Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
"x86 guest:

- Tweaks to the paravirtualization code, to avoid using them when
they're pointless or harmful

x86 host:

- Fix for SRCU lockdep splat

- Brown paper bag fix for the propagation of errno"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: pull kvm->srcu read-side to kvm_arch_vcpu_ioctl_run
KVM: x86/mmu: Passing up the error state of mmu_alloc_shadow_roots()
KVM: x86: Yield to IPI target vCPU only if it is busy
x86/kvmclock: Fix Hyper-V Isolated VM's boot issue when vCPUs > 64
x86/kvm: Don't waste memory if kvmclock is disabled
x86/kvm: Don't use PV TLB/yield when mwait is advertised

arch/x86/kernel/kvm.c

···
 	return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
 		!kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 		kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
+		!boot_cpu_has(X86_FEATURE_MWAIT) &&
 		(num_possible_cpus() != 1));
 }
 
···
 	return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
 		!kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 	    kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
+	    !boot_cpu_has(X86_FEATURE_MWAIT) &&
 	    (num_possible_cpus() != 1));
 }
 
···
 
 	/* Make sure other vCPUs get a chance to run if they need to. */
 	for_each_cpu(cpu, mask) {
-		if (vcpu_is_preempted(cpu)) {
+		if (!idle_cpu(cpu) && vcpu_is_preempted(cpu)) {
 			kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
 			break;
 		}

arch/x86/kernel/kvmclock.c

···
 
 static int __init kvm_setup_vsyscall_timeinfo(void)
 {
+	if (!kvm_para_available() || !kvmclock)
+		return 0;
+
 	kvmclock_init_mem();
 
 #ifdef CONFIG_X86_64

arch/x86/kvm/mmu/mmu.c

···
 out_unlock:
 	write_unlock(&vcpu->kvm->mmu_lock);
 
-	return 0;
+	return r;
 }
 
 static int mmu_alloc_special_roots(struct kvm_vcpu *vcpu)

arch/x86/kvm/x86.c

···
 		likely(!pic_in_kernel(vcpu->kvm));
 }
 
+/* Called within kvm->srcu read side.  */
 static void post_kvm_run_save(struct kvm_vcpu *vcpu)
 {
 	struct kvm_run *kvm_run = vcpu->run;
···
 	kvm_run->cr8 = kvm_get_cr8(vcpu);
 	kvm_run->apic_base = kvm_get_apic_base(vcpu);
 
-	/*
-	 * The call to kvm_ready_for_interrupt_injection() may end up in
-	 * kvm_xen_has_interrupt() which may require the srcu lock to be
-	 * held, to protect against changes in the vcpu_info address.
-	 */
-	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 	kvm_run->ready_for_interrupt_injection =
 		pic_in_kernel(vcpu->kvm) ||
 		kvm_vcpu_ready_for_interrupt_injection(vcpu);
-	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
 
 	if (is_smm(vcpu))
 		kvm_run->flags |= KVM_RUN_X86_SMM;
···
 EXPORT_SYMBOL_GPL(__kvm_request_immediate_exit);
 
 /*
+ * Called within kvm->srcu read side.
  * Returns 1 to let vcpu_run() continue the guest execution loop without
  * exiting to the userspace.  Otherwise, the value will be returned to the
  * userspace.
···
 	return r;
 }
 
+/* Called within kvm->srcu read side.  */
 static inline int vcpu_block(struct kvm *kvm, struct kvm_vcpu *vcpu)
 {
 	bool hv_timer;
···
 		!vcpu->arch.apf.halted);
 }
 
+/* Called within kvm->srcu read side.  */
 static int vcpu_run(struct kvm_vcpu *vcpu)
 {
 	int r;
 	struct kvm *kvm = vcpu->kvm;
 
-	vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
 	vcpu->arch.l1tf_flush_l1d = true;
 
 	for (;;) {
···
 		if (__xfer_to_guest_mode_work_pending()) {
 			srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
 			r = xfer_to_guest_mode_handle_work(vcpu);
+			vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
 			if (r)
 				return r;
-			vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
 		}
 	}
-
-	srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
 
 	return r;
 }
···
 int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 {
 	struct kvm_run *kvm_run = vcpu->run;
+	struct kvm *kvm = vcpu->kvm;
 	int r;
 
 	vcpu_load(vcpu);
···
 	kvm_run->flags = 0;
 	kvm_load_guest_fpu(vcpu);
 
+	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 	if (unlikely(vcpu->arch.mp_state == KVM_MP_STATE_UNINITIALIZED)) {
 		if (kvm_run->immediate_exit) {
 			r = -EINTR;
···
 		 * use before KVM has ever run the vCPU.
 		 */
 		WARN_ON_ONCE(kvm_lapic_hv_timer_in_use(vcpu));
+
+		srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
 		kvm_vcpu_block(vcpu);
+		vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
+
 		if (kvm_apic_accept_events(vcpu) < 0) {
 			r = 0;
 			goto out;
···
 	if (kvm_run->kvm_valid_regs)
 		store_regs(vcpu);
 	post_kvm_run_save(vcpu);
-	kvm_sigset_deactivate(vcpu);
+	srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
 
+	kvm_sigset_deactivate(vcpu);
 	vcpu_put(vcpu);
 	return r;
 }