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b=JYXou3GXG4cKitsmoVYyC87XDBzN5GnnFx3h3QchgTFzVG8SahLk3AAJ5NoajWA/9VZtVykUL3ch2ukF7BQ81OZhmqWu1KXCcVI4Qp5WnVe2+dE4gBHJ0Xn6JX6Cz4alz9q16cgOAqGg7GIWN3jw0NFxQr9HPJ8lhYJNXybcDNYWpMwkYep1w7Y2bTgqIfw8+v6cHUheLjRUegv/VT8MamQ5zns5hs7O4c4XEr2PlDB/e19ktecYs/6OvGNIkJ7qAQm/6kXXz/GWvhhfpfkvsYO1/nlRiKh2lm3h7A1nfqPIFv1BU+WzhKz+w9kw/yqTGhVVH8z9PqYbJOvK/jJmig== From: Mykyta Poturai To: "xen-devel@lists.xenproject.org" CC: Mykyta Poturai , Stefano Stabellini , Julien Grall , Bertrand Marquis , Michal Orzel , Volodymyr Babchuk Subject: [PATCH v8 1/6] arm/irq: Keep track of irq affinities Thread-Topic: [PATCH v8 1/6] arm/irq: Keep track of irq affinities Thread-Index: AQHc5GGlhAXHchguZ0CmpA+A7r8r9w== Date: Fri, 15 May 2026 11:54:55 +0000 Message-ID: <72c0423562c81fe1bc90aaaf1f79599a94e771ca.1778845596.git.mykyta_poturai@epam.com> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=epam.com; 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charset="utf-8" Currently on Arm the desc->affinity mask of an irq is never updated, which makes it hard to know the actual affinity of an interrupt. Fix this by updating the field in irq_set_affinity. Changing desc->affinity requires desc->lock to be held, so add an assertion to ensure that callers of irq_set_affinity are doing so correctly. With desc->lock now being required for irq_set_affinity, add locking around calls to it where it was missing. Signed-off-by: Mykyta Poturai Reviewed-by: Bertrand Marquis --- v6->v7: * update commit message * fix possible locking on null desc * collect RBs v5->v6: * add missing locking around irq_set_affinity calls v4->v5: * add locking v3->v4: * patch introduced --- xen/arch/arm/gic-vgic.c | 2 ++ xen/arch/arm/irq.c | 9 +++++++-- xen/arch/arm/vgic.c | 14 ++++++++++++-- xen/arch/arm/vgic/vgic-mmio-v2.c | 11 +++++------ xen/arch/arm/vgic/vgic.c | 21 +++++++++++++-------- 5 files changed, 39 insertions(+), 18 deletions(-) diff --git a/xen/arch/arm/gic-vgic.c b/xen/arch/arm/gic-vgic.c index fae80e6cd2..28ad4903b4 100644 --- a/xen/arch/arm/gic-vgic.c +++ b/xen/arch/arm/gic-vgic.c @@ -232,7 +232,9 @@ static void gic_update_one_lr(struct vcpu *v, int i) if ( test_bit(GIC_IRQ_GUEST_MIGRATING, &p->status) ) { struct vcpu *v_target =3D vgic_get_target_vcpu(v, irq); + spin_lock(&p->desc->lock); irq_set_affinity(p->desc, cpumask_of(v_target->processor)); + spin_unlock(&p->desc->lock); clear_bit(GIC_IRQ_GUEST_MIGRATING, &p->status); } } diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c index 73e58a5108..7204bc2b68 100644 --- a/xen/arch/arm/irq.c +++ b/xen/arch/arm/irq.c @@ -216,10 +216,15 @@ static inline struct domain *irq_get_domain(struct ir= q_desc *desc) return irq_get_guest_info(desc)->d; } =20 +/* Must be called with desc->lock held */ void irq_set_affinity(struct irq_desc *desc, const cpumask_t *mask) { - if ( desc !=3D NULL ) - desc->handler->set_affinity(desc, mask); + if ( desc =3D=3D NULL ) + return; + + ASSERT(spin_is_locked(&desc->lock)); + cpumask_copy(desc->affinity, mask); + desc->handler->set_affinity(desc, mask); } =20 int request_irq(unsigned int irq, unsigned int irqflags, diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c index 6647071ad4..c59f6873db 100644 --- a/xen/arch/arm/vgic.c +++ b/xen/arch/arm/vgic.c @@ -445,7 +445,9 @@ bool vgic_migrate_irq(struct vcpu *old, struct vcpu *ne= w, unsigned int irq) =20 if ( list_empty(&p->inflight) ) { + spin_lock(&p->desc->lock); irq_set_affinity(p->desc, cpumask_of(new->processor)); + spin_unlock(&p->desc->lock); spin_unlock_irqrestore(&old->arch.vgic.lock, flags); return true; } @@ -453,7 +455,9 @@ bool vgic_migrate_irq(struct vcpu *old, struct vcpu *ne= w, unsigned int irq) if ( !list_empty(&p->lr_queue) ) { vgic_remove_irq_from_queues(old, p); + spin_lock(&p->desc->lock); irq_set_affinity(p->desc, cpumask_of(new->processor)); + spin_unlock(&p->desc->lock); spin_unlock_irqrestore(&old->arch.vgic.lock, flags); vgic_inject_irq(new->domain, new, irq, true); return true; @@ -473,6 +477,7 @@ void arch_move_irqs(struct vcpu *v) struct domain *d =3D v->domain; struct pending_irq *p; struct vcpu *v_target; + unsigned long flags; int i; =20 /* @@ -494,7 +499,13 @@ void arch_move_irqs(struct vcpu *v) p =3D irq_to_pending(v_target, virq); =20 if ( v_target =3D=3D v && !test_bit(GIC_IRQ_GUEST_MIGRATING, &p->s= tatus) ) + { + if ( !p->desc ) + continue; + spin_lock_irqsave(&p->desc->lock, flags); irq_set_affinity(p->desc, cpu_mask); + spin_unlock_irqrestore(&p->desc->lock, flags); + } } } =20 @@ -574,8 +585,8 @@ void vgic_enable_irqs(struct vcpu *v, uint32_t r, unsig= ned int n) spin_unlock_irqrestore(&v_target->arch.vgic.lock, flags); if ( p->desc !=3D NULL ) { - irq_set_affinity(p->desc, cpumask_of(v_target->processor)); spin_lock_irqsave(&p->desc->lock, flags); + irq_set_affinity(p->desc, cpumask_of(v_target->processor)); /* * The irq cannot be a PPI, we only support delivery of SPIs * to guests. @@ -944,4 +955,3 @@ void vgic_check_inflight_irqs_pending(struct vcpu *v, u= nsigned int rank, uint32_ * indent-tabs-mode: nil * End: */ - diff --git a/xen/arch/arm/vgic/vgic-mmio-v2.c b/xen/arch/arm/vgic/vgic-mmio= -v2.c index b7c2d7ce99..fc04741ca1 100644 --- a/xen/arch/arm/vgic/vgic-mmio-v2.c +++ b/xen/arch/arm/vgic/vgic-mmio-v2.c @@ -159,24 +159,23 @@ static void vgic_mmio_write_target(struct vcpu *vcpu, for ( i =3D 0; i < len; i++ ) { struct vgic_irq *irq =3D vgic_get_irq(vcpu->domain, NULL, intid + = i); + struct irq_desc *desc =3D irq_to_desc(irq->hwintid); =20 - spin_lock_irqsave(&irq->irq_lock, flags); + spin_lock_irqsave(&desc->lock, flags); + spin_lock(&irq->irq_lock); =20 irq->targets =3D (val >> (i * 8)) & cpu_mask; if ( irq->targets ) { irq->target_vcpu =3D vcpu->domain->vcpu[ffs(irq->targets) - 1]; if ( irq->hw ) - { - struct irq_desc *desc =3D irq_to_desc(irq->hwintid); - irq_set_affinity(desc, cpumask_of(irq->target_vcpu->proces= sor)); - } } else irq->target_vcpu =3D NULL; =20 - spin_unlock_irqrestore(&irq->irq_lock, flags); + spin_unlock(&irq->irq_lock); + spin_unlock_irqrestore(&desc->lock, flags); vgic_put_irq(vcpu->domain, irq); } } diff --git a/xen/arch/arm/vgic/vgic.c b/xen/arch/arm/vgic/vgic.c index b2c0e1873a..1c44236c4f 100644 --- a/xen/arch/arm/vgic/vgic.c +++ b/xen/arch/arm/vgic/vgic.c @@ -812,22 +812,27 @@ void arch_move_irqs(struct vcpu *v) { struct vgic_irq *irq =3D vgic_get_irq(d, NULL, i + VGIC_NR_PRIVATE= _IRQS); unsigned long flags; + irq_desc_t *desc; =20 if ( !irq ) continue; =20 - spin_lock_irqsave(&irq->irq_lock, flags); - - /* Only hardware mapped vIRQs that are targeting this vCPU. */ - if ( irq->hw && irq->target_vcpu =3D=3D v) + if ( !irq->hw ) { - irq_desc_t *desc =3D irq_to_desc(irq->hwintid); 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charset="utf-8" Move IRQs from dying CPU to the online ones when a CPU is getting offlined. When onlining, rebalance all IRQs in a round-robin fashion. Guest-bound IRQs are already handled by scheduler in the process of moving vCPUs to active pCPUs, so we only need to handle IRQs used by Xen itself. Signed-off-by: Mykyta Poturai --- v7->v8: * check only existings ESPIs v6->v7: * replace ifdef with IS_ENABLED v5->v6: * don't do any balancing on boot * only do balancing when cpu hotplug is enabled v4->v5: * handle CPU onlining as well * more comments * fix crash when ESPI is disabled * don't assume CPU 0 is a boot CPU * use insigned int for irq number * remove assumption that all irqs a bound to CPU 0 by default from the commit message v3->v4: * patch introduced --- xen/arch/arm/include/asm/irq.h | 6 ++++ xen/arch/arm/irq.c | 60 ++++++++++++++++++++++++++++++++++ xen/arch/arm/smpboot.c | 7 ++++ 3 files changed, 73 insertions(+) diff --git a/xen/arch/arm/include/asm/irq.h b/xen/arch/arm/include/asm/irq.h index 09788dbfeb..3ed55e02c3 100644 --- a/xen/arch/arm/include/asm/irq.h +++ b/xen/arch/arm/include/asm/irq.h @@ -126,6 +126,12 @@ bool irq_type_set_by_domain(const struct domain *d); void irq_end_none(struct irq_desc *irq); #define irq_end_none irq_end_none =20 +#ifdef CONFIG_CPU_HOTPLUG +void rebalance_irqs(unsigned int from, bool up); +#else +static inline void rebalance_irqs(unsigned int from, bool up) {} +#endif + #endif /* _ASM_HW_IRQ_H */ /* * Local variables: diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c index 7204bc2b68..44df7efd6b 100644 --- a/xen/arch/arm/irq.c +++ b/xen/arch/arm/irq.c @@ -158,6 +158,61 @@ static int init_local_irq_data(unsigned int cpu) return 0; } =20 +#ifdef CONFIG_CPU_HOTPLUG +static int cpu_next; + +static void balance_irq(int irq, unsigned int from, bool up) +{ + struct irq_desc *desc =3D irq_to_desc(irq); + unsigned long flags; + + ASSERT(!cpumask_empty(&cpu_online_map)); + + spin_lock_irqsave(&desc->lock, flags); + if ( likely(!desc->action) ) + goto out; + + if ( likely(test_bit(_IRQ_GUEST, &desc->status) || + test_bit(_IRQ_MOVE_PENDING, &desc->status)) ) + goto out; + + /* + * Setting affinity to a mask of multiple CPUs causes the GIC drivers = to + * select one CPU from that mask. If the dying CPU was included in the= IRQ's + * affinity mask, we cannot determine exactly which CPU the interrupt = is + * currently routed to, as GIC drivers lack a concrete get_affinity AP= I. So + * to be safe we must reroute it to a new, definitely online, CPU. In = the + * case of CPU going down, we move only the interrupt that could resid= e on + * it. Otherwise, we rearrange all interrupts in a round-robin fashion. + */ + if ( !up && !cpumask_test_cpu(from, desc->affinity) ) + goto out; + + cpu_next =3D cpumask_cycle(cpu_next, &cpu_online_map); + irq_set_affinity(desc, cpumask_of(cpu_next)); + +out: + spin_unlock_irqrestore(&desc->lock, flags); +} + +void rebalance_irqs(unsigned int from, bool up) +{ + int irq; + + if ( cpumask_empty(&cpu_online_map) ) + return; + + for ( irq =3D NR_LOCAL_IRQS; irq < NR_IRQS; irq++ ) + balance_irq(irq, from, up); + +#ifdef CONFIG_GICV3_ESPI + for ( irq =3D ESPI_BASE_INTID; irq < ESPI_BASE_INTID + gic_number_espi= s(); + irq++ ) + balance_irq(irq, from, up); +#endif +} +#endif /* CONFIG_CPU_HOTPLUG */ + static int cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) { @@ -172,6 +227,11 @@ static int cpu_callback(struct notifier_block *nfb, un= signed long action, printk(XENLOG_ERR "Unable to allocate local IRQ for CPU%u\n", cpu); break; + case CPU_ONLINE: + if ( IS_ENABLED(CONFIG_CPU_HOTPLUG) && + system_state >=3D SYS_STATE_active ) + rebalance_irqs(cpu, true); + break; } =20 return notifier_from_errno(rc); diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c index 7f3cfa812e..7d877179c0 100644 --- a/xen/arch/arm/smpboot.c +++ b/xen/arch/arm/smpboot.c @@ -425,6 +425,13 @@ void __cpu_disable(void) =20 smp_mb(); =20 + /* + * Now that the interrupts are cleared and the CPU marked as offline, + * move interrupts out of it + */ + if ( IS_ENABLED(CONFIG_CPU_HOTPLUG) ) + rebalance_irqs(cpu, false); + /* Return to caller; eventually the IPI mechanism will unwind and the=20 * scheduler will drop to the idle loop, which will call stop_cpu(). */ } --=20 2.51.2 From nobody Tue May 26 03:29:14 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; 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b=fqQD7vPhZw7AoNuMlqGaqGYHfrp4BL7/I8iwoq2IRuDvvdOzVgj6MLrjATXI8We7nrGRRCYj8g+2J8MCMypD6NLu4kG6k65nAVjUjMrjD6bmmpOv3/buR1RJj6JzDEsjW7FOFx3shOl9NptcUGBSrrc9J8cWJyVJlz4oUrKhryRHuJQb6oSOO3htaWRSo27p8nfudGrr/Gv1aUXutiDVuGGyWacxcZXCBxDxCovY7wib3TUy6QGXwE+vuiw7fE0g6XzEsWaUt4dpNile6aHG9RBBhzBrPi83stw+Enf2dCpLflncnPpBZVjj/s1y3et/i0zlpGz5Q6toIU9DUXzZ+Q== From: Mykyta Poturai To: "xen-devel@lists.xenproject.org" CC: Mykyta Poturai , Jan Beulich , Andrew Cooper , =?iso-8859-1?Q?Roger_Pau_Monn=E9?