephyr Li To: qemu-devel@nongnu.org Cc: qemu-riscv@nongnu.org, palmer@dabbelt.com, alistair.francis@wdc.com, liwei1518@gmail.com, daniel.barboza@oss.qualcomm.com, zhiwei_liu@linux.alibaba.com, chao.liu@processmission.com, Zephyr Li Subject: [PATCH] target/riscv: do not count ECALL in minstret Date: Wed, 29 Jul 2026 11:22:02 +0800 Message-ID: <20260729032202.1415046-1-fritchleybohrer@gmail.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: pass client-ip=2607:f8b0:4864:39::3; envelope-from=fritchleybohrer@gmail.com; helo=mail-pj2-x03.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @gmail.com) X-ZM-MESSAGEID: 1785295410947158500 Content-Type: text/plain; charset="utf-8" With icount enabled, helper_raise_exception() leaves ECALL in icount_get_raw() because it exits without restoring the current TB state. This makes minstret count an instruction that does not retire. Adjust only the fixed minstret baseline so that mcycle accounting remains unchanged. Add an RV64 softmmu regression test for the issue. Resolves: https://gitlab.com/qemu-project/qemu/-/issues/4087 Signed-off-by: Zephyr Li Reviewed-by: Daniel Henrique Barboza --- target/riscv/tcg/op_helper.c | 6 +++ target/riscv/tcg/pmu.c | 44 +++++++++++++----- target/riscv/tcg/pmu.h | 1 + tests/tcg/riscv64/Makefile.softmmu-target | 4 ++ tests/tcg/riscv64/test-minstret-ecall.S | 55 +++++++++++++++++++++++ 5 files changed, 98 insertions(+), 12 deletions(-) create mode 100644 tests/tcg/riscv64/test-minstret-ecall.S diff --git a/target/riscv/tcg/op_helper.c b/target/riscv/tcg/op_helper.c index ba3c7da375..acdccd1a97 100644 --- a/target/riscv/tcg/op_helper.c +++ b/target/riscv/tcg/op_helper.c @@ -21,6 +21,9 @@ #include "qemu/osdep.h" #include "cpu.h" #include "target/riscv/tcg/csr.h" +#ifndef CONFIG_USER_ONLY +#include "pmu.h" +#endif #include "internals.h" #include "exec/cputlb.h" #include "accel/tcg/cpu-ldst.h" @@ -47,6 +50,9 @@ G_NORETURN void riscv_raise_exception(CPURISCVState *env, =20 void helper_raise_exception(CPURISCVState *env, uint32_t exception) { +#ifndef CONFIG_USER_ONLY + riscv_pmu_decr_instret(env); +#endif riscv_raise_exception(env, exception, 0); } =20 diff --git a/target/riscv/tcg/pmu.c b/target/riscv/tcg/pmu.c index 38ad2737e1..1a4658319b 100644 --- a/target/riscv/tcg/pmu.c +++ b/target/riscv/tcg/pmu.c @@ -49,6 +49,21 @@ static bool riscv_pmu_counter_enabled(RISCVCPU *cpu, uin= t32_t ctr_idx) } } =20 +static bool riscv_pmu_counter_filtered(CPURISCVState *env, uint64_t cfg) +{ + bool virt_on =3D env->virt_enabled; + + return (env->priv =3D=3D PRV_M && (cfg & MHPMEVENT_BIT_MINH)) || + (env->priv =3D=3D PRV_S && virt_on && + (cfg & MHPMEVENT_BIT_VSINH)) || + (env->priv =3D=3D PRV_U && virt_on && + (cfg & MHPMEVENT_BIT_VUINH)) || + (env->priv =3D=3D PRV_S && !virt_on && + (cfg & MHPMEVENT_BIT_SINH)) || + (env->priv =3D=3D PRV_U && !virt_on && + (cfg & MHPMEVENT_BIT_UINH)); +} + /* * Information needed to update counters: * new_priv, new_virt: To correctly save starting snapshot for the newly @@ -147,12 +162,27 @@ void riscv_pmu_update_fixed_ctrs(CPURISCVState *env, riscv_pmu_icount_update_priv(env, newpriv, new_virt); } =20 +void riscv_pmu_decr_instret(CPURISCVState *env) +{ + if (!icount_enabled() || + (env->mcountinhibit & COUNTEREN_IR) || + riscv_pmu_counter_filtered(env, env->minstretcfg)) { + return; + } + + /* + * minstret is derived from icount, which includes the current + * instruction. Move