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Subject[PATCH] KVM: MMU: propagate alloc_workqueue failure
Date
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.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
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);
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;
+ return 1;
}

/* 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;
+
+ 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
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