= , Teddy Astie , Anthony PERARD , Michal Orzel , Julien Grall , Stefano Stabellini Subject: [PATCH v8 3/6] Kconfig: Make cpu hotplug configurable Thread-Topic: [PATCH v8 3/6] Kconfig: Make cpu hotplug configurable Thread-Index: AQHc5GGmydFYeCVrlkigcpKCw3qy7w== Date: Fri, 15 May 2026 11:54:56 +0000 Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=epam.com; 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charset="utf-8" For the purposes of certification, we want as little code as possible to be unconditionally compiled in. Make CPU hotplug and SMT operations configurable to ease the process. This will also help with introducing CPU hotplug on Arm, where it needs to be configurable. Signed-off-by: Mykyta Poturai Acked-by: Jan Beulich --- v7->v8: * fix style * s/CPU_HOTPLUG/CPU_ONLINE_OFFLINE/ v6->v7: * new patch --- xen/arch/x86/platform_hypercall.c | 12 ++++++++++++ xen/arch/x86/smp.c | 3 +++ xen/arch/x86/sysctl.c | 12 ++++++++++++ xen/common/Kconfig | 8 ++++++++ 4 files changed, 35 insertions(+) diff --git a/xen/arch/x86/platform_hypercall.c b/xen/arch/x86/platform_hype= rcall.c index 0431f875af..3f6789c8b7 100644 --- a/xen/arch/x86/platform_hypercall.c +++ b/xen/arch/x86/platform_hypercall.c @@ -735,6 +735,12 @@ ret_t do_platform_op( { int cpu =3D op->u.cpu_ol.cpuid; =20 + if ( !IS_ENABLED(CONFIG_CPU_ONLINE_OFFLINE) ) + { + ret =3D -EOPNOTSUPP; + break; + } + ret =3D xsm_resource_plug_core(XSM_HOOK); if ( ret ) break; @@ -761,6 +767,12 @@ ret_t do_platform_op( { int cpu =3D op->u.cpu_ol.cpuid; =20 + if ( !IS_ENABLED(CONFIG_CPU_ONLINE_OFFLINE) ) + { + ret =3D -EOPNOTSUPP; + break; + } + ret =3D xsm_resource_unplug_core(XSM_HOOK); if ( ret ) break; diff --git a/xen/arch/x86/smp.c b/xen/arch/x86/smp.c index 7936294f5f..9046c826f8 100644 --- a/xen/arch/x86/smp.c +++ b/xen/arch/x86/smp.c @@ -418,6 +418,7 @@ void cf_check call_function_interrupt(void) smp_call_function_interrupt(); } =20 +#ifdef CONFIG_CPU_ONLINE_OFFLINE long cf_check cpu_up_helper(void *data) { unsigned int cpu =3D (unsigned long)data; @@ -445,8 +446,10 @@ long cf_check cpu_down_helper(void *data) { int cpu =3D (unsigned long)data; int ret =3D cpu_down(cpu); + /* Have one more go on EBUSY. */ if ( ret =3D=3D -EBUSY ) ret =3D cpu_down(cpu); return ret; } +#endif diff --git a/xen/arch/x86/sysctl.c b/xen/arch/x86/sysctl.c index 0fbbdd8b28..1d0857b502 100644 --- a/xen/arch/x86/sysctl.c +++ b/xen/arch/x86/sysctl.c @@ -53,6 +53,12 @@ static long cf_check smt_up_down_helper(void *data) unsigned int cpu, sibling_mask =3D boot_cpu_data.x86_num_siblings - 1; int ret =3D 0; =20 + if ( !IS_ENABLED(CONFIG_CPU_ONLINE_OFFLINE) ) + { + ASSERT_UNREACHABLE(); + return -EOPNOTSUPP; + } + opt_smt =3D up; =20 for_each_present_cpu ( cpu ) @@ -121,6 +127,12 @@ long arch_do_sysctl( long (*fn)(void *data); void *hcpu; =20 + if ( !IS_ENABLED(CONFIG_CPU_ONLINE_OFFLINE) ) + { + ret =3D -EOPNOTSUPP; + break; + } + switch ( op ) { case XEN_SYSCTL_CPU_HOTPLUG_ONLINE: diff --git a/xen/common/Kconfig b/xen/common/Kconfig index 0a20aa0a12..9fc53fde48 100644 --- a/xen/common/Kconfig +++ b/xen/common/Kconfig @@ -636,6 +636,14 @@ config SYSTEM_SUSPEND =20 If unsure, say N. =20 +config CPU_ONLINE_OFFLINE + bool "CPU online/offline support" + depends on X86 + default y + help + Enable support for bringing CPUs online and offline at runtime. 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charset="utf-8" SMT-disable enforcement check is moved into a separate architecture-specific function. For now this operations only support Arm64. For proper Arm32 support, there needs to be a mechanism to free per-cpu page tables, allocated in init_domheap_mappings. Also, hotplug is not supported if ITS enabled, and partially supported FFA, or TEE is enabled, as they use non-static IRQ actions. Remove ifdef guards for x86 in flask, as cpu hotplug is now supported on more architectures. Signed-off-by: Mykyta Poturai --- v7->v8: * simplify dependencies of config CPU_ONLINE_OFFLINE v6->v7: * use IS_ENABLED istead of ifdef in more places * remove unneded variables * more explicit fallthrough in do_sysctl v5->v6: * fix style issues * rename arch_smt_cpu_disable -> arch_cpu_can_stay_online and invert the logic * use IS_ENABLED istead of ifdef * remove explicit list af arch-specific SYSCTL_CPU_HOTPLUG_* options from the common handler * fix flask issue v4->v5: * move handling to common code * rename config to CPU_HOTPUG * merge with "smp: Move cpu_up/down helpers to common code" v3->v4: * don't reimplement cpu_up/down helpers * add Kconfig option * fixup formatting v2->v3: * no changes v1->v2: * remove SMT ops * remove cpu =3D=3D 0 checks * add XSM hooks * only implement for 64bit Arm Signed-off-by: Mykyta Poturai --- xen/arch/arm/smp.c | 9 ++++++++ xen/arch/ppc/stubs.c | 4 ++++ xen/arch/riscv/stubs.c | 5 ++++ xen/arch/x86/include/asm/smp.h | 3 --- xen/arch/x86/smp.c | 34 +++------------------------ xen/arch/x86/sysctl.c | 13 ++++------- xen/common/Kconfig | 6 ++--- xen/common/smp.c | 35 ++++++++++++++++++++++++++++ xen/common/sysctl.c | 42 ++++++++++++++++++++++++++++++++++ xen/include/xen/smp.h | 4 ++++ xen/xsm/flask/hooks.c | 2 -- 11 files changed, 109 insertions(+), 48 deletions(-) diff --git a/xen/arch/arm/smp.c b/xen/arch/arm/smp.c index b372472188..0ea64d2ee1 100644 --- a/xen/arch/arm/smp.c +++ b/xen/arch/arm/smp.c @@ -44,6 +44,15 @@ void smp_send_call_function_mask(const cpumask_t *mask) } } =20 +/* + * We currently don't support SMT on ARM so we don't need any special logi= c for + * CPU disabling + */ +inline bool arch_cpu_can_stay_online(unsigned int cpu) +{ + return true; +} + /* * Local variables: * mode: C diff --git a/xen/arch/ppc/stubs.c b/xen/arch/ppc/stubs.c index a333f06119..8f280ba080 100644 --- a/xen/arch/ppc/stubs.c +++ b/xen/arch/ppc/stubs.c @@ -101,6 +101,10 @@ void smp_send_call_function_mask(const cpumask_t *mask) BUG_ON("unimplemented"); } =20 +bool arch_cpu_can_stay_online(unsigned int cpu) +{ + BUG_ON("unimplemented"); +} /* irq.c */ =20 void irq_ack_none(struct irq_desc *desc) diff --git a/xen/arch/riscv/stubs.c b/xen/arch/riscv/stubs.c index acbb5b9123..e051f0fb3f 100644 --- a/xen/arch/riscv/stubs.c +++ b/xen/arch/riscv/stubs.c @@ -65,6 +65,11 @@ void