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[34.82.80.254]) by smtp.gmail.com with ESMTPSA id q9-20020a056a00088900b004e03b051040sm26642967pfj.112.2022.03.30.16.51.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Mar 2022 16:51:04 -0700 (PDT) Date: Wed, 30 Mar 2022 23:51:00 +0000 From: David Matlack To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH] KVM: MMU: propagate alloc_workqueue failure Message-ID: References: <20220330165510.213111-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220330165510.213111-1-pbonzini@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 30, 2022 at 12:55:10PM -0400, Paolo Bonzini wrote: > If kvm->arch.tdp_mmu_zap_wq cannot be created, the failure has > to be propagated up to kvm_mmu_init_vm and kvm_arch_init_vm. > kvm_arch_init_vm also has to undo all the initialization, so > group all the MMU initialization code at the beginning and > handle cleaning up of kvm_page_track_init. > Fixes: 22b94c4b63eb ("KVM: x86/mmu: Zap invalidated roots via asynchronous worker") > Signed-off-by: Paolo Bonzini > --- > arch/x86/include/asm/kvm_host.h | 2 +- > arch/x86/kvm/mmu/mmu.c | 11 +++++++++-- > arch/x86/kvm/mmu/tdp_mmu.c | 17 ++++++++++------- > arch/x86/kvm/mmu/tdp_mmu.h | 4 ++-- > arch/x86/kvm/x86.c | 15 ++++++++++----- > 5 files changed, 32 insertions(+), 17 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 0ddc2e67a731..469c7702fad9 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1584,7 +1584,7 @@ void kvm_mmu_module_exit(void); > > void kvm_mmu_destroy(struct kvm_vcpu *vcpu); > int kvm_mmu_create(struct kvm_vcpu *vcpu); > -void kvm_mmu_init_vm(struct kvm *kvm); > +int kvm_mmu_init_vm(struct kvm *kvm); > void kvm_mmu_uninit_vm(struct kvm *kvm); > > void kvm_mmu_after_set_cpuid(struct kvm_vcpu *vcpu); > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 51671cb34fb6..857ba93b5c92 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -5768,17 +5768,24 @@ static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm, > kvm_mmu_zap_all_fast(kvm); > } > > -void kvm_mmu_init_vm(struct kvm *kvm) > +int kvm_mmu_init_vm(struct kvm *kvm) > { > struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker; > + int r; > > + INIT_LIST_HEAD(&kvm->arch.active_mmu_pages); > + INIT_LIST_HEAD(&kvm->arch.zapped_obsolete_pages); > + INIT_LIST_HEAD(&kvm->arch.lpage_disallowed_mmu_pages); I agree with moving these but that should probably be done in a separate commit. > spin_lock_init(&kvm->arch.mmu_unsync_pages_lock); > > - kvm_mmu_init_tdp_mmu(kvm); > + r = kvm_mmu_init_tdp_mmu(kvm); > + if (r < 0) > + return r; > > node->track_write = kvm_mmu_pte_write; > node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot; > kvm_page_track_register_notifier(kvm, node); > + return 0; > } > > void kvm_mmu_uninit_vm(struct kvm *kvm) > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index e7e7876251b3..d7c112a29fe9 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -14,21 +14,24 @@ static bool __read_mostly tdp_mmu_enabled = true; > module_param_named(tdp_mmu, tdp_mmu_enabled, bool, 0644); > > /* Initializes the TDP MMU for the VM, if enabled. */ > -bool kvm_mmu_init_tdp_mmu(struct kvm *kvm) > +int kvm_mmu_init_tdp_mmu(struct kvm *kvm) > { > + struct workqueue_struct *wq; > + > if (!tdp_enabled || !READ_ONCE(tdp_mmu_enabled)) > - return false; > + return 0; > + > + wq = alloc_workqueue("kvm", WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 0); > + if (IS_ERR(wq)) > + return PTR_ERR(wq); > > /* This should not be changed for the lifetime of the VM. */ > kvm->arch.tdp_mmu_enabled = true; > - > INIT_LIST_HEAD(&kvm->arch.tdp_mmu_roots); > spin_lock_init(&kvm->arch.tdp_mmu_pages_lock); > INIT_LIST_HEAD(&kvm->arch.tdp_mmu_pages); > - kvm->arch.tdp_mmu_zap_wq = > - alloc_workqueue("kvm", WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 0); > - > - return true; > + kvm->arch.tdp_mmu_zap_wq = wq; Suggest moving this to just after checking the return value of alloc_workqueue(). > + return 1; Perhaps return 0 until we have a reason to differentiate the 2 cases. > } > > /* Arbitrarily returns true so that this may be used in if statements. */ > diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h > index 5e5ef2576c81..647926541e38 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.h > +++ b/arch/x86/kvm/mmu/tdp_mmu.h > @@ -72,7 +72,7 @@ u64 *kvm_tdp_mmu_fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, u64 addr, > u64 *spte); > > #ifdef CONFIG_X86_64 > -bool kvm_mmu_init_tdp_mmu(struct kvm *kvm); > +int kvm_mmu_init_tdp_mmu(struct kvm *kvm); > void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm); > static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp) { return sp->tdp_mmu_page; } > > @@ -93,7 +93,7 @@ static inline bool is_tdp_mmu(struct kvm_mmu *mmu) > return sp && is_tdp_mmu_page(sp) && sp->root_count; > } > #else > -static inline bool kvm_mmu_init_tdp_mmu(struct kvm *kvm) { return false; } > +static inline int kvm_mmu_init_tdp_mmu(struct kvm *kvm) { return 0; } > static inline void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm) {} > static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp) { return false; } > static inline bool is_tdp_mmu(struct kvm_mmu *mmu) { return false; } > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index fe2171b11441..89b6efb7f504 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -11629,12 +11629,13 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) > > ret = kvm_page_track_init(kvm); > if (ret) > - return ret; > + goto out; nit: This goto is unnecessary. > + > + ret = kvm_mmu_init_vm(kvm); > + if (ret) > + goto out_page_track; > > INIT_HLIST_HEAD(&kvm->arch.mask_notifier_list); > - INIT_LIST_HEAD(&kvm->arch.active_mmu_pages); > - INIT_LIST_HEAD(&kvm->arch.zapped_obsolete_pages); > - INIT_LIST_HEAD(&kvm->arch.lpage_disallowed_mmu_pages); > INIT_LIST_HEAD(&kvm->arch.assigned_dev_head); > atomic_set(&kvm->arch.noncoherent_dma_count, 0); > > @@ -11666,10 +11667,14 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) > > kvm_apicv_init(kvm); > kvm_hv_init_vm(kvm); > - kvm_mmu_init_vm(kvm); > kvm_xen_init_vm(kvm); > > return static_call(kvm_x86_vm_init)(kvm); > + > +out_page_track: > + kvm_page_track_cleanup(kvm); > +out: > + return ret; > } > > int kvm_arch_post_init_vm(struct kvm *kvm) > -- > 2.31.1 >