* Fixes for CONFIG_KVM_COMPAT=n

* Two updates to the IFU erratum
 * selftests build fix
 * Brown paper bag fix
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull more KVM fixes from Paolo Bonzini:

 - fixes for CONFIG_KVM_COMPAT=n

 - two updates to the IFU erratum

 - selftests build fix

 - brown paper bag fix

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: Add a comment describing the /dev/kvm no_compat handling
  KVM: x86/mmu: Take slots_lock when using kvm_mmu_zap_all_fast()
  KVM: Forbid /dev/kvm being opened by a compat task when CONFIG_KVM_COMPAT=n
  KVM: X86: Reset the three MSR list number variables to 0 in kvm_init_msr_list()
  selftests: kvm: fix build with glibc >= 2.30
  kvm: x86: disable shattered huge page recovery for PREEMPT_RT.

arch/x86/kvm/mmu.c

@@ -51,7 +51,12 @@
 extern bool itlb_multihit_kvm_mitigation;
 
 static int __read_mostly nx_huge_pages = -1;
+#ifdef CONFIG_PREEMPT_RT
+/* Recovery can cause latency spikes, disable it for PREEMPT_RT.  */
+static uint __read_mostly nx_huge_pages_recovery_ratio = 0;
+#else
 static uint __read_mostly nx_huge_pages_recovery_ratio = 60;
+#endif
 
 static int set_nx_huge_pages(const char *val, const struct kernel_param *kp);
 static int set_nx_huge_pages_recovery_ratio(const char *val, const struct kernel_param *kp);
@@ -6280,14 +6285,13 @@ static int set_nx_huge_pages(const char *val, const struct kernel_param *kp)
 
 	if (new_val != old_val) {
 		struct kvm *kvm;
-		int idx;
 
 		mutex_lock(&kvm_lock);
 
 		list_for_each_entry(kvm, &vm_list, vm_list) {
-			idx = srcu_read_lock(&kvm->srcu);
+			mutex_lock(&kvm->slots_lock);
 			kvm_mmu_zap_all_fast(kvm);
-			srcu_read_unlock(&kvm->srcu, idx);
+			mutex_unlock(&kvm->slots_lock);
 
 			wake_up_process(kvm->arch.nx_lpage_recovery_thread);
 		}

arch/x86/kvm/x86.c

@@ -5130,6 +5130,10 @@ static void kvm_init_msr_list(void)
 
 	perf_get_x86_pmu_capability(&x86_pmu);
 
+	num_msrs_to_save = 0;
+	num_emulated_msrs = 0;
+	num_msr_based_features = 0;
+
 	for (i = 0; i < ARRAY_SIZE(msrs_to_save_all); i++) {
 		if (rdmsr_safe(msrs_to_save_all[i], &dummy[0], &dummy[1]) < 0)
 			continue;

tools/testing/selftests/kvm/lib/assert.c

@@ -55,7 +55,7 @@ static void test_dump_stack(void)
 #pragma GCC diagnostic pop
 }
 
-static pid_t gettid(void)
+static pid_t _gettid(void)
 {
 	return syscall(SYS_gettid);
 }
@@ -72,7 +72,7 @@ test_assert(bool exp, const char *exp_str,
 		fprintf(stderr, "==== Test Assertion Failure ====\n"
 			"  %s:%u: %s\n"
 			"  pid=%d tid=%d - %s\n",
-			file, line, exp_str, getpid(), gettid(),
+			file, line, exp_str, getpid(), _gettid(),
 			strerror(errno));
 		test_dump_stack();
 		if (fmt) {

virt/kvm/kvm_main.c

@@ -122,9 +122,22 @@ static long kvm_vcpu_compat_ioctl(struct file *file, unsigned int ioctl,
 				  unsigned long arg);
 #define KVM_COMPAT(c)	.compat_ioctl	= (c)
 #else
+/*
+ * For architectures that don't implement a compat infrastructure,
+ * adopt a double line of defense:
+ * - Prevent a compat task from opening /dev/kvm
+ * - If the open has been done by a 64bit task, and the KVM fd
+ *   passed to a compat task, let the ioctls fail.
+ */
 static long kvm_no_compat_ioctl(struct file *file, unsigned int ioctl,
 				unsigned long arg) { return -EINVAL; }
-#define KVM_COMPAT(c)	.compat_ioctl	= kvm_no_compat_ioctl
+
+static int kvm_no_compat_open(struct inode *inode, struct file *file)
+{
+	return is_compat_task() ? -ENODEV : 0;
+}
+#define KVM_COMPAT(c)	.compat_ioctl	= kvm_no_compat_ioctl,	\
+			.open		= kvm_no_compat_open
 #endif
 static int hardware_enable_all(void);
 static void hardware_disable_all(void);