smp_send_call_function_mask(const cpumask_t *mask) BUG_ON("unimplemented"); } =20 +bool arch_cpu_can_stay_online(unsigned int cpu) +{ + BUG_ON("unimplemented"); +} + /* irq.c */ =20 void irq_ack_none(struct irq_desc *desc) diff --git a/xen/arch/x86/include/asm/smp.h b/xen/arch/x86/include/asm/smp.h index 3f16e62696..cb3e0fed19 100644 --- a/xen/arch/x86/include/asm/smp.h +++ b/xen/arch/x86/include/asm/smp.h @@ -50,9 +50,6 @@ int cpu_add(uint32_t apic_id, uint32_t acpi_id, uint32_t = pxm); =20 void __stop_this_cpu(void); =20 -long cf_check cpu_up_helper(void *data); -long cf_check cpu_down_helper(void *data); - long cf_check core_parking_helper(void *data); bool core_parking_remove(unsigned int cpu); uint32_t get_cur_idle_nums(void); diff --git a/xen/arch/x86/smp.c b/xen/arch/x86/smp.c index 9046c826f8..caf4411705 100644 --- a/xen/arch/x86/smp.c +++ b/xen/arch/x86/smp.c @@ -419,37 +419,9 @@ void cf_check call_function_interrupt(void) } =20 #ifdef CONFIG_CPU_ONLINE_OFFLINE -long cf_check cpu_up_helper(void *data) +bool arch_cpu_can_stay_online(unsigned int cpu) { - unsigned int cpu =3D (unsigned long)data; - int ret =3D cpu_up(cpu); - - /* Have one more go on EBUSY. */ - if ( ret =3D=3D -EBUSY ) - ret =3D cpu_up(cpu); - - if ( !ret && !opt_smt && - cpu_data[cpu].compute_unit_id =3D=3D INVALID_CUID && - cpumask_weight(per_cpu(cpu_sibling_mask, cpu)) > 1 ) - { - ret =3D cpu_down_helper(data); - if ( ret ) - printk("Could not re-offline CPU%u (%d)\n", cpu, ret); - else - ret =3D -EPERM; - } - - return ret; -} - -long cf_check cpu_down_helper(void *data) -{ - int cpu =3D (unsigned long)data; - int ret =3D cpu_down(cpu); - - /* Have one more go on EBUSY. */ - if ( ret =3D=3D -EBUSY ) - ret =3D cpu_down(cpu); - return ret; + return opt_smt || cpu_data[cpu].compute_unit_id !=3D INVALID_CUID || + cpumask_weight(per_cpu(cpu_sibling_mask, cpu)) <=3D 1; } #endif diff --git a/xen/arch/x86/sysctl.c b/xen/arch/x86/sysctl.c index 1d0857b502..7a88ec7d7b 100644 --- a/xen/arch/x86/sysctl.c +++ b/xen/arch/x86/sysctl.c @@ -121,7 +121,6 @@ long arch_do_sysctl( =20 case XEN_SYSCTL_cpu_hotplug: { - unsigned int cpu =3D sysctl->u.cpu_hotplug.cpu; unsigned int op =3D sysctl->u.cpu_hotplug.op; bool plug; long (*fn)(void *data); @@ -129,6 +128,7 @@ long arch_do_sysctl( =20 if ( !IS_ENABLED(CONFIG_CPU_ONLINE_OFFLINE) ) { + ASSERT_UNREACHABLE(); ret =3D -EOPNOTSUPP; break; } @@ -136,15 +136,10 @@ long arch_do_sysctl( switch ( op ) { case XEN_SYSCTL_CPU_HOTPLUG_ONLINE: - plug =3D true; - fn =3D cpu_up_helper; - hcpu =3D _p(cpu); - break; - case XEN_SYSCTL_CPU_HOTPLUG_OFFLINE: - plug =3D false; - fn =3D cpu_down_helper; - hcpu =3D _p(cpu); + /* Handled by common code */ + ASSERT_UNREACHABLE(); + ret =3D -EOPNOTSUPP; break; =20 case XEN_SYSCTL_CPU_HOTPLUG_SMT_ENABLE: diff --git a/xen/common/Kconfig b/xen/common/Kconfig index 9fc53fde48..d0b8aa8d1c 100644 --- a/xen/common/Kconfig +++ b/xen/common/Kconfig @@ -637,9 +637,9 @@ config SYSTEM_SUSPEND If unsure, say N. =20 config CPU_ONLINE_OFFLINE - bool "CPU online/offline support" - depends on X86 - default y + bool "CPU online/offline support" if EXPERT + depends on X86 || (ARM_64 && !HAS_ITS) + default X86 help Enable support for bringing CPUs online and offline at runtime. On X86 this is required for disabling SMT. diff --git a/xen/common/smp.c b/xen/common/smp.c index a011f541f1..16f4ed2d4e 100644 --- a/xen/common/smp.c +++ b/xen/common/smp.c @@ -16,6 +16,7 @@ * GNU General Public License for more details. */ =20 +#include #include #include #include @@ -104,6 +105,40 @@ void smp_call_function_interrupt(void) irq_exit(); } =20 +#ifdef CONFIG_CPU_ONLINE_OFFLINE +long cf_check cpu_up_helper(void *data) +{ + unsigned int cpu =3D (unsigned long)data; + int ret =3D cpu_up(cpu); + + /* Have one more go on EBUSY. */ + if ( ret =3D=3D -EBUSY ) + ret =3D cpu_up(cpu); + + if ( !ret && !arch_cpu_can_stay_online(cpu) ) + { + ret =3D cpu_down_helper(data); + if ( ret ) + printk("Could not re-offline CPU%u (%d)\n", cpu, ret); + else + ret =3D -EPERM; + } + + return ret; +} + +long cf_check cpu_down_helper(void *data) +{ + unsigned int cpu =3D (unsigned long)data; + int ret =3D cpu_down(cpu); + + /* Have one more go on EBUSY. */ + if ( ret =3D=3D -EBUSY ) + ret =3D cpu_down(cpu); + return ret; +} +#endif /* CONFIG_CPU_ONLINE_OFFLINE */ + /* * Local variables: * mode: C diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c index 5207664252..f06aecb6f6 100644 --- a/xen/common/sysctl.c +++ b/xen/common/sysctl.c @@ -483,6 +483,48 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_= sysctl) copyback =3D 1; break; =20 + case XEN_SYSCTL_cpu_hotplug: + { + unsigned int hp_op =3D op->u.cpu_hotplug.op; + bool plug; + long (*fn)(void *data); + void *hcpu =3D _p(op->u.cpu_hotplug.cpu); + + ret =3D -EOPNOTSUPP; + if ( !IS_ENABLED(CONFIG_CPU_ONLINE_OFFLINE) ) + break; + + switch ( hp_op ) + { + case XEN_SYSCTL_CPU_HOTPLUG_ONLINE: + plug =3D true; + fn =3D cpu_up_helper; + break; + + case XEN_SYSCTL_CPU_HOTPLUG_OFFLINE: + plug =3D false; + fn =3D cpu_down_helper; + break; + + default: + fn =3D NULL; + break; + } + + if ( fn ) + { + ret =3D plug ? xsm_resource_plug_core(XSM_HOOK) + : xsm_resource_unplug_core(XSM_HOOK); + + if ( !ret ) + ret =3D continue_hypercall_on_cpu(0, fn, hcpu); + + break; + } + } + + /* Use the arch handler for cases not handled here */ + fallthrough; default: ret =3D arch_do_sysctl(op, u_sysctl); copyback =3D 0; diff --git a/xen/include/xen/smp.h b/xen/include/xen/smp.h index 2ca9ff1bfc..04530738c9 100644 --- a/xen/include/xen/smp.h +++ b/xen/include/xen/smp.h @@ -76,4 +76,8 @@ extern void *stack_base[NR_CPUS]; void initialize_cpu_data(unsigned int cpu); int setup_cpu_root_pgt(unsigned int cpu); =20 +bool arch_cpu_can_stay_online(unsigned int cpu); +long cf_check cpu_up_helper(void *data); +long cf_check cpu_down_helper(void *data); + #endif /* __XEN_SMP_H__ */ diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c index 28522dcbd2..4ee68231ce 100644 --- a/xen/xsm/flask/hooks.c +++ b/xen/xsm/flask/hooks.c @@ -835,9 +835,7 @@ static int cf_check flask_sysctl(int cmd) case XEN_SYSCTL_getdomaininfolist: case XEN_SYSCTL_page_offline_op: case XEN_SYSCTL_scheduler_op: -#ifdef CONFIG_X86 case XEN_SYSCTL_cpu_hotplug: -#endif return 0; =20 case XEN_SYSCTL_tbuf_op: --=20 2.51.2 From nobody Tue May 26 03:29:14 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; 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b=ob9ul3q8AiV8s9zs+fPGFQo/CHFkiuB7UP4FfQI7Z7IWv+v1eACE1ZJnfgWJ4vR328C3iqiDio/UTa8kXS60AADYjmax6Jr4+fliv8DwscPUqz5Gvo7ZMKiHz77WfgFkZbGKKhyUaicvS//wxHKBGu+An6zhDDuwQ05kfQUZyJ15CwtWYBeJ4b+wmGLmwtT+9P0tdvTirg23DvWumYihP1rVjg1mh842o5llgXMpNr+Ueqkc4Y2pdEvZJMzAmt694fwoYSZn8dmeQiV87Qdrf+eeNBYY661Wj6If7tAsEYoGlXXoSobhdEYJP52T8xJrc099fGD/8UrQCS/IOIUbXA== From: Mykyta Poturai To: "xen-devel@lists.xenproject.org" CC: Mykyta Poturai , Anthony PERARD Subject: [PATCH v8 5/6] tools: Allow building xen-hptool without CONFIG_MIGRATE Thread-Topic: [PATCH v8 5/6] tools: Allow building xen-hptool without CONFIG_MIGRATE Thread-Index: AQHc5GGmgZHFl4GybESq6ehOLkSGhw== Date: Fri, 15 May 2026 11:54:57 +0000 Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=epam.com; x-ms-publictraffictype: Email x-ms-traffictypediagnostic: PAVPR03MB10102:EE_|PAWPR03MB10041:EE_ x-ms-office365-filtering-correlation-id: 971da0c4-8372-455f-daec-08deb278c94b x-ms-exchange-senderadcheck: 1 x-ms-exchange-antispam-relay: 0 x-microsoft-antispam: BCL:0;ARA:13230040|376014|366016|1800799024|11063799003|22082099003|38070700021|56012099003|18002099003; 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charset="utf-8" With CPU hotplug sysctls implemented on Arm it becomes useful to have a tool for calling them. According to the commit history it seems that putting hptool under config MIGRATE was a measure to fix IA64 build. As IA64 is no longer supported it can now be brought back. So build it unconditionally. Operations specific to x86 architecture are moved into a separate file and = only built on x86. Signed-off-by: Mykyta Poturai --- v7->v8: * move x86 specific function into a separate file v6->v7: * no changes v5->v6: * don't change order in Makefile v4->v5: * make hptool always build v3->v4: * no changes v2->v3: * no changes v1->v2: * switch to configure from legacy config --- tools/misc/Makefile | 8 +- tools/misc/xen-hptool-x86.c | 277 ++++++++++++++++++++++++++++++++++ tools/misc/xen-hptool.c | 293 ++---------------------------------- tools/misc/xen-hptool.h | 14 ++ 4 files changed, 311 insertions(+), 281 deletions(-) create mode 100644 tools/misc/xen-hptool-x86.c create mode 100644 tools/misc/xen-hptool.h diff --git a/tools/misc/Makefile b/tools/misc/Makefile index 6ee783f43e..645819e455 100644 --- a/tools/misc/Makefile +++ b/tools/misc/Makefile @@ -16,7 +16,7 @@ INSTALL_BIN +=3D xencov_split INSTALL_BIN +=3D $(INSTALL_BIN-y) =20 # Everything to be installed in regular sbin/ -INSTALL_SBIN-$(CONFIG_MIGRATE) +=3D xen-hptool +INSTALL_SBIN +=3D xen-hptool INSTALL_SBIN-$(CONFIG_X86) +=3D xen-hvmcrash INSTALL_SBIN-$(CONFIG_X86) +=3D xen-hvmctx INSTALL_SBIN-$(CONFIG_X86) +=3D xen-lowmemd @@ -104,8 +104,10 @@ xenhypfs: xenhypfs.o xenlockprof: xenlockprof.o $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(APPEND_LDFLAGS) =20 -xen-hptool: xen-hptool.o - $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenevtchn) $(LDLIBS_libxenctrl) $(L= DLIBS_libxenguest) $(LDLIBS_libxenstore) $(APPEND_LDFLAGS) +HPTOOL_OBJS-$(CONFIG_MIGRATE) +=3D xen-hptool-x86.o + +xen-hptool: xen-hptool.o $(HPTOOL_OBJS-y) + $(CC) $(LDFLAGS) -o $@ $^ $(LDLIBS_libxenevtchn) $(LDLIBS_libxenctrl) $(L= DLIBS_libxenguest) $(LDLIBS_libxenstore) $(APPEND_LDFLAGS) =20 xenhypfs.o: CFLAGS +=3D $(CFLAGS_libxenhypfs) =20 diff --git a/tools/misc/xen-hptool-x86.c b/tools/misc/xen-hptool-x86.c new file mode 100644 index 0000000000..9336f30f1f --- /dev/null +++ b/tools/misc/xen-hptool-x86.c @@ -0,0 +1,277 @@ +#include +#include +#include +#include +#include +#include +#include +#include "xen-hptool.h" + +int hp_mem_online_func(int argc, char *argv[], xc_interface *xch) +{ + uint32_t status; + int ret; + unsigned long mfn; + + if (argc !=3D 1) + { + show_help(); + return -1; + } + + sscanf(argv[0], "%lx", &mfn); + printf("Prepare to online MEMORY mfn %lx\n", mfn); + + ret =3D xc_mark_page_online(xch, mfn, mfn, &status); + + if (ret < 0) + fprintf(stderr, "Onlining page mfn %lx failed, error %x\n", mfn, e= rrno); + else if (status & (PG_ONLINE_FAILED |PG_ONLINE_BROKEN)) { + fprintf(stderr, "Onlining page mfn %lx is broken, " + "Memory online failed\n", mfn); + ret =3D -1; + } + else if (status & PG_ONLINE_ONLINED) + printf("Memory mfn %lx onlined successfully\n", mfn); + else + printf("Memory is already onlined!\n"); + + return ret; +} + +int hp_mem_query_func(int argc, char *argv[], xc_interface *xch) +{ + uint32_t status; + int ret; + unsigned long mfn; + + if (argc !=3D 1) + { + show_help(); + return -1; + } + + sscanf(argv[0], "%lx", &mfn); + printf("Querying MEMORY mfn %lx status\n", mfn); + ret =3D xc_query_page_offline_status(xch, mfn, mfn, &status); + + if (ret < 0) + fprintf(stderr, "Querying page mfn %lx failed, error %x\n", mfn, e= rrno); + else + { + printf("Memory Status %x: [", status); + if ( status & PG_OFFLINE_STATUS_OFFLINE_PENDING) + printf(" PAGE_OFFLINE_PENDING "); + if ( status & PG_OFFLINE_STATUS_BROKEN ) + printf(" PAGE_BROKEND "); + if ( status & PG_OFFLINE_STATUS_OFFLINED ) + printf(" PAGE_OFFLINED "); + else + printf(" PAGE_ONLINED "); + printf("]\n"); + } + + return ret; +} + +static int suspend_guest(xc_interface *xch, xenevtchn_handle *xce, int dom= id, + int *evtchn, int *lockfd) +{ + int port, rc, suspend_evtchn =3D -1; + + *lockfd =3D -1; + + if (!evtchn) + return -1; + + port =3D xs_suspend_evtchn_port(domid); + if (port < 0) + { + fprintf(stderr, "DOM%d: No suspend port, try live migration\n", do= mid); + goto failed; + } + suspend_evtchn =3D xc_suspend_evtchn_init_exclusive(xch, xce, domid, + port, lockfd); + if (suspend_evtchn < 0) + { + fprintf(stderr, "Suspend evtchn initialization failed\n"); + goto failed; + } + *evtchn =3D suspend_evtchn; + + rc =3D xenevtchn_notify(xce, suspend_evtchn); + if (rc < 0) + { + fprintf(stderr, "Failed to notify suspend channel: errno %d\n", rc= ); + goto failed; + } + if (xc_await_suspend(xch, xce, suspend_evtchn) < 0) + { + fprintf(stderr, "Suspend Failed\n"); + goto failed; + } + return 0; + +failed: + if (suspend_evtchn !