From 0e4524a5d341e719e8ee9ee7db5d58e2c5a4c10e Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Thu, 6 Jul 2017 14:44:28 +0200 Subject: KVM: mark vcpu->pid pointer as rcu protected We do use rcu to protect the pid pointer. Mark it as such and adopt all code to use the proper access methods. This was detected by sparse. "virt/kvm/kvm_main.c:2248:15: error: incompatible types in comparison expression (different address spaces)" Signed-off-by: Christian Borntraeger Reviewed-by: Paolo Bonzini --- virt/kvm/kvm_main.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) (limited to 'virt/kvm') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 19f0ecb9b93e..fc2d58312fd5 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -293,7 +293,12 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_init); void kvm_vcpu_uninit(struct kvm_vcpu *vcpu) { - put_pid(vcpu->pid); + /* + * no need for rcu_read_lock as VCPU_RUN is the only place that + * will change the vcpu->pid pointer and on uninit all file + * descriptors are already gone. + */ + put_pid(rcu_dereference_protected(vcpu->pid, 1)); kvm_arch_vcpu_uninit(vcpu); free_page((unsigned long)vcpu->run); } @@ -2551,13 +2556,14 @@ static long kvm_vcpu_ioctl(struct file *filp, if (r) return r; switch (ioctl) { - case KVM_RUN: + case KVM_RUN: { + struct pid *oldpid; r = -EINVAL; if (arg) goto out; - if (unlikely(vcpu->pid != current->pids[PIDTYPE_PID].pid)) { + oldpid = rcu_access_pointer(vcpu->pid); + if (unlikely(oldpid != current->pids[PIDTYPE_PID].pid)) { /* The thread running this VCPU changed. */ - struct pid *oldpid = vcpu->pid; struct pid *newpid = get_task_pid(current, PIDTYPE_PID); rcu_assign_pointer(vcpu->pid, newpid); @@ -2568,6 +2574,7 @@ static long kvm_vcpu_ioctl(struct file *filp, r = kvm_arch_vcpu_ioctl_run(vcpu, vcpu->run); trace_kvm_userspace_exit(vcpu->run->exit_reason, r); break; + } case KVM_GET_REGS: { struct kvm_regs *kvm_regs; -- cgit v1.2.3 From 5535f800b0e1533e5f3a1428f6ef25eb29eccc0f Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Thu, 6 Jul 2017 20:31:11 +0200 Subject: KVM: use rcu access function for irq routing irq routing is rcu protected. Use the proper access functions. Found by sparse virt/kvm/irqchip.c:233:13: warning: incorrect type in assignment (different address spaces) virt/kvm/irqchip.c:233:13: expected struct kvm_irq_routing_table *old virt/kvm/irqchip.c:233:13: got struct kvm_irq_routing_table [noderef] *irq_routing Signed-off-by: Christian Borntraeger Reviewed-by: Paolo Bonzini --- virt/kvm/irqchip.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'virt/kvm') diff --git a/virt/kvm/irqchip.c b/virt/kvm/irqchip.c index 31e40c9e81df..b1286c4e0712 100644 --- a/virt/kvm/irqchip.c +++ b/virt/kvm/irqchip.c @@ -230,7 +230,7 @@ int kvm_set_irq_routing(struct kvm *kvm, } mutex_lock(&kvm->irq_lock); - old = kvm->irq_routing; + old = rcu_dereference_protected(kvm->irq_routing, 1); rcu_assign_pointer(kvm->irq_routing, new); kvm_irq_routing_update(kvm); kvm_arch_irq_routing_update(kvm); -- cgit v1.2.3 From 4a12f95177280a660bda99e81838919b1cc6a91a Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Fri, 7 Jul 2017 10:51:38 +0200 Subject: KVM: mark kvm->busses as rcu protected mark kvm->busses as rcu protected and use the correct access function everywhere. found by sparse virt/kvm/kvm_main.c:3490:15: error: incompatible types in comparison expression (different address spaces) virt/kvm/kvm_main.c:3509:15: error: incompatible types in comparison expression (different address spaces) virt/kvm/kvm_main.c:3561:15: error: incompatible types in comparison expression (different address spaces) virt/kvm/kvm_main.c:3644:15: error: incompatible types in comparison expression (different address spaces) Signed-off-by: Christian Borntraeger --- include/linux/kvm_host.h | 8 +++++++- virt/kvm/eventfd.c | 8 +++++--- virt/kvm/kvm_main.c | 17 ++++++++++------- 3 files changed, 22 insertions(+), 11 deletions(-) (limited to 'virt/kvm') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index bcd37b855c66..6a164f9eb02c 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -404,7 +404,7 @@ struct kvm { int last_boosted_vcpu; struct list_head vm_list; struct mutex lock; - struct kvm_io_bus *buses[KVM_NR_BUSES]; + struct kvm_io_bus __rcu *buses[KVM_NR_BUSES]; #ifdef CONFIG_HAVE_KVM_EVENTFD struct { spinlock_t lock; @@ -473,6 +473,12 @@ struct kvm { #define vcpu_err(vcpu, fmt, ...) \ kvm_err("vcpu%i " fmt, (vcpu)->vcpu_id, ## __VA_ARGS__) +static inline struct kvm_io_bus *kvm_get_bus(struct kvm *kvm, enum kvm_bus idx) +{ + return srcu_dereference_check(kvm->buses[idx], &kvm->srcu, + lockdep_is_held(&kvm->slots_lock)); +} + static inline struct kvm_vcpu *kvm_get_vcpu(struct kvm *kvm, int i) { /* Pairs with smp_wmb() in kvm_vm_ioctl_create_vcpu, in case diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index a8d540398bbd..d016aadd5fbb 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -825,7 +825,7 @@ static int kvm_assign_ioeventfd_idx(struct kvm *kvm, if (ret < 0) goto unlock_fail; - kvm->buses[bus_idx]->ioeventfd_count++; + kvm_get_bus(kvm, bus_idx)->ioeventfd_count++; list_add_tail(&p->list, &kvm->ioeventfds); mutex_unlock(&kvm->slots_lock); @@ -848,6 +848,7 @@ kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx, { struct _ioeventfd *p, *tmp; struct eventfd_ctx *eventfd; + struct kvm_io_bus *bus; int ret = -ENOENT; eventfd = eventfd_ctx_fdget(args->fd); @@ -870,8 +871,9 @@ kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx, continue; kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev); - if (kvm->buses[bus_idx]) - kvm->buses[bus_idx]->ioeventfd_count--; + bus = kvm_get_bus(kvm, bus_idx); + if (bus) + bus->ioeventfd_count--; ioeventfd_release(p); ret = 0; break; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index fc2d58312fd5..d76e822f8929 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -679,8 +679,8 @@ static struct kvm *kvm_create_vm(unsigned long type) if (init_srcu_struct(&kvm->irq_srcu)) goto out_err_no_irq_srcu; for (i = 0; i < KVM_NR_BUSES; i++) { - kvm->buses[i] = kzalloc(sizeof(struct kvm_io_bus), - GFP_KERNEL); + rcu_assign_pointer(kvm->buses[i], + kzalloc(sizeof(struct kvm_io_bus), GFP_KERNEL)); if (!kvm->buses[i]) goto out_err; } @@ -705,7 +705,7 @@ out_err_no_srcu: hardware_disable_all(); out_err_no_disable: for (i = 0; i < KVM_NR_BUSES; i++) - kfree(kvm->buses[i]); + kfree(rcu_access_pointer(kvm->buses[i])); for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) kvm_free_memslots(kvm, kvm->memslots[i]); kvm_arch_free_vm(kvm); @@ -740,8 +740,11 @@ static void kvm_destroy_vm(struct kvm *kvm) spin_unlock(&kvm_lock); kvm_free_irq_routing(kvm); for (i = 0; i < KVM_NR_BUSES; i++) { - if (kvm->buses[i]) - kvm_io_bus_destroy(kvm->buses[i]); + struct kvm_io_bus *bus; + + bus = rcu_dereference_protected(kvm->buses[i], 1); + if (bus) + kvm_io_bus_destroy(bus); kvm->buses[i] = NULL; } kvm_coalesced_mmio_free(kvm); @@ -3570,7 +3573,7 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, { struct kvm_io_bus *new_bus, *bus; - bus = kvm->buses[bus_idx]; + bus = kvm_get_bus(kvm, bus_idx); if (!bus) return -ENOMEM; @@ -3599,7 +3602,7 @@ void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, int i; struct kvm_io_bus *new_bus, *bus; - bus = kvm->buses[bus_idx]; + bus = kvm_get_bus(kvm, bus_idx); if (!bus) return; -- cgit v1.2.3 From a80cf7b5f4149753d5f19c872a47e66195b167d4 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Thu, 6 Jul 2017 16:17:14 +0200 Subject: KVM: mark memory slots as rcu we access the memslots array via srcu. Mark it as such and use the right access functions also