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[104.155.91.135]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490ea4b39e9sm210485135e9.0.2026.06.15.05.59.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Jun 2026 05:59:14 -0700 (PDT) Date: Mon, 15 Jun 2026 13:59:10 +0100 From: Vincent Donnefort To: tabba@google.com Cc: Marc Zyngier , Oliver Upton , Will Deacon , Catalin Marinas , Quentin Perret , Sebastian Ene , Per Larsen , Suzuki K Poulose , Zenghui Yu , Joey Gouly , Steffen Eiden , Mark Rutland , Jonathan Cameron , Hyunwoo Kim , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 03/11] KVM: arm64: Use guard()/scoped_guard() in arm64 KVM EL1 code Message-ID: References: <20260612065925.755562-1-tabba@google.com> <20260612065925.755562-4-tabba@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260612065925.755562-4-tabba@google.com> On Fri, Jun 12, 2026 at 07:59:17AM +0100, tabba@google.com wrote: > Convert the manual mutex_lock()/spin_lock() pairs in > arch/arm64/kvm/{pkvm,arm,mmu,reset,psci}.c to guard(mutex), > guard(spinlock) and scoped_guard(), dropping unlock-only goto labels in > favour of direct returns. Centralised cleanup gotos that still serve > other resources are preserved. > > reset.c uses scoped_guard() rather than guard() so the lock covers only > the small read/update window inside kvm_reset_vcpu(), leaving the rest > of the function outside the critical section. I believe in that case unless it really helps with cleaning resources, there's not much point using scoped_guard(). I would keep it as is. > > Signed-off-by: Fuad Tabba > --- > arch/arm64/kvm/arm.c | 14 +++----- > arch/arm64/kvm/mmu.c | 80 +++++++++++++++--------------------------- > arch/arm64/kvm/pkvm.c | 26 ++++++-------- > arch/arm64/kvm/psci.c | 17 ++++----- > arch/arm64/kvm/reset.c | 8 ++--- > 5 files changed, 53 insertions(+), 92 deletions(-) > > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index 9453321ef8c6..c9f36932c980 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -793,9 +793,7 @@ int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu, > int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu, > struct kvm_mp_state *mp_state) > { > - int ret = 0; > - > - spin_lock(&vcpu->arch.mp_state_lock); > + guard(spinlock)(&vcpu->arch.mp_state_lock); > > switch (mp_state->mp_state) { > case KVM_MP_STATE_RUNNABLE: > @@ -808,12 +806,10 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu, > kvm_arm_vcpu_suspend(vcpu); > break; > default: > - ret = -EINVAL; > + return -EINVAL; > } > > - spin_unlock(&vcpu->arch.mp_state_lock); > - > - return ret; > + return 0; > } > > /** > @@ -1726,15 +1722,13 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu, > /* > * Handle the "start in power-off" case. > */ > - spin_lock(&vcpu->arch.mp_state_lock); > + guard(spinlock)(&vcpu->arch.mp_state_lock); > > if (power_off) > __kvm_arm_vcpu_power_off(vcpu); > else > WRITE_ONCE(vcpu->arch.mp_state.mp_state, KVM_MP_STATE_RUNNABLE); > > - spin_unlock(&vcpu->arch.mp_state_lock); > - > return 0; > } > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 4da9281312eb..d18f4ce7ceae 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -391,13 +391,13 @@ static void stage2_flush_vm(struct kvm *kvm) > */ > void __init free_hyp_pgds(void) > { > - mutex_lock(&kvm_hyp_pgd_mutex); > - if (hyp_pgtable) { > - kvm_pgtable_hyp_destroy(hyp_pgtable); > - kfree(hyp_pgtable); > - hyp_pgtable = NULL; > - } > - mutex_unlock(&kvm_hyp_pgd_mutex); > + guard(mutex)(&kvm_hyp_pgd_mutex); > + if (!hyp_pgtable) > + return; > + > + kvm_pgtable_hyp_destroy(hyp_pgtable); > + kfree(hyp_pgtable); > + hyp_pgtable = NULL; > } > > static bool kvm_host_owns_hyp_mappings(void) > @@ -424,16 +424,11 @@ static bool