=3D -1) + xc_suspend_evtchn_release(xch, xce, domid, + suspend_evtchn, lockfd); + + return -1; +} + +int hp_mem_offline_func(int argc, char *argv[], xc_interface *xch) +{ + uint32_t status, domid; + int ret; + unsigned long mfn; + + if (argc !=3D 1) + { + show_help(); + return -1; + } + + sscanf(argv[0], "%lx", &mfn); + printf("Prepare to offline MEMORY mfn %lx\n", mfn); + ret =3D xc_mark_page_offline(xch, mfn, mfn, &status); + if (ret < 0) { + fprintf(stderr, "Offlining page mfn %lx failed, error %x\n", mfn, = errno); + if (status & (PG_OFFLINE_XENPAGE | PG_OFFLINE_FAILED)) + fprintf(stderr, "XEN_PAGE is not permitted be offlined\n"); + else if (status & (PG_OFFLINE_FAILED | PG_OFFLINE_NOT_CONV_RAM)) + fprintf(stderr, "RESERVED RAM is not permitted to be offlined\= n"); + } + else + { + switch(status & PG_OFFLINE_STATUS_MASK) + { + case PG_OFFLINE_OFFLINED: + { + printf("Memory mfn %lx offlined successfully, current stat= e is" + " [PG_OFFLINE_OFFLINED]\n", mfn); + if (status & PG_OFFLINE_BROKEN) + printf("And this offlined PAGE is already marked broke= n" + " before!\n"); + break; + } + case PG_OFFLINE_FAILED: + { + fprintf(stderr, "Memory mfn %lx offline failed\n", mfn); + if ( status & PG_OFFLINE_ANONYMOUS) + fprintf(stderr, "the memory is an anonymous page!\n"); + ret =3D -1; + break; + } + case PG_OFFLINE_PENDING: + { + if (status & PG_OFFLINE_XENPAGE) { + ret =3D -1; + fprintf(stderr, "Memory mfn %lx offlined succssefully," + "this page is xen page, current state is" + " [PG_OFFLINE_PENDING, PG_OFFLINE_XENPAGE]\n",= mfn); + } + else if (status & PG_OFFLINE_OWNED) + { + int result, suspend_evtchn =3D -1, suspend_lockfd =3D = -1; + xenevtchn_handle *xce; + xce =3D xenevtchn_open(NULL, 0); + + if (xce =3D=3D NULL) + { + fprintf(stderr, "When exchange page, fail" + " to open evtchn\n"); + return -1; + } + + domid =3D status >> PG_OFFLINE_OWNER_SHIFT; + if (suspend_guest(xch, xce, domid, + &suspend_evtchn, &suspend_lockfd)) + { + fprintf(stderr, "Failed to suspend guest %d for" + " mfn %lx\n", domid, mfn); + xenevtchn_close(xce); + return -1; + } + + result =3D xc_exchange_page(xch, domid, mfn); + + /* Exchange page successfully */ + if (result =3D=3D 0) + printf("Memory mfn %lx offlined successfully, this= " + "page is DOM%d page and being swapped " + "successfully, current state is " + "[PG_OFFLINE_OFFLINED, PG_OFFLINE_OWNED]\n= ", + mfn, domid); + else { + ret =3D -1; + fprintf(stderr, "Memory mfn %lx offlined successfu= lly" + " , this page is DOM%d page yet failed to = be " + "exchanged. current state is " + "[PG_OFFLINE_PENDING, PG_OFFLINE_OWNED]\n", + mfn, domid); + } + xc_domain_resume(xch, domid, 1); + xc_suspend_evtchn_release(xch, xce, domid, + suspend_evtchn, &suspend_loc= kfd); + xenevtchn_close(xce); + } + break; + } + }//end of switch + }//end of if + + return ret; +} + +int main_smt_enable(int argc, char *argv[], xc_interface *xch) +{ + int ret; + + if ( argc ) + { + show_help(); + return -1; + } + + for ( ;; ) + { + ret =3D xc_smt_enable(xch); + if ( (ret >=3D 0) || (errno !=3D EBUSY) ) + break; + } + + if ( ret < 0 ) + fprintf(stderr, "Unable to enable SMT: errno %d, %s\n", + errno, strerror(errno)); + else + printf("Enabled SMT\n"); + + return ret; +} + +int main_smt_disable(int argc, char *argv[], xc_interface *xch) +{ + int ret; + + if ( argc ) + { + show_help(); + return -1; + } + + for ( ;; ) + { + ret =3D xc_smt_disable(xch); + if ( (ret >=3D 0) || (errno !=3D EBUSY) ) + break; + } + + if ( ret < 0 ) + fprintf(stderr, "Unable to disable SMT: errno %d, %s\n", + errno, strerror(errno)); + else + printf("Disabled SMT\n"); + + return ret; +} diff --git a/tools/misc/xen-hptool.c b/tools/misc/xen-hptool.c index 590810b6eb..7b886e2304 100644 --- a/tools/misc/xen-hptool.c +++ b/tools/misc/xen-hptool.c @@ -6,8 +6,8 @@ #include #include #include +#include "xen-hptool.h" =20 -static xc_interface *xch; =20 void show_help(void) { @@ -18,239 +18,25 @@ void show_help(void) " help display this help\n" " cpu-online online CPU \n" " cpu-offline offline CPU \n" +#if defined(__i386__) || defined(__x86_64__) " mem-online online MEMORY \n" " mem-offline offline MEMORY \n" " mem-status query Memory status\n" " smt-enable onlines all SMT threads\n" " smt-disable offlines all SMT threads\n" +#endif ); } =20 /* wrapper function */ -static int help_func(int argc, char *argv[]) +static int help_func(int argc, char *argv[], xc_interface *xch) { show_help(); return 0; } =20 -static int hp_mem_online_func(int argc, char *argv[]) -{ - uint32_t status; - int ret; - unsigned long mfn; - - if (argc !=3D 1) - { - show_help(); - return -1; - } - - sscanf(argv[0], "%lx", &mfn); - printf("Prepare to online MEMORY mfn %lx\n", mfn); - - ret =3D xc_mark_page_online(xch, mfn, mfn, &status); - - if (ret < 0) - fprintf(stderr, "Onlining page mfn %lx failed, error %x\n", mfn, e= rrno); - else if (status & (PG_ONLINE_FAILED |PG_ONLINE_BROKEN)) { - fprintf(stderr, "Onlining page mfn %lx is broken, " - "Memory online failed\n", mfn); - ret =3D -1; - } - else if (status & PG_ONLINE_ONLINED) - printf("Memory mfn %lx onlined successfully\n", mfn); - else - printf("Memory is already onlined!\n"); - - return ret; -} - -static int hp_mem_query_func(int argc, char *argv[]) -{ - uint32_t status; - int ret; - unsigned long mfn; - - if (argc !