1 files changed, 104 insertions, 66 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 47e021bdcc94..eca63625aee4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -271,8 +271,7 @@ static struct kmem_cache *x86_emulator_cache;
  * When called, it means the previous get/set msr reached an invalid msr.
  * Return true if we want to ignore/silent this failed msr access.
  */
-static bool kvm_msr_ignored_check(struct kvm_vcpu *vcpu, u32 msr,
-				  u64 data, bool write)
+static bool kvm_msr_ignored_check(u32 msr, u64 data, bool write)
 {
 	const char *op = write ? "wrmsr" : "rdmsr";
 
@@ -1445,7 +1444,7 @@ static int do_get_msr_feature(struct kvm_vcpu *vcpu, unsigned index, u64 *data)
 	if (r == KVM_MSR_RET_INVALID) {
 		/* Unconditionally clear the output for simplicity */
 		*data = 0;
-		if (kvm_msr_ignored_check(vcpu, index, 0, false))
+		if (kvm_msr_ignored_check(index, 0, false))
 			r = 0;
 	}
 
@@ -1526,35 +1525,44 @@ EXPORT_SYMBOL_GPL(kvm_enable_efer_bits);
 
 bool kvm_msr_allowed(struct kvm_vcpu *vcpu, u32 index, u32 type)
 {
+	struct kvm_x86_msr_filter *msr_filter;
+	struct msr_bitmap_range *ranges;
 	struct kvm *kvm = vcpu->kvm;
-	struct msr_bitmap_range *ranges = kvm->arch.msr_filter.ranges;
-	u32 count = kvm->arch.msr_filter.count;
-	u32 i;
-	bool r = kvm->arch.msr_filter.default_allow;
+	bool allowed;
 	int idx;
+	u32 i;
 
-	/* MSR filtering not set up or x2APIC enabled, allow everything */
-	if (!count || (index >= 0x800 && index <= 0x8ff))
+	/* x2APIC MSRs do not support filtering. */
+	if (index >= 0x800 && index <= 0x8ff)
 		return true;
 
-	/* Prevent collision with set_msr_filter */
 	idx = srcu_read_lock(&kvm->srcu);
 
-	for (i = 0; i < count; i++) {
+	msr_filter = srcu_dereference(kvm->arch.msr_filter, &kvm->srcu);
+	if (!msr_filter) {
+		allowed = true;
+		goto out;
+	}
+
+	allowed = msr_filter->default_allow;
+	ranges = msr_filter->ranges;
+
+	for (i = 0; i < msr_filter->count; i++) {
 		u32 start = ranges[i].base;
 		u32 end = start + ranges[i].nmsrs;
 		u32 flags = ranges[i].flags;
 		unsigned long *bitmap = ranges[i].bitmap;
 
 		if ((index >= start) && (index < end) && (flags & type)) {
-			r = !!test_bit(index - start, bitmap);
+			allowed = !!test_bit(index - start, bitmap);
 			break;
 		}
 	}
 
+out:
 	srcu_read_unlock(&kvm->srcu, idx);
 
-	return r;
+	return allowed;
 }
 EXPORT_SYMBOL_GPL(kvm_msr_allowed);
 
@@ -1611,7 +1619,7 @@ static int kvm_set_msr_ignored_check(struct kvm_vcpu *vcpu,
 	int ret = __kvm_set_msr(vcpu, index, data, host_initiated);
 
 	if (ret == KVM_MSR_RET_INVALID)
-		if (kvm_msr_ignored_check(vcpu, index, data, true))
+		if (kvm_msr_ignored_check(index, data, true))
 			ret = 0;
 
 	return ret;
@@ -1649,7 +1657,7 @@ static int kvm_get_msr_ignored_check(struct kvm_vcpu *vcpu,
 	if (ret == KVM_MSR_RET_INVALID) {
 		/* Unconditionally clear *data for simplicity */
 		*data = 0;
-		if (kvm_msr_ignored_check(vcpu, index, 0, false))
+		if (kvm_msr_ignored_check(index, 0, false))
 			ret = 0;
 	}
 
@@ -2320,7 +2328,7 @@ static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 data)
 	kvm_vcpu_write_tsc_offset(vcpu, offset);
 	raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
 
