KVM: x86: Gracefully handle __vmalloc() failure during VM allocation

[platform/kernel/linux-rpi.git] / arch / x86 / kvm / vmx / vmx.c

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4d5c83a..e0d16ba 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -648,43 +648,15 @@ void loaded_vmcs_init(struct loaded_vmcs *loaded_vmcs)
 }
 
 #ifdef CONFIG_KEXEC_CORE
-/*
- * This bitmap is used to indicate whether the vmclear
- * operation is enabled on all cpus. All disabled by
- * default.
- */
-static cpumask_t crash_vmclear_enabled_bitmap = CPU_MASK_NONE;
-
-static inline void crash_enable_local_vmclear(int cpu)
-{
-       cpumask_set_cpu(cpu, &crash_vmclear_enabled_bitmap);
-}
-
-static inline void crash_disable_local_vmclear(int cpu)
-{
-       cpumask_clear_cpu(cpu, &crash_vmclear_enabled_bitmap);
-}
-
-static inline int crash_local_vmclear_enabled(int cpu)
-{
-       return cpumask_test_cpu(cpu, &crash_vmclear_enabled_bitmap);
-}
-
 static void crash_vmclear_local_loaded_vmcss(void)
 {
        int cpu = raw_smp_processor_id();
        struct loaded_vmcs *v;
 
-       if (!crash_local_vmclear_enabled(cpu))
-               return;
-
        list_for_each_entry(v, &per_cpu(loaded_vmcss_on_cpu, cpu),
                            loaded_vmcss_on_cpu_link)
                vmcs_clear(v->vmcs);
 }
-#else
-static inline void crash_enable_local_vmclear(int cpu) { }
-static inline void crash_disable_local_vmclear(int cpu) { }
 #endif /* CONFIG_KEXEC_CORE */
 
 static void __loaded_vmcs_clear(void *arg)
@@ -696,19 +668,24 @@ static void __loaded_vmcs_clear(void *arg)
                return; /* vcpu migration can race with cpu offline */
        if (per_cpu(current_vmcs, cpu) == loaded_vmcs->vmcs)
                per_cpu(current_vmcs, cpu) = NULL;
-       crash_disable_local_vmclear(cpu);
+
+       vmcs_clear(loaded_vmcs->vmcs);
+       if (loaded_vmcs->shadow_vmcs && loaded_vmcs->launched)
+               vmcs_clear(loaded_vmcs->shadow_vmcs);
+
        list_del(&loaded_vmcs->loaded_vmcss_on_cpu_link);
 
        /*
-        * we should ensure updating loaded_vmcs->loaded_vmcss_on_cpu_link
-        * is before setting loaded_vmcs->vcpu to -1 which is done in
-        * loaded_vmcs_init. Otherwise, other cpu can see vcpu = -1 fist
-        * then adds the vmcs into percpu list before it is deleted.
+        * Ensure all writes to loaded_vmcs, including deleting it from its
+        * current percpu list, complete before setting loaded_vmcs->vcpu to
+        * -1, otherwise a different cpu can see vcpu == -1 first and add
+        * loaded_vmcs to its percpu list before it's deleted from this cpu's
+        * list. Pairs with the smp_rmb() in vmx_vcpu_load_vmcs().
         */
        smp_wmb();
 
-       loaded_vmcs_init(loaded_vmcs);
-       crash_enable_local_vmclear(cpu);
+       loaded_vmcs->cpu = -1;
+       loaded_vmcs->launched = 0;
 }
 
 void loaded_vmcs_clear(struct loaded_vmcs *loaded_vmcs)
@@ -1317,18 +1294,17 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu)
        if (!already_loaded) {
                loaded_vmcs_clear(vmx->loaded_vmcs);
                local_irq_disable();
-               crash_disable_local_vmclear(cpu);
 
                /*
-                * Read loaded_vmcs->cpu should be before fetching
-                * loaded_vmcs->loaded_vmcss_on_cpu_link.
-                * See the comments in __loaded_vmcs_clear().
+                * Ensure loaded_vmcs->cpu is read before adding loaded_vmcs to
+                * this cpu's percpu list, otherwise it may not yet be deleted
+                * from its previous cpu's percpu list.  Pairs with the
+                * smb_wmb() in __loaded_vmcs_clear().
                 */
                smp_rmb();
 
                list_add(&vmx->loaded_vmcs->loaded_vmcss_on_cpu_link,
                         &per_cpu(loaded_vmcss_on_cpu, cpu));
-               crash_enable_local_vmclear(cpu);
                local_irq_enable();
        }
 
@@ -2256,17 +2232,6 @@ static int hardware_enable(void)
        INIT_LIST_HEAD(&per_cpu(blocked_vcpu_on_cpu, cpu));
        spin_lock_init(&per_cpu(blocked_vcpu_on_cpu_lock, cpu));
 
-       /*
-        * Now we can enable the vmclear operation in kdump
-        * since the loaded_vmcss_on_cpu list on this cpu
-        * has been initialized.
-        *
-        * Though the cpu is not in VMX operation now, there
-        * is no problem to enable the vmclear operation
-        * for the loaded_vmcss_on_cpu list is empty!
-        */
-       crash_enable_local_vmclear(cpu);
-
        rdmsrl(MSR_IA32_FEATURE_CONTROL, old);
 
        test_bits = FEATURE_CONTROL_LOCKED;
@@ -6689,6 +6654,10 @@ static struct kvm *vmx_vm_alloc(void)
        struct kvm_vmx *kvm_vmx = __vmalloc(sizeof(struct kvm_vmx),
                                            GFP_KERNEL_ACCOUNT | __GFP_ZERO,
                                            PAGE_KERNEL);
+
+       if (!kvm_vmx)
+               return NULL;
+
        return &kvm_vmx->kvm;
 }