=3D 1) - { - show_help(); - return -1; - } - - sscanf(argv[0], "%lx", &mfn); - printf("Querying MEMORY mfn %lx status\n", mfn); - ret =3D xc_query_page_offline_status(xch, mfn, mfn, &status); - - if (ret < 0) - fprintf(stderr, "Querying page mfn %lx failed, error %x\n", mfn, e= rrno); - else - { - printf("Memory Status %x: [", status); - if ( status & PG_OFFLINE_STATUS_OFFLINE_PENDING) - printf(" PAGE_OFFLINE_PENDING "); - if ( status & PG_OFFLINE_STATUS_BROKEN ) - printf(" PAGE_BROKEND "); - if ( status & PG_OFFLINE_STATUS_OFFLINED ) - printf(" PAGE_OFFLINED "); - else - printf(" PAGE_ONLINED "); - printf("]\n"); - } - - return ret; -} - -static int suspend_guest(xc_interface *xch, xenevtchn_handle *xce, int dom= id, - int *evtchn, int *lockfd) -{ - int port, rc, suspend_evtchn =3D -1; - - *lockfd =3D -1; - - if (!evtchn) - return -1; - - port =3D xs_suspend_evtchn_port(domid); - if (port < 0) - { - fprintf(stderr, "DOM%d: No suspend port, try live migration\n", do= mid); - goto failed; - } - suspend_evtchn =3D xc_suspend_evtchn_init_exclusive(xch, xce, domid, - port, lockfd); - if (suspend_evtchn < 0) - { - fprintf(stderr, "Suspend evtchn initialization failed\n"); - goto failed; - } - *evtchn =3D suspend_evtchn; - - rc =3D xenevtchn_notify(xce, suspend_evtchn); - if (rc < 0) - { - fprintf(stderr, "Failed to notify suspend channel: errno %d\n", rc= ); - goto failed; - } - if (xc_await_suspend(xch, xce, suspend_evtchn) < 0) - { - fprintf(stderr, "Suspend Failed\n"); - goto failed; - } - return 0; - -failed: - if (suspend_evtchn !=3D -1) - xc_suspend_evtchn_release(xch, xce, domid, - suspend_evtchn, lockfd); - - return -1; -} - -static int hp_mem_offline_func(int argc, char *argv[]) -{ - uint32_t status, domid; - int ret; - unsigned long mfn; - - if (argc !=3D 1) - { - show_help(); - return -1; - } - - sscanf(argv[0], "%lx", &mfn); - printf("Prepare to offline MEMORY mfn %lx\n", mfn); - ret =3D xc_mark_page_offline(xch, mfn, mfn, &status); - if (ret < 0) { - fprintf(stderr, "Offlining page mfn %lx failed, error %x\n", mfn, = errno); - if (status & (PG_OFFLINE_XENPAGE | PG_OFFLINE_FAILED)) - fprintf(stderr, "XEN_PAGE is not permitted be offlined\n"); - else if (status & (PG_OFFLINE_FAILED | PG_OFFLINE_NOT_CONV_RAM)) - fprintf(stderr, "RESERVED RAM is not permitted to be offlined\= n"); - } - else - { - switch(status & PG_OFFLINE_STATUS_MASK) - { - case PG_OFFLINE_OFFLINED: - { - printf("Memory mfn %lx offlined successfully, current stat= e is" - " [PG_OFFLINE_OFFLINED]\n", mfn); - if (status & PG_OFFLINE_BROKEN) - printf("And this offlined PAGE is already marked broke= n" - " before!\n"); - break; - } - case PG_OFFLINE_FAILED: - { - fprintf(stderr, "Memory mfn %lx offline failed\n", mfn); - if ( status & PG_OFFLINE_ANONYMOUS) - fprintf(stderr, "the memory is an anonymous page!\n"); - ret =3D -1; - break; - } - case PG_OFFLINE_PENDING: - { - if (status & PG_OFFLINE_XENPAGE) { - ret =3D -1; - fprintf(stderr, "Memory mfn %lx offlined succssefully," - "this page is xen page, current state is" - " [PG_OFFLINE_PENDING, PG_OFFLINE_XENPAGE]\n",= mfn); - } - else if (status & PG_OFFLINE_OWNED) - { - int result, suspend_evtchn =3D -1, suspend_lockfd =3D = -1; - xenevtchn_handle *xce; - xce =3D xenevtchn_open(NULL, 0); - - if (xce =3D=3D NULL) - { - fprintf(stderr, "When exchange page, fail" - " to open evtchn\n"); - return -1; - } - - domid =3D status >> PG_OFFLINE_OWNER_SHIFT; - if (suspend_guest(xch, xce, domid, - &suspend_evtchn, &suspend_lockfd)) - { - fprintf(stderr, "Failed to suspend guest %d for" - " mfn %lx\n", domid, mfn); - xenevtchn_close(xce); - return -1; - } - - result =3D xc_exchange_page(xch, domid, mfn); - - /* Exchange page successfully */ - if (result =3D=3D 0) - printf("Memory mfn %lx offlined successfully, this= " - "page is DOM%d page and being swapped " - "successfully, current state is " - "[PG_OFFLINE_OFFLINED, PG_OFFLINE_OWNED]\n= ", - mfn, domid); - else { - ret =3D -1; - fprintf(stderr, "Memory mfn %lx offlined successfu= lly" - " , this page is DOM%d page yet failed to = be " - "exchanged. current state is " - "[PG_OFFLINE_PENDING, PG_OFFLINE_OWNED]\n", - mfn, domid); - } - xc_domain_resume(xch, domid, 1); - xc_suspend_evtchn_release(xch, xce, domid, - suspend_evtchn, &suspend_loc= kfd); - xenevtchn_close(xce); - } - break; - } - }//end of switch - }//end of if - - return ret; -} - -static int exec_cpu_hp_fn(int (*hp_fn)(xc_interface *, int), int cpu) +static int exec_cpu_hp_fn(int (*hp_fn)(xc_interface *, int), int cpu, + xc_interface *xch) { int ret; =20 @@ -265,7 +51,7 @@ static int exec_cpu_hp_fn(int (*hp_fn)(xc_interface *, i= nt), int cpu) return ret; } =20 -static int hp_cpu_online_func(int argc, char *argv[]) +static int hp_cpu_online_func(int argc, char *argv[], xc_interface *xch) { int cpu, ret; =20 @@ -277,7 +63,7 @@ static int hp_cpu_online_func(int argc, char *argv[]) =20 cpu =3D atoi(argv[0]); printf("Prepare to online CPU %d\n", cpu); - ret =3D exec_cpu_hp_fn(xc_cpu_online, cpu); + ret =3D exec_cpu_hp_fn(xc_cpu_online, cpu, xch); if (ret < 0) fprintf(stderr, "CPU %d online failed (error %d: %s)\n", cpu, errno, strerror(errno)); @@ -287,7 +73,7 @@ static int hp_cpu_online_func(int argc, char *argv[]) return ret; =20 } -static int hp_cpu_offline_func(int argc, char *argv[]) +static int hp_cpu_offline_func(int argc, char *argv[], xc_interface *xch) { int cpu, ret; =20 @@ -298,7 +84,7 @@ static int hp_cpu_offline_func(int argc, char *argv[]) } cpu =3D atoi(argv[0]); printf("Prepare to offline CPU %d\n", cpu); - ret =3D exec_cpu_hp_fn(xc_cpu_offline, cpu); + ret =3D exec_cpu_hp_fn(xc_cpu_offline, cpu, xch); if (ret < 0) fprintf(stderr, "CPU %d offline failed (error %d: %s)\n", cpu, errno, strerror(errno)); @@ -308,76 +94,27 @@ static int hp_cpu_offline_func(int argc, char *argv[]) return ret; } =20 -static int main_smt_enable(int argc, char *argv[]) -{ - int ret; - - if ( argc ) - { - show_help(); - return -1; - } - - for ( ;; ) - { - ret =3D xc_smt_enable(xch); - if ( (ret >=3D 0) || (errno !