-	spin_lock(&kvm->arch.pvclock_gtod_sync_lock);
+	spin_lock_irqsave(&kvm->arch.pvclock_gtod_sync_lock, flags);
 	if (!matched) {
 		kvm->arch.nr_vcpus_matched_tsc = 0;
 	} else if (!already_matched) {
@@ -2328,7 +2336,7 @@ static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 data)
 	}
 
 	kvm_track_tsc_matching(vcpu);
-	spin_unlock(&kvm->arch.pvclock_gtod_sync_lock);
+	spin_unlock_irqrestore(&kvm->arch.pvclock_gtod_sync_lock, flags);
 }
 
 static inline void adjust_tsc_offset_guest(struct kvm_vcpu *vcpu,
@@ -2550,11 +2558,16 @@ static void kvm_gen_update_masterclock(struct kvm *kvm)
 	int i;
 	struct kvm_vcpu *vcpu;
 	struct kvm_arch *ka = &kvm->arch;
+	unsigned long flags;
+
+	kvm_hv_invalidate_tsc_page(kvm);
 
-	spin_lock(&ka->pvclock_gtod_sync_lock);
 	kvm_make_mclock_inprogress_request(kvm);
+
 	/* no guest entries from this point */
+	spin_lock_irqsave(&ka->pvclock_gtod_sync_lock, flags);
 	pvclock_update_vm_gtod_copy(kvm);
+	spin_unlock_irqrestore(&ka->pvclock_gtod_sync_lock, flags);
 
 	kvm_for_each_vcpu(i, vcpu, kvm)
 		kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
@@ -2562,8 +2575,6 @@ static void kvm_gen_update_masterclock(struct kvm *kvm)
 	/* guest entries allowed */
 	kvm_for_each_vcpu(i, vcpu, kvm)
 		kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu);
-
-	spin_unlock(&ka->pvclock_gtod_sync_lock);
 #endif
 }
 
@@ -2571,17 +2582,18 @@ u64 get_kvmclock_ns(struct kvm *kvm)
 {
 	struct kvm_arch *ka = &kvm->arch;
 	struct pvclock_vcpu_time_info hv_clock;
+	unsigned long flags;
 	u64 ret;
 
-	spin_lock(&ka->pvclock_gtod_sync_lock);
+	spin_lock_irqsave(&ka->pvclock_gtod_sync_lock, flags);
 	if (!ka->use_master_clock) {
-		spin_unlock(&ka->pvclock_gtod_sync_lock);
+		spin_unlock_irqrestore(&ka->pvclock_gtod_sync_lock, flags);
 		return get_kvmclock_base_ns() + ka->kvmclock_offset;
 	}
 
 	hv_clock.tsc_timestamp = ka->master_cycle_now;
 	hv_clock.system_time = ka->master_kernel_ns + ka->kvmclock_offset;
-	spin_unlock(&ka->pvclock_gtod_sync_lock);
+	spin_unlock_irqrestore(&ka->pvclock_gtod_sync_lock, flags);
 
 	/* both __this_cpu_read() and rdtsc() should be on the same cpu */
 	get_cpu();
@@ -2675,13 +2687,13 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
 	 * If the host uses TSC clock, then passthrough TSC as stable
 	 * to the guest.
 	 */
-	spin_lock(&ka->pvclock_gtod_sync_lock);
+	spin_lock_irqsave(&ka->pvclock_gtod_sync_lock, flags);
 	use_master_clock = ka->use_master_clock;
 	if (use_master_clock) {
 		host_tsc = ka->master_cycle_now;
 		kernel_ns = ka->master_kernel_ns;
 	}
-	spin_unlock(&ka->pvclock_gtod_sync_lock);
+	spin_unlock_irqrestore(&ka->pvclock_gtod_sync_lock, flags);
 
 	/* Keep irq disabled to prevent changes to the clock */
 	local_irq_save(flags);
@@ -5352,25 +5364,34 @@ split_irqchip_unlock:
 	return r;
 }
 
-static void kvm_clear_msr_filter(struct kvm *kvm)
+static struct kvm_x86_msr_filter *kvm_alloc_msr_filter(bool default_allow)
+{
+	struct kvm_x86_msr_filter *msr_filter;
+
+	msr_filter = kzalloc(sizeof(*msr_filter), GFP_KERNEL_