kvm_host_owns_hyp_mappings(void) > int __create_hyp_mappings(unsigned long start, unsigned long size, > unsigned long phys, enum kvm_pgtable_prot prot) > { > - int err; > - > if (WARN_ON(!kvm_host_owns_hyp_mappings())) > return -EINVAL; > > - mutex_lock(&kvm_hyp_pgd_mutex); > - err = kvm_pgtable_hyp_map(hyp_pgtable, start, size, phys, prot); > - mutex_unlock(&kvm_hyp_pgd_mutex); > - > - return err; > + guard(mutex)(&kvm_hyp_pgd_mutex); > + return kvm_pgtable_hyp_map(hyp_pgtable, start, size, phys, prot); > } > > static phys_addr_t kvm_kaddr_to_phys(void *kaddr) > @@ -481,56 +476,42 @@ static int share_pfn_hyp(u64 pfn) > { > struct rb_node **node, *parent; > struct hyp_shared_pfn *this; > - int ret = 0; > > - mutex_lock(&hyp_shared_pfns_lock); > + guard(mutex)(&hyp_shared_pfns_lock); > this = find_shared_pfn(pfn, &node, &parent); > if (this) { > this->count++; > - goto unlock; > + return 0; > } > > this = kzalloc_obj(*this); > - if (!this) { > - ret = -ENOMEM; > - goto unlock; > - } > + if (!this) > + return -ENOMEM; > > this->pfn = pfn; > this->count = 1; > rb_link_node(&this->node, parent, node); > rb_insert_color(&this->node, &hyp_shared_pfns); > - ret = kvm_call_hyp_nvhe(__pkvm_host_share_hyp, pfn); > -unlock: > - mutex_unlock(&hyp_shared_pfns_lock); > - > - return ret; > + return kvm_call_hyp_nvhe(__pkvm_host_share_hyp, pfn); > } > > static int unshare_pfn_hyp(u64 pfn) > { > struct rb_node **node, *parent; > struct hyp_shared_pfn *this; > - int ret = 0; > > - mutex_lock(&hyp_shared_pfns_lock); > + guard(mutex)(&hyp_shared_pfns_lock); > this = find_shared_pfn(pfn, &node, &parent); > - if (WARN_ON(!this)) { > - ret = -ENOENT; > - goto unlock; > - } > + if (WARN_ON(!this)) > + return -ENOENT; > > this->count--; > if (this->count) > - goto unlock; > + return 0; > > rb_erase(&this->node, &hyp_shared_pfns); > kfree(this); > - ret = kvm_call_hyp_nvhe(__pkvm_host_unshare_hyp, pfn); > -unlock: > - mutex_unlock(&hyp_shared_pfns_lock); > - > - return ret; > + return kvm_call_hyp_nvhe(__pkvm_host_unshare_hyp, pfn); > } > > int kvm_share_hyp(void *from, void *to) > @@ -655,7 +636,7 @@ int hyp_alloc_private_va_range(size_t size, unsigned long *haddr) > unsigned long base; > int ret = 0; > > - mutex_lock(&kvm_hyp_pgd_mutex); > + guard(mutex)(&kvm_hyp_pgd_mutex); > > /* > * This assumes that we have enough space below the idmap > @@ -670,8 +651,6 @@ int hyp_alloc_private_va_range(size_t size, unsigned long *haddr) > base = io_map_base - size; > ret = __hyp_alloc_private_va_range(base); > > - mutex_unlock(&kvm_hyp_pgd_mutex); > - > if (!ret) > *haddr = base; > > @@ -714,17 +693,16 @@ int create_hyp_stack(phys_addr_t phys_addr, unsigned long *haddr) > size_t size; > int ret; > > - mutex_lock(&kvm_hyp_pgd_mutex); > - /* > - * Efficient stack verification using the NVHE_STACK_SHIFT bit implies > - * an alignment of our allocation on the order of the size. > - */ > - size = NVHE_STACK_SIZE * 2; > - base = ALIGN_DOWN(io_map_base - size, size); > + scoped_guard(mutex, &kvm_hyp_pgd_mutex) { > + /* > + * Efficient stack verification using the NVHE_STACK_SHIFT bit implies > + * an alignment of our allocation on the order of the size. > + */ > + size = NVHE_STACK_SIZE * 2; > + base = ALIGN_DOWN(io_map_base - size, size); > > - ret = __hyp_alloc_private_va_range(base); > - > - mutex_unlock(&kvm_hyp_pgd_mutex); > + ret = __hyp_alloc_private_va_range(base); > + } Not sure about that one, it's not shorter, doesn't remove any label but add a tab. > > if (ret) { > kvm_err("Cannot allocate hyp stack guard page\n"); > diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c > index 053e4f733e4b..a39111b70f9f 100644 > --- a/arch/arm64/kvm/pkvm.c > +++ b/arch/arm64/kvm/pkvm.c > @@ -190,39 +190,33 @@ bool pkvm_hyp_vm_is_created(struct