Merge branch 'kvm-updates/2.6.39' of git://git.kernel.org/pub/scm/virt/kvm/kvm

* 'kvm-updates/2.6.39' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: move and fix substitue search for missing CPUID entries
KVM: fix XSAVE bit scanning
KVM: Enable async page fault processing
KVM: fix crash on irqfd deassign

arch/x86/kvm/x86.c

···
 		int i;
 
 		entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
-		for (i = 1; *nent < maxnent; ++i) {
-			if (entry[i - 1].eax == 0 && i != 2)
-				break;
+		for (i = 1; *nent < maxnent && i < 64; ++i) {
+			if (entry[i].eax == 0)
+				continue;
 			do_cpuid_1_ent(&entry[i], function, i);
 			entry[i].flags |=
 			       KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
···
 			best = e;
 			break;
 		}
-		/*
-		 * Both basic or both extended?
-		 */
-		if (((e->function ^ function) & 0x80000000) == 0)
-			if (!best || e->function > best->function)
-				best = e;
 	}
 	return best;
 }
···
 	return 36;
 }
 
+/*
+ * If no match is found, check whether we exceed the vCPU's limit
+ * and return the content of the highest valid _standard_ leaf instead.
+ * This is to satisfy the CPUID specification.
+ */
+static struct kvm_cpuid_entry2* check_cpuid_limit(struct kvm_vcpu *vcpu,
+                                                  u32 function, u32 index)
+{
+	struct kvm_cpuid_entry2 *maxlevel;
+
+	maxlevel = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0);
+	if (!maxlevel || maxlevel->eax >= function)
+		return NULL;
+	if (function & 0x80000000) {
+		maxlevel = kvm_find_cpuid_entry(vcpu, 0, 0);
+		if (!maxlevel)
+			return NULL;
+	}
+	return kvm_find_cpuid_entry(vcpu, maxlevel->eax, index);
+}
+
 void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
 {
 	u32 function, index;
···
 	kvm_register_write(vcpu, VCPU_REGS_RCX, 0);
 	kvm_register_write(vcpu, VCPU_REGS_RDX, 0);
 	best = kvm_find_cpuid_entry(vcpu, function, index);
+
+	if (!best)
+		best = check_cpuid_limit(vcpu, function, index);
+
 	if (best) {
 		kvm_register_write(vcpu, VCPU_REGS_RAX, best->eax);
 		kvm_register_write(vcpu, VCPU_REGS_RBX, best->ebx);

virt/kvm/eventfd.c

···
 	 * We know no new events will be scheduled at this point, so block
 	 * until all previously outstanding events have completed
 	 */
-	flush_work(&irqfd->inject);
+	flush_work_sync(&irqfd->inject);
 
 	/*
 	 * It is now safe to release the object's resources

virt/kvm/kvm_main.c

···
 	return fault_pfn;
 }
 
+int get_user_page_nowait(struct task_struct *tsk, struct mm_struct *mm,
+	unsigned long start, int write, struct page **page)
+{
+	int flags = FOLL_TOUCH | FOLL_NOWAIT | FOLL_HWPOISON | FOLL_GET;
+
+	if (write)
+		flags |= FOLL_WRITE;
+
+	return __get_user_pages(tsk, mm, start, 1, flags, page, NULL, NULL);
+}
+
 static inline int check_user_page_hwpoison(unsigned long addr)
 {
 	int rc, flags = FOLL_TOUCH | FOLL_HWPOISON | FOLL_WRITE;
···
 		if (writable)
 			*writable = write_fault;
 
-		npages = get_user_pages_fast(addr, 1, write_fault, page);
+		if (async) {
+			down_read(&current->mm->mmap_sem);
+			npages = get_user_page_nowait(current, current->mm,
+						     addr, write_fault, page);
+			up_read(&current->mm->mmap_sem);
+		} else
+			npages = get_user_pages_fast(addr, 1, write_fault,
+						     page);
 
 		/* map read fault as writable if possible */
 		if (unlikely(!write_fault) && npages == 1) {
···
 			return get_fault_pfn();
 
 		down_read(&current->mm->mmap_sem);
-		if (check_user_page_hwpoison(addr)) {
+		if (npages == -EHWPOISON ||
+			(!async && check_user_page_hwpoison(addr))) {
 			up_read(&current->mm->mmap_sem);
 			get_page(hwpoison_page);
 			return page_to_pfn(hwpoison_page);