for the freeing of memory slots. Found by sparse: ./include/linux/kvm_host.h:565:16: error: incompatible types in comparison expression (different address spaces) Signed-off-by: Christian Borntraeger Reviewed-by: Paolo Bonzini --- include/linux/kvm_host.h | 2 +- virt/kvm/kvm_main.c | 6 ++++-- 2 files changed, 5 insertions(+), 3 deletions(-) (limited to 'virt/kvm') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 6a164f9eb02c..b3ca77a96b2d 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -390,7 +390,7 @@ struct kvm { spinlock_t mmu_lock; struct mutex slots_lock; struct mm_struct *mm; /* userspace tied to this vm */ - struct kvm_memslots *memslots[KVM_ADDRESS_SPACE_NUM]; + struct kvm_memslots __rcu *memslots[KVM_ADDRESS_SPACE_NUM]; struct kvm_vcpu *vcpus[KVM_MAX_VCPUS]; /* diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index d76e822f8929..6e6d4edf0e92 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -707,7 +707,8 @@ out_err_no_disable: for (i = 0; i < KVM_NR_BUSES; i++) kfree(rcu_access_pointer(kvm->buses[i])); for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) - kvm_free_memslots(kvm, kvm->memslots[i]); + kvm_free_memslots(kvm, + rcu_dereference_protected(kvm->memslots[i], 1)); kvm_arch_free_vm(kvm); mmdrop(current->mm); return ERR_PTR(r); @@ -756,7 +757,8 @@ static void kvm_destroy_vm(struct kvm *kvm) kvm_arch_destroy_vm(kvm); kvm_destroy_devices(kvm); for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) - kvm_free_memslots(kvm, kvm->memslots[i]); + kvm_free_memslots(kvm, + rcu_dereference_protected(kvm->memslots[i], 1)); cleanup_srcu_struct(&kvm->irq_srcu); cleanup_srcu_struct(&kvm->srcu); kvm_arch_free_vm(kvm); -- cgit v1.2.3 From b49defe83659cefbb1763d541e779da32594ab10 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 30 Jun 2017 13:25:45 +0200 Subject: kvm: avoid unused variable warning for UP builds The uniprocessor version of smp_call_function_many does not evaluate all of its argument, and the compiler emits a warning about "wait" being unused. This breaks the build on architectures for which "-Werror" is enabled by default. Work around it by moving the invocation of smp_call_function_many to its own inline function. Reported-by: Paul Mackerras Cc: stable@vger.kernel.org Fixes: 7a97cec26b94c909f4cbad2dc3186af3e457a522 Signed-off-by: Paolo Bonzini --- virt/kvm/kvm_main.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) (limited to 'virt/kvm') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 19f0ecb9b93e..0d796c9a6482 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -187,12 +187,23 @@ static void ack_flush(void *_completed) { } +static inline bool kvm_kick_many_cpus(const struct cpumask *cpus, bool wait) +{ + if (unlikely(!cpus)) + cpus = cpu_online_mask; + + if (cpumask_empty(cpus)) + return false; + + smp_call_function_many(cpus, ack_flush, NULL, wait); + return true; +} + bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req) { int i, cpu, me; cpumask_var_t cpus; - bool called = true; - bool wait = req & KVM_REQUEST_WAIT; + bool called; struct kvm_vcpu *vcpu; zalloc_cpumask_var(&cpus, GFP_ATOMIC); @@ -207,14 +218,9 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req) if (cpus != NULL && cpu != -1 && cpu != me && kvm_request_needs_ipi(vcpu, req)) - cpumask_set_cpu(cpu, cpus); + __cpumask_set_cpu(cpu, cpus); } - if (unlikely(cpus == NULL)) - smp_call_function_many(cpu_online_mask, ack_flush, NULL, wait); - else if (!cpumask_empty(cpus)) - smp_call_function_many(cpus, ack_flush, NULL, wait); - else - called = false; + called = kvm_kick_many_cpus(cpus, !!(req & KVM_REQUEST_WAIT)); put_cpu(); free_cpumask_var(cpus); return called; -- cgit v1.2.3 From 286de8f6ac9202f1c9012784639156c6ec386eb8 Mon Sep 17 00:00:00 2001 From: Claudio Imbrenda Date: Wed, 12 Jul 2017 17:56:44 +0200 Subject: KVM: trigger uevents when creating or destroying a VM This patch adds a few lines to the KVM common code to fire a KOBJ_CHANGE uevent whenever a KVM VM is created or destroyed. The event carries five environment variables: CREATED indicates how many times a new VM has been created. It is useful for example to trigger specific actions when the first VM is started COUNT indicates how many VMs are currently active. This can be used for logging or monitoring purposes PID has the pid of the KVM process that has been started or stopped. This can be used to perform process-specific tuning. STATS_PATH contains the path in debugfs to the directory with all the runtime statistics for this VM. This is useful for performance monitoring and profiling. EVENT described the type of event, its value can be either "create" or "destroy" Specific udev rules can be then set up in userspace to deal with the creation or destruction of VMs as needed. Signed-off-by: Claudio Imbrenda Signed-off-by: Radim Krčmář --- virt/kvm/kvm_main.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) (limited to 'virt/kvm') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 7766c2b52797..82987d457b8b 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -130,6 +130,12 @@ EXPORT_SYMBOL_GPL(kvm_rebooting); static bool largepages_enabled = true; +#define KVM_EVENT_CREATE_VM 0 +#define KVM_EVENT_DESTROY_VM 1 +static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm); +static unsigned long long kvm_createvm_count; +static unsigned long long kvm_active_vms; + bool kvm_is_reserved_pfn(kvm_pfn_t pfn) { if (pfn_valid(pfn)) @@ -740,6 +746,7 @@ static void kvm_destroy_vm(struct kvm *kvm) int i; struct mm_struct *mm = kvm->mm; + kvm_uevent_notify_change(KVM_EVENT_DESTROY_VM, kvm); kvm_destroy_vm_debugfs(kvm); kvm_arch_sync_events(kvm); spin_lock(&kvm_lock); @@ -3220,6 +3227,7 @@ static int kvm_dev_ioctl_create_vm(unsigned long type) fput(file); return -ENOMEM; } + kvm_uevent_notify_change(KVM_EVENT_CREATE_VM, kvm); fd_install(r, file); return r; @@ -3872,6 +3880,67 @@ static const struct file_operations *stat_fops[] = { [KVM_STAT_VM] = &vm_stat_fops, }; +static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm) +{ + struct kobj_uevent_env *env; + char *tmp, *pathbuf = NULL; + unsigned long long created, active; + + if (!kvm_dev.this_device || !kvm) + return; + + spin_lock(&kvm_lock); + if (type == KVM_EVENT_CREATE_VM) { + kvm_createvm_count++; + kvm_active_vms++; + } else if (type == KVM_EVENT_DESTROY_VM) { + kvm_active_vms--; + } + created = kvm_createvm_count; + active = kvm_active_vms; + spin_unlock(&kvm_lock); + + env = kzalloc(sizeof(*env), GFP_KERNEL); + if (!env) + return; + + add_uevent_var(env, "CREATED=%llu", created); + add_uevent_var(env, "COUNT=%llu", active); + + if (type == KVM_EVENT_CREATE_VM) + add_uevent_var(env, "EVENT=create"); + else if (type == KVM_EVENT_DESTROY_VM) + add_uevent_var(env, "EVENT=destroy"); + + if (kvm->debugfs_dentry) { + char p[ITOA_MAX_LEN]; + + snprintf(p, sizeof(p), "%s", kvm->debugfs_dentry->d_name.name); + tmp = strchrnul(p + 1, '-'); + *tmp = '\0'; + add_uevent_var(env, "PID=%s", p); + pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); + if (pathbuf) { + /* sizeof counts the final '\0' */ + int len = sizeof("STATS_PATH=") - 1; + const char *pvar = "STATS_PATH="; + + tmp = dentry_path_raw(kvm->debugfs_dentry, + pathbuf + len, + PATH_MAX - len); + if (!IS_ERR(tmp)) { + memcpy(tmp - len, pvar, len); + env->envp[env->envp_idx++] = tmp - len; + } + } + } + /* no need for checks, since we are adding at most only 5 keys */ + env->envp[env->envp_idx++] = NULL; + kobject_uevent_env(&kvm_dev.this_device->kobj, KOBJ_CHANGE, env->envp); + kfree(env); + kfree(pathbuf); +} + static int kvm_init_debug(void) { int r = -EEXIST; -- cgit v1.2.3