kvm *kvm) > > int pkvm_create_hyp_vm(struct kvm *kvm) > { > - int ret = 0; > - > /* > * Synchronise with kvm_arch_prepare_memory_region(), as we > * prevent memslot modifications on a pVM that has been run. > */ > - mutex_lock(&kvm->slots_lock); > - mutex_lock(&kvm->arch.config_lock); > - if (!pkvm_hyp_vm_is_created(kvm)) > - ret = __pkvm_create_hyp_vm(kvm); > - mutex_unlock(&kvm->arch.config_lock); > - mutex_unlock(&kvm->slots_lock); > + guard(mutex)(&kvm->slots_lock); > + guard(mutex)(&kvm->arch.config_lock); > > - return ret; > + if (!pkvm_hyp_vm_is_created(kvm)) > + return __pkvm_create_hyp_vm(kvm); > + > + return 0; > } > > int pkvm_create_hyp_vcpu(struct kvm_vcpu *vcpu) > { > - int ret = 0; > + guard(mutex)(&vcpu->kvm->arch.config_lock); > > - mutex_lock(&vcpu->kvm->arch.config_lock); > if (!vcpu_get_flag(vcpu, VCPU_PKVM_FINALIZED)) > - ret = __pkvm_create_hyp_vcpu(vcpu); > - mutex_unlock(&vcpu->kvm->arch.config_lock); > + return __pkvm_create_hyp_vcpu(vcpu); > > - return ret; > + return 0; > } > > void pkvm_destroy_hyp_vm(struct kvm *kvm) > { > - mutex_lock(&kvm->arch.config_lock); > + guard(mutex)(&kvm->arch.config_lock); > __pkvm_destroy_hyp_vm(kvm); > - mutex_unlock(&kvm->arch.config_lock); > } > > int pkvm_init_host_vm(struct kvm *kvm, unsigned long type) > diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c > index 3b5dbe9a0a0e..e1389c525e9d 100644 > --- a/arch/arm64/kvm/psci.c > +++ b/arch/arm64/kvm/psci.c > @@ -62,7 +62,6 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu) > struct vcpu_reset_state *reset_state; > struct kvm *kvm = source_vcpu->kvm; > struct kvm_vcpu *vcpu = NULL; > - int ret = PSCI_RET_SUCCESS; > unsigned long cpu_id; > > cpu_id = smccc_get_arg1(source_vcpu); > @@ -78,14 +77,13 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu) > if (!vcpu) > return PSCI_RET_INVALID_PARAMS; > > - spin_lock(&vcpu->arch.mp_state_lock); > + guard(spinlock)(&vcpu->arch.mp_state_lock); > + > if (!kvm_arm_vcpu_stopped(vcpu)) { > if (kvm_psci_version(source_vcpu) != KVM_ARM_PSCI_0_1) > - ret = PSCI_RET_ALREADY_ON; > + return PSCI_RET_ALREADY_ON; > else > - ret = PSCI_RET_INVALID_PARAMS; > - > - goto out_unlock; > + return PSCI_RET_INVALID_PARAMS; > } > > reset_state = &vcpu->arch.reset_state; > @@ -113,9 +111,7 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu) > WRITE_ONCE(vcpu->arch.mp_state.mp_state, KVM_MP_STATE_RUNNABLE); > kvm_vcpu_wake_up(vcpu); > > -out_unlock: > - spin_unlock(&vcpu->arch.mp_state_lock); > - return ret; > + return PSCI_RET_SUCCESS; > } > > static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu) > @@ -176,9 +172,8 @@ static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type, u64 flags) > * re-initialized. > */ > kvm_for_each_vcpu(i, tmp, vcpu->kvm) { > - spin_lock(&tmp->arch.mp_state_lock); > + guard(spinlock)(&tmp->arch.mp_state_lock); > WRITE_ONCE(tmp->arch.mp_state.mp_state, KVM_MP_STATE_STOPPED); > - spin_unlock(&tmp->arch.mp_state_lock); > } > kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_SLEEP); > > diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c > index b963fd975aac..60969d90bdd3 100644 > --- a/arch/arm64/kvm/reset.c > +++ b/arch/arm64/kvm/reset.c > @@ -193,10 +193,10 @@ void kvm_reset_vcpu(struct kvm_vcpu *vcpu) > bool loaded; > u32 pstate; > > - spin_lock(&vcpu->arch.mp_state_lock); > - reset_state = vcpu->arch.reset_state; > - vcpu->arch.reset_state.reset = false; > - spin_unlock(&vcpu->arch.mp_state_lock); > + scoped_guard(spinlock, &vcpu->arch.mp_state_lock) { > + reset_state = vcpu->arch.reset_state; > + vcpu->arch.reset_state.reset = false; > + } Same, I don't find this one really interesting. > > preempt_disable(); > loaded = (vcpu->cpu != -1); > -- > 2.54.0.1136.gdb2ca164c4-goog >