From nobody Sat Sep 26 20:03:11 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1789956191635778.6470537841384; Sun, 20 Sep 2026 19:03:11 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1x8TMN-00040u-Fl; Sun, 20 Sep 2026 22:02:23 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x8TML-00040b-CJ for qemu-devel@nongnu.org; Sun, 20 Sep 2026 22:02:21 -0400 Received: from mail.loongson.cn ([114.242.206.163]) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1x8TMI-0007a7-OP for qemu-devel@nongnu.org; Sun, 20 Sep 2026 22:02:21 -0400 Received: from loongson.cn (unknown [10.40.46.54]) by gateway (Coremail) with SMTP id _____8CxQNEkkLBqWgsOAA--.41380S3; Mon, 21 Sep 2026 10:02:12 +0800 (CST) Received: from fedora.loongson.cn (unknown [10.40.46.54]) by front1 (Coremail) with SMTP id qMiowJAxlMwikLBqhisjAA--.47516S2; Mon, 21 Sep 2026 10:02:10 +0800 (CST) From: Bibo Mao To: Song Gao <17746591750@163.com> Cc: Xianglai Li , qemu-devel@nongnu.org Subject: [PATCH] target/loongarch: Add paravirt preempt feature Date: Mon, 21 Sep 2026 10:03:33 +0800 Message-ID: <20260921020333.570784-1-maobibo@loongson.cn> X-Mailer: git-send-email 2.54.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: qMiowJAxlMwikLBqhisjAA--.47516S2 X-CM-SenderInfo: xpdruxter6z05rqj20fqof0/ X-Coremail-Antispam: 1Uk129KBj93XoWxAry3CF13Zr1kCw1xuw1fKrX_yoWrJFyrpF W7ArWSkrWUGwsakanxJ3Z5urn8GF4xGr4xXa43Ar4rAa1UGFWUZryIyF95KF1DX348XFyS qFn5Zr4q9F4fJabCm3ZEXasCq-sJn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUkjb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r106r15M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Jr0_JF4l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8JVWxJwA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_ Gr0_Gr1UM2AIxVAIcxkEcVAq07x20xvEncxIr21l57IF6xkI12xvs2x26I8E6xACxx1l5I 8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AK xVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41l42xK82IYc2Ij64 vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8G jcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1Y6r17MIIYrxkI7VAKI48JMIIF0xvE2I x0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0xvE42xK 8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I 0E14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf9x07j8yCJUUUUU= 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=114.242.206.163; envelope-from=maobibo@loongson.cn; helo=mail.loongson.cn X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, 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-ZM-MESSAGEID: 1789956196771158500 Content-Type: text/plain; charset="utf-8" Paravirt preempt feature is OnOffAuto type, it is disabled by default, also the feature detection is added to check whether it is supported on KVM host. Signed-off-by: Bibo Mao --- target/loongarch/cpu.h | 2 ++ target/loongarch/kvm/kvm.c | 39 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/target/loongarch/cpu.h b/target/loongarch/cpu.h index c592f69885..c6dad2417c 100644 --- a/target/loongarch/cpu.h +++ b/target/loongarch/cpu.h @@ -302,6 +302,7 @@ enum loongarch_features { LOONGARCH_FEATURE_STEALTIME, LOONGARCH_FEATURE_PTW, LOONGARCH_FEATURE_MSGINT, + LOONGARCH_FEATURE_PV_PREEMPT, }; =20 typedef struct LoongArchBT { @@ -464,6 +465,7 @@ struct ArchCPU { OnOffAuto msgint; OnOffAuto kvm_pv_ipi; OnOffAuto kvm_steal_time; + OnOffAuto kvm_pv_preempt; int32_t socket_id; /* socket-id of this CPU */ int32_t core_id; /* core-id of this CPU */ int32_t thread_id; /* thread-id of this CPU */ diff --git a/target/loongarch/kvm/kvm.c b/target/loongarch/kvm/kvm.c index 941142305e..7ca95181a1 100644 --- a/target/loongarch/kvm/kvm.c +++ b/target/loongarch/kvm/kvm.c @@ -1039,6 +1039,12 @@ static bool kvm_feature_supported(CPUState *cs, enum= loongarch_features feature) ret =3D kvm_vm_ioctl(kvm_state, KVM_HAS_DEVICE_ATTR, &attr); return (ret =3D=3D 0); =20 + case LOONGARCH_FEATURE_PV_PREEMPT: + attr.group =3D KVM_LOONGARCH_VM_FEAT_CTRL; + attr.attr =3D KVM_LOONGARCH_VM_FEAT_PV_PREEMPT, + ret =3D kvm_vm_ioctl(kvm_state, KVM_HAS_DEVICE_ATTR, &attr); + return (ret =3D=3D 0); + default: return false; } @@ -1203,6 +1209,21 @@ static int kvm_cpu_check_pv_features(CPUState *cs, E= rror **errp) env->pv_features |=3D BIT(KVM_FEATURE_STEAL_TIME); } =20 + kvm_supported =3D kvm_feature_supported(cs, LOONGARCH_FEATURE_PV_PREEM= PT); + if (cpu->kvm_pv_preempt =3D=3D ON_OFF_AUTO_ON) { + if (!kvm_supported) { + error_setg(errp, "'pv preempt' feature not supported by KVM ho= st"); + return -ENOTSUP; + } + } else if (cpu->kvm_pv_preempt !=3D ON_OFF_AUTO_AUTO) { + kvm_supported =3D false; + } + + /* Feature preempt_hint depends on steal_time */ + if (kvm_supported && (cpu->kvm_pv_preempt =3D=3D ON_OFF_AUTO_ON)) { + env->pv_features |=3D BIT(KVM_FEATURE_PREEMPT); + } + if (object_dynamic_cast(OBJECT(ms), TYPE_LOONGARCH_VIRT_MACHINE)) { LoongArchVirtMachineState *lvms =3D LOONGARCH_VIRT_MACHINE(ms); =20 @@ -1412,6 +1433,18 @@ static void kvm_steal_time_set(Object *obj, bool val= ue, Error **errp) cpu->kvm_steal_time =3D value ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF; } =20 +static bool kvm_pv_preempt_get(Object *obj, Error **errp) +{ + return LOONGARCH_CPU(obj)->kvm_pv_preempt !=3D ON_OFF_AUTO_OFF; +} + +static void kvm_pv_preempt_set(Object *obj, bool value, Error **errp) +{ + LoongArchCPU *cpu =3D LOONGARCH_CPU(obj); + + cpu->kvm_pv_preempt =3D value ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF; +} + void kvm_loongarch_cpu_post_init(LoongArchCPU *cpu) { cpu->lbt =3D ON_OFF_AUTO_AUTO; @@ -1437,6 +1470,12 @@ void kvm_loongarch_cpu_post_init(LoongArchCPU *cpu) kvm_steal_time_set); object_property_set_description(OBJECT(cpu), "kvm-steal-time", "Set off to disable KVM steal time."); + + cpu->kvm_pv_preempt =3D ON_OFF_AUTO_OFF; + object_property_add_bool(OBJECT(cpu), "kvm-pv-preempt", kvm_pv_preempt= _get, + kvm_pv_preempt_set); + object_property_set_description(OBJECT(cpu), "kvm-pv-preempt", + "Set off to disable KVM paravirt preem= pt."); } =20 int kvm_arch_destroy_vcpu(CPUState *cs) base-commit: c1c18d1e640b64292859ce9f30f3c344edfb0294 --=20 2.54.0