=3D EBUSY) ) - break; - } - - if ( ret < 0 ) - fprintf(stderr, "Unable to enable SMT: errno %d, %s\n", - errno, strerror(errno)); - else - printf("Enabled SMT\n"); - - return ret; -} - -static int main_smt_disable(int argc, char *argv[]) -{ - int ret; - - if ( argc ) - { - show_help(); - return -1; - } - - for ( ;; ) - { - ret =3D xc_smt_disable(xch); - if ( (ret >=3D 0) || (errno !=3D EBUSY) ) - break; - } - - if ( ret < 0 ) - fprintf(stderr, "Unable to disable SMT: errno %d, %s\n", - errno, strerror(errno)); - else - printf("Disabled SMT\n"); - - return ret; -} - struct { const char *name; - int (*function)(int argc, char *argv[]); + int (*function)(int argc, char *argv[], xc_interface *xch); } main_options[] =3D { { "help", help_func }, { "cpu-online", hp_cpu_online_func }, { "cpu-offline", hp_cpu_offline_func }, +#if defined(__i386__) || defined(__x86_64__) { "mem-status", hp_mem_query_func}, { "mem-online", hp_mem_online_func}, { "mem-offline", hp_mem_offline_func}, { "smt-enable", main_smt_enable }, { "smt-disable", main_smt_disable }, +#endif }; =20 =20 int main(int argc, char *argv[]) { int i, ret; + xc_interface *xch; =20 if (argc < 2) { @@ -402,7 +139,7 @@ int main(int argc, char *argv[]) return 1; } =20 - ret =3D main_options[i].function(argc -2, argv + 2); + ret =3D main_options[i].function(argc -2, argv + 2, xch); =20 xc_interface_close(xch); =20 diff --git a/tools/misc/xen-hptool.h b/tools/misc/xen-hptool.h new file mode 100644 index 0000000000..2efa7c8177 --- /dev/null +++ b/tools/misc/xen-hptool.h @@ -0,0 +1,14 @@ +#ifndef __XEN_HPTOOL_H__ +#define __XEN_HPTOOL_H__ + +#if defined(__i386__) || defined(__x86_64__) +int hp_mem_online_func(int argc, char *argv[], xc_interface *xch); +int hp_mem_query_func(int argc, char *argv[], xc_interface *xch); +int hp_mem_offline_func(int argc, char *argv[], xc_interface *xch); +int main_smt_enable(int argc, char *argv[], xc_interface *xch); +int main_smt_disable(int argc, char *argv[], xc_interface *xch); +#endif + +void show_help(void); + +#endif /* __XEN_HPTOOL_H__ */ --=20 2.51.2 From nobody Tue May 26 03:29:14 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; 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charset="utf-8" Signed-off-by: Mykyta Poturai --- v7->v8: * remove support status update * update config option name v6->v7: * add testing and limitations v5->v6: * no changes v4->v5: * s/supported/implemented/ * update SUPPORT.md v3->v4: * update configuration section v2->v3: * patch introduced --- docs/misc/cpu-hotplug.txt | 97 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+) create mode 100644 docs/misc/cpu-hotplug.txt diff --git a/docs/misc/cpu-hotplug.txt b/docs/misc/cpu-hotplug.txt new file mode 100644 index 0000000000..d2ed1d6b8b --- /dev/null +++ b/docs/misc/cpu-hotplug.txt @@ -0,0 +1,97 @@ +CPU Hotplug +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +CPU hotplug is a feature that allows pCPU cores to be added to or removed = from a +running system without requiring a reboot. It is implemented on x86 and Ar= m64 +architectures. + +Implementation Details +---------------------- + +CPU hotplug is implemented through the `XEN_SYSCTL_CPU_HOTPLUG_*` sysctl c= alls. +The specific calls are: + +- `XEN_SYSCTL_CPU_HOTPLUG_ONLINE`: Brings a pCPU online +- `XEN_SYSCTL_CPU_HOTPLUG_OFFLINE`: Takes a pCPU offline +- `XEN_SYSCTL_CPU_HOTPLUG_SMT_ENABLE`: Enables SMT threads (x86 only) +- `XEN_SYSCTL_CPU_HOTPLUG_SMT_DISABLE`: Disables SMT threads (x86 only) + +All cores can be disabled, assuming hardware support, except for the boot = core. +Sysctl calls are routed to the boot core before doing any actual up/down +operations on other cores. + +If there are Xen-bound interrupts pinned to the pCPU being offlined, they = will +be automatically migrated to other online pCPUs. Interrupts used by guest +domains are handled by the scheduler when it reschedules the vCPUs to a ne= w, +online, pCPU. When a pCPU is being onlined, some Xen-bound interrupts will= get +redistributed to the newly onlined pCPU to prevent imbalance. + +If pCPU being offlined has some vCPUs pinned to it, they will be automatic= ally +unpinned and migrated to other online pCPUs. + +Limitations +----------- + +On Arm64 cpu hotplug is currently not compatible with ITS, due to an issue= s with +the redistributor assignment. + +On Arm64 there can be problems with FFA if secure FW support notification = ABI. + +Configuration +------------- + +The presence of the feature is controlled by CONFIG_CPU_ONLINE_OFFLINE opt= ion. +It is enabled by default on x86 architecture. On Arm64, the option is disa= bled +by default and marked as EXPERT. xen-hptool userspace tool is built +unconditionally. + +Usage +----- + +Disable core: + +$ xen-hptool cpu-offline 2 +Prepare to offline CPU 2 +(XEN) Removing cpu 2 from runqueue 0 +CPU 2 offlined successfully + +Enable core: + +$ xen-hptool cpu-online 2 +Prepare to online CPU 2 +(XEN) Bringing up CPU2 +(XEN) GICv3: CPU2: Found redistributor in region 0 @00000a004005c000 +(XEN) CPU2: Guest atomics will try 1 times before pausing the domain +(XEN) CPU 2 booted. +(XEN) Adding cpu 2 to runqueue 0 +CPU 2 onlined successfully + +Disabling a core with pinned vCPUs: + +$ xl vcpu-pin 0 3 3 3 +$ xl vcpu-pin 0 2 3 3 +$ xl vcpu-pin 0 1 3 3 +$ xl vcpu-pin 0 0 3 3 +$ xen-hptool cpu-offline 3 +Prepare to offline CPU 3 +(XEN) Breaking affinity for d0v0 +(XEN) Breaking affinity for d0v1 +(XEN) Breaking affinity for d0v2 +(XEN) Breaking affinity for d0v3 +(XEN) Removing cpu 3 from runqueue 0 +CPU 3 offlined successfully + +Testing +------- + +The CPU hotplug feature has been tested on both x86 and Arm64 QEMU setups = and on +R-Car Gen5 (Arm64) hardware. + +The tests included: +- Offlining and onlining cores with no pinned vCPUs +- Offlining cores with pinned vCPUs +- Offlining cores with Xen-bound interrupts +- Offlining all cores except the boot core +- Offlining the boot core (expected to fail) +- Enabling and disabling SMT threads (x86 only) +- Ofllining cores to which guests with passthrough devices are pinned --=20 2.51.2