the baseline forward to exclude an instruction + * that raises an exception and therefore does not retire. + */ + env->pmu_ctrs[2].mhpmcounter_prev++; +} + int riscv_pmu_incr_ctr(RISCVCPU *cpu, enum riscv_pmu_event_idx event_idx) { uint32_t ctr_idx; CPURISCVState *env =3D &cpu->env; uint64_t max_val =3D UINT64_MAX; - bool virt_on =3D env->virt_enabled; PMUCTRState *counter; gpointer value; =20 @@ -170,17 +200,7 @@ int riscv_pmu_incr_ctr(RISCVCPU *cpu, enum riscv_pmu_e= vent_idx event_idx) return -1; } =20 - /* Privilege mode filtering */ - if ((env->priv =3D=3D PRV_M && - (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_MINH)) || - (env->priv =3D=3D PRV_S && virt_on && - (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_VSINH)) || - (env->priv =3D=3D PRV_U && virt_on && - (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_VUINH)) || - (env->priv =3D=3D PRV_S && !virt_on && - (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_SINH)) || - (env->priv =3D=3D PRV_U && !virt_on && - (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_UINH))) { + if (riscv_pmu_counter_filtered(env, env->mhpmevent_val[ctr_idx])) { return 0; } =20 diff --git a/target/riscv/tcg/pmu.h b/target/riscv/tcg/pmu.h index b4f1e469a2..2429c01b77 100644 --- a/target/riscv/tcg/pmu.h +++ b/target/riscv/tcg/pmu.h @@ -36,6 +36,7 @@ int riscv_pmu_setup_timer(CPURISCVState *env, uint64_t va= lue, uint32_t ctr_idx); void riscv_pmu_update_fixed_ctrs(CPURISCVState *env, privilege_mode_t newp= riv, bool new_virt); +void riscv_pmu_decr_instret(CPURISCVState *env); RISCVException riscv_pmu_read_ctr(CPURISCVState *env, target_ulong *val, bool upper_half, uint32_t ctr_idx); =20 diff --git a/tests/tcg/riscv64/Makefile.softmmu-target b/tests/tcg/riscv64/= Makefile.softmmu-target index 82be8a2c91..42038ce3b4 100644 --- a/tests/tcg/riscv64/Makefile.softmmu-target +++ b/tests/tcg/riscv64/Makefile.softmmu-target @@ -24,6 +24,10 @@ EXTRA_RUNS +=3D run-test-mepc-masking run-test-mepc-masking: test-mepc-masking $(call run-test, $<, $(QEMU) $(QEMU_OPTS)$<) =20 +EXTRA_RUNS +=3D run-test-minstret-ecall +run-test-minstret-ecall: test-minstret-ecall + $(call run-test, $<, $(QEMU) -icount shift=3D1 $(QEMU_OPTS)$<) + EXTRA_RUNS +=3D run-plugin-doubletrap run-plugin-doubletrap: doubletrap $(call run-test, $<, \ diff --git a/tests/tcg/riscv64/test-minstret-ecall.S b/tests/tcg/riscv64/te= st-minstret-ecall.S new file mode 100644 index 0000000000..ab268f7f22 --- /dev/null +++ b/tests/tcg/riscv64/test-minstret-ecall.S @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + + .option norvc + + .text + .global _start +_start: + lla t0, trap + csrw mtvec, t0 + + /* + * The first CSR read retires after obtaining s0. The ecall does not + * retire, so the trap handler must observe a difference of one. + */ + csrr s0, minstret + ecall + sub t0, s1, s0 + li t1, 1 + bne t0, t1, fail + + li a0, 0 + j _exit + +trap: + csrr s1, minstret + csrr t0, mcause + li t1, 11 /* Environment call from M-mode */ + bne t0, t1, fail + + csrr t0, mepc + addi t0, t0, 4 + csrw mepc, t0 + mret + +fail: + li a0, 1 + +_exit: + lla a1, semiargs + li t0, 0x20026 /* ADP_Stopped_ApplicationExit */ + sd t0, 0(a1) + sd a0, 8(a1) + li a0, 0x20 /* TARGET_SYS_EXIT_EXTENDED */ + + /* Semihosting call sequence */ + .balign 16 + slli zero, zero, 0x1f + ebreak + srai zero, zero, 0x7 + j . + + .data + .balign 16 +semiargs: + .space 16 --=20 2.43.0