From 0d4ee88d92884c661fcafd5576da243aa943dc24 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Thu, 23 May 2019 16:35:34 +1000 Subject: KVM: PPC: Book3S HV: Use new mutex to synchronize MMU setup Currently the HV KVM code uses kvm->lock in conjunction with a flag, kvm->arch.mmu_ready, to synchronize MMU setup and hold off vcpu execution until the MMU-related data structures are ready. However, this means that kvm->lock is being taken inside vcpu->mutex, which is contrary to Documentation/virtual/kvm/locking.txt and results in lockdep warnings. To fix this, we add a new mutex, kvm->arch.mmu_setup_lock, which nests inside the vcpu mutexes, and is taken in the places where kvm->lock was taken that are related to MMU setup. Additionally we take the new mutex in the vcpu creation code at the point where we are creating a new vcore, in order to provide mutual exclusion with kvmppc_update_lpcr() and ensure that an update to kvm->arch.lpcr doesn't get missed, which could otherwise lead to a stale vcore->lpcr value. Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_64_mmu_hv.c | 36 ++++++++++++++++++------------------ arch/powerpc/kvm/book3s_hv.c | 31 +++++++++++++++++++++++-------- 2 files changed, 41 insertions(+), 26 deletions(-) (limited to 'arch/powerpc/kvm') diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index ab3d484c5e2e..51971311e6c9 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -63,7 +63,7 @@ struct kvm_resize_hpt { struct work_struct work; u32 order; - /* These fields protected by kvm->lock */ + /* These fields protected by kvm->arch.mmu_setup_lock */ /* Possible values and their usage: * <0 an error occurred during allocation, @@ -73,7 +73,7 @@ struct kvm_resize_hpt { int error; /* Private to the work thread, until error != -EBUSY, - * then protected by kvm->lock. + * then protected by kvm->arch.mmu_setup_lock. */ struct kvm_hpt_info hpt; }; @@ -139,7 +139,7 @@ long kvmppc_alloc_reset_hpt(struct kvm *kvm, int order) long err = -EBUSY; struct kvm_hpt_info info; - mutex_lock(&kvm->lock); + mutex_lock(&kvm->arch.mmu_setup_lock); if (kvm->arch.mmu_ready) { kvm->arch.mmu_ready = 0; /* order mmu_ready vs. vcpus_running */ @@ -183,7 +183,7 @@ out: /* Ensure that each vcpu will flush its TLB on next entry. */ cpumask_setall(&kvm->arch.need_tlb_flush); - mutex_unlock(&kvm->lock); + mutex_unlock(&kvm->arch.mmu_setup_lock); return err; } @@ -1447,7 +1447,7 @@ static void resize_hpt_pivot(struct kvm_resize_hpt *resize) static void resize_hpt_release(struct kvm *kvm, struct kvm_resize_hpt *resize) { - if (WARN_ON(!mutex_is_locked(&kvm->lock))) + if (WARN_ON(!mutex_is_locked(&kvm->arch.mmu_setup_lock))) return; if (!resize) @@ -1474,14 +1474,14 @@ static void resize_hpt_prepare_work(struct work_struct *work) if (WARN_ON(resize->error != -EBUSY)) return; - mutex_lock(&kvm->lock); + mutex_lock(&kvm->arch.mmu_setup_lock); /* Request is still current? */ if (kvm->arch.resize_hpt == resize) { /* We may request large allocations here: - * do not sleep with kvm->lock held for a while. + * do not sleep with kvm->arch.mmu_setup_lock held for a while. */ - mutex_unlock(&kvm->lock); + mutex_unlock(&kvm->arch.mmu_setup_lock); resize_hpt_debug(resize, "resize_hpt_prepare_work(): order = %d\n", resize->order); @@ -1494,9 +1494,9 @@ static void resize_hpt_prepare_work(struct work_struct *work) if (WARN_ON(err == -EBUSY)) err = -EINPROGRESS; - mutex_lock(&kvm->lock); + mutex_lock(&kvm->arch.mmu_setup_lock); /* It is possible that kvm->arch.resize_hpt != resize - * after we grab kvm->lock again. + * after we grab kvm->arch.mmu_setup_lock again. */ } @@ -1505,7 +1505,7 @@ static void resize_hpt_prepare_work(struct work_struct *work) if (kvm->arch.resize_hpt != resize) resize_hpt_release(kvm, resize); - mutex_unlock(&kvm->lock); + mutex_unlock(&kvm->arch.mmu_setup_lock); } long kvm_vm_ioctl_resize_hpt_prepare(struct kvm *kvm, @@ -1522,7 +1522,7 @@ long kvm_vm_ioctl_resize_hpt_prepare(struct kvm *kvm, if (shift && ((shift < 18) || (shift > 46))) return -EINVAL; - mutex_lock(&kvm->lock); + mutex_lock(&kvm->arch.mmu_setup_lock); resize = kvm->arch.resize_hpt; @@ -1565,7 +1565,7 @@ long kvm_vm_ioctl_resize_hpt_prepare(struct kvm *kvm, ret = 100; /* estimated time in ms */ out: - mutex_unlock(&kvm->lock); + mutex_unlock(&kvm->arch.mmu_setup_lock); return ret; } @@ -1588,7 +1588,7 @@ long kvm_vm_ioctl_resize_hpt_commit(struct kvm *kvm, if (shift && ((shift < 18) || (shift > 46))) return -EINVAL; - mutex_lock(&kvm->lock); + mutex_lock(&kvm->arch.mmu_setup_lock); resize = kvm->arch.resize_hpt; @@ -1625,7 +1625,7 @@ out: smp_mb(); out_no_hpt: resize_hpt_release(kvm, resize); - mutex_unlock(&kvm->lock); + mutex_unlock(&kvm->arch.mmu_setup_lock); return ret; } @@ -1868,7 +1868,7 @@ static ssize_t kvm_htab_write(struct file *file, const char __user *buf, return -EINVAL; /* lock out vcpus from running while we're doing this */ - mutex_lock(&kvm->lock); + mutex_lock(&kvm->arch.mmu_setup_lock); mmu_ready = kvm->arch.mmu_ready; if (mmu_ready) { kvm->arch.mmu_ready = 0; /* temporarily */ @@ -1876,7 +1876,7 @@ static ssize_t kvm_htab_write(struct file *file, const char __user *buf, smp_mb(); if (atomic_read(&kvm->arch.vcpus_running)) { kvm->arch.mmu_ready = 1; - mutex_unlock(&kvm->lock); + mutex_unlock(&kvm->arch.mmu_setup_lock); return -EBUSY; } } @@ -1963,7 +1963,7 @@ static ssize_t kvm_htab_write(struct file *file, const char __user *buf, /* Order HPTE updates vs. mmu_ready */ smp_wmb(); kvm->arch.mmu_ready = mmu_ready; - mutex_unlock(&kvm->lock); + mutex_unlock(&kvm->arch.mmu_setup_lock); if (err) return err; diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index d5fc624e0655..b1c0a9bc3555 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -2338,11 +2338,17 @@ static struct kvm_vcpu *kvmppc_core_vcpu_create_hv(struct kvm *kvm, pr_devel("KVM: collision on id %u", id); vcore = NULL; } else if (!vcore) { + /* + * Take mmu_setup_lock for mutual exclusion + * with kvmppc_update_lpcr(). + */ err = -ENOMEM; vcore = kvmppc_vcore_create(kvm, id & ~(kvm->arch.smt_mode - 1)); + mutex_lock(&kvm->arch.mmu_setup_lock); kvm->arch.vcores[core] = vcore; kvm->arch.online_vcores++; + mutex_unlock(&kvm->arch.mmu_setup_lock); } } mutex_unlock(&kvm->lock); @@ -3859,7 +3865,7 @@ static int kvmhv_setup_mmu(struct kvm_vcpu *vcpu) int r = 0; struct kvm *kvm = vcpu->kvm; - mutex_lock(&kvm->lock); + mutex_lock(&kvm->arch.mmu_setup_lock); if (!kvm->arch.mmu_ready) { if (!kvm_is_radix(kvm)) r = kvmppc_hv_setup_htab_rma(vcpu); @@ -3869,7 +3875,7 @@ static int kvmhv_setup_mmu(struct kvm_vcpu *vcpu) kvm->arch.mmu_ready = 1; } } - mutex_unlock(&kvm->lock); + mutex_unlock(&kvm->arch.mmu_setup_lock); return r; } @@ -4478,7 +4484,8 @@ static void kvmppc_core_commit_memory_region_hv(struct kvm *kvm, /* * Update LPCR values in kvm->arch and in vcores. - * Caller must hold kvm->lock. + * Caller must hold kvm->arch.mmu_setup_lock (for mutual exclusion + * of kvm->arch.lpcr update). */ void kvmppc_update_lpcr(struct kvm *kvm, unsigned long lpcr, unsigned long mask) { @@ -4530,7 +4537,7 @@ void kvmppc_setup_partition_table(struct kvm *kvm) /* * Set up HPT (hashed page table) and RMA (real-mode area). - * Must be called with kvm->lock held. + * Must be called with kvm->arch.mmu_setup_lock held. */ static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu) { @@ -4618,7 +4625,10 @@ static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu) goto out_srcu; } -/* Must be called with kvm->lock held and mmu_ready = 0 and no vcpus running */ +/* + * Must be called with kvm->arch.mmu_setup_lock held and + * mmu_ready = 0 and no vcpus running. + */ int kvmppc_switch_mmu_to_hpt(struct kvm *kvm) { if (nesting_enabled(kvm)) @@ -4635,7 +4645,10 @@ int kvmppc_switch_mmu_to_hpt(struct kvm *kvm) return 0; } -/* Must be called with kvm->lock held and mmu_ready = 0 and no vcpus running */ +/* + * Must be called with kvm->arch.mmu_setup_lock held and + * mmu_ready = 0 and no vcpus running. + */ int kvmppc_switch_mmu_to_radix(struct kvm *kvm) { int err; @@ -4740,6 +4753,8 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm) char buf[32]; int ret; + mutex_init(&kvm->arch.mmu_setup_lock); + /* Allocate the guest's logical partition ID */ lpid = kvmppc_alloc_lpid(); @@ -5265,7 +5280,7 @@ static int kvmhv_configure_mmu(struct kvm *kvm, struct kvm_ppc_mmuv3_cfg *cfg) if (kvmhv_on_pseries() && !radix) return -EINVAL; - mutex_lock(&kvm->lock); + mutex_lock(&kvm->arch.mmu_setup_lock); if (radix != kvm_is_radix(kvm)) { if (kvm->arch.mmu_ready) { kvm->arch.mmu_ready = 0; @@ -5293,7 +5308,7 @@ static int kvmhv_configure_mmu(struct kvm *kvm, struct kvm_ppc_mmuv3_cfg *cfg) err = 0; out_unlock: - mutex_unlock(&kvm->lock); + mutex_unlock(&kvm->arch.mmu_setup_lock); return err; } -- cgit v1.2.3