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Sun, 26 Jul 2026 11:35:28 -0400 X-MC-Unique: h0TNje-SN9aIs_6A2pnzgw-1 X-Mimecast-MFC-AGG-ID: h0TNje-SN9aIs_6A2pnzgw_1785080126 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6D1FF180047F; Sun, 26 Jul 2026 15:35:26 +0000 (UTC) Received: from laptop.redhat.com (unknown [10.44.32.63]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id DA5EB180025F; Sun, 26 Jul 2026 15:35:17 +0000 (UTC) From: Eric Auger To: eric.auger.pro@gmail.com, eric.auger@redhat.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org, kvmarm@lists.linux.dev, peter.maydell@linaro.org, shaju.abraham@nutanix.com, khushit.shah@nutanix.com, yangjinqian1@huawei.com, cohuck@redhat.com, richard.henderson@linaro.org, sebott@redhat.com, skolothumtho@nvidia.com, philmd@oss.qualcomm.com Cc: maz@kernel.org, oliver.upton@linux.dev, pbonzini@redhat.com, armbru@redhat.com, berrange@redhat.com, abologna@redhat.com, jdenemar@redhat.com Subject: [RFC PATCH v7 17/18] target/arm/kvm: add utility to write idregs in scratch vcpu Date: Sun, 26 Jul 2026 17:29:55 +0200 Message-ID: <20260726153221.24773-18-eric.auger@redhat.com> In-Reply-To: <20260726153221.24773-1-eric.auger@redhat.com> References: <20260726153221.24773-1-eric.auger@redhat.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-MFC-PROC-ID: FD98-yWkOCprbnCExosyllGZcocZz7N-2z669NEb_Oo_1785080126 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true Signed-off-by: Eric Auger --- target/arm/kvm_arm.h | 3 +++ target/arm/kvm-stub.c | 6 +++++ target/arm/kvm.c | 51 +++++++++++++++++++++++++++++++++++++++++ target/arm/trace-events | 1 + 4 files changed, 61 insertions(+) diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h index 2b3474cc36..68e0597ac6 100644 --- a/target/arm/kvm_arm.h +++ b/target/arm/kvm_arm.h @@ -250,4 +250,7 @@ void arm_gic_cap_kvm_probe(GICCapability *v2, GICCapability *v3); */ char *kvm_print_register_name(uint64_t regidx); +bool kvm_idreg_write_scratch_vcpu(int cpufd, Visitor *v, const char *name, + void *opaque, Error **errp); + #endif diff --git a/target/arm/kvm-stub.c b/target/arm/kvm-stub.c index 88cbe8d85c..264938d2c5 100644 --- a/target/arm/kvm-stub.c +++ b/target/arm/kvm-stub.c @@ -119,3 +119,9 @@ char *kvm_print_register_name(uint64_t regidx) { g_assert_not_reached(); } + +bool kvm_idreg_write_scratch_vcpu(int cpufd, Visitor *v, const char *name, + void *opaque, Error **errp) +{ + g_assert_not_reached(); +} diff --git a/target/arm/kvm.c b/target/arm/kvm.c index fceffee262..e95c6e14ec 100644 --- a/target/arm/kvm.c +++ b/target/arm/kvm.c @@ -340,6 +340,57 @@ static ARM64SysRegField *get_field(int i, ARM64SysReg *reg) return NULL; } +bool kvm_idreg_write_scratch_vcpu(int cpufd, Visitor *v, const char *name, + void *opaque, Error **errp) +{ + ARM64SysRegField *field = (ARM64SysRegField *)opaque; + uint64_t mask, old_reg_val, new_reg_val, oldfv, newfv; + struct kvm_one_reg reg; + int lower = field->shift; + int length = field->length; + int index = field->index; + uint64_t kidx; + int ret; + + mask = MAKE_64BIT_MASK(lower, length); + + if (!visit_type_uint64(v, name, &newfv, errp)) { + return false; + } + + kidx = idregs_sysreg_to_kvm_reg(id_register_sysreg[index]); + ret = read_sys_reg64(cpufd, &old_reg_val, kidx); + if (ret) { + error_setg(errp, "failed to read the scratch vcpu value for field %s %m", + field->name); + return false; + } + oldfv = (old_reg_val & mask) >> lower; + + new_reg_val = old_reg_val & ~mask; + new_reg_val |= newfv << lower; + + reg.id = kidx; + reg.addr = (uintptr_t)&new_reg_val; + ret = ioctl(cpufd, KVM_SET_ONE_REG, ®); + if (ret) { + error_setg(errp, "failed to apply new value 0x%"PRIx64" for field %s " + "(previous is 0x%"PRIx64"): %m", newfv, field->name, oldfv); + return false; + } else { + uint64_t check_val, actualfv; + + ret = read_sys_reg64(cpufd, &check_val, kidx); + if (ret) { + error_setg(errp, "failed to read the new reg value: %m"); + return false; + } + actualfv = (check_val & mask) >> lower; + trace_kvm_idreg_write_scratch_vcpu(field->name, oldfv, newfv, actualfv); + } + return true; +} + static void set_sysreg_prop(Object *obj, Visitor *v, const char *name, void *opaque, Error **errp) diff --git a/target/arm/trace-events b/target/arm/trace-events index e67730de6b..71a2f5770c 100644 --- a/target/arm/trace-events +++ b/target/arm/trace-events @@ -20,6 +20,7 @@ get_sysreg_prop(const char *name, uint64_t value) "%s 0x%"PRIx64 set_sysreg_prop(const char *name, uint64_t old, uint64_t mask, uint64_t field_value, uint64_t new) "%s old reg value=0x%"PRIx64" mask=0x%"PRIx64" new field value=0x%"PRIx64" new reg value=0x%"PRIx64 nb_sysreg_props(const char *name, int count) "%s: %d SYSREG properties" unexpected_writable_reserved_field(const char *reg_name, const char *field_name, int lower, int upper) "Unexpected writable reserved field: %s.%s [%d,%d], skip it ..." +kvm_idreg_write_scratch_vcpu(const char *name, uint64_t oldfv, uint64_t newfv, uint64_t actualfv) "successful dry-run for %s old=0x%"PRIx64" new=0x%"PRIx64" actual=0x%"PRIx64 # cpu.c arm_cpu_reset(uint64_t mp_aff) "cpu %" PRIu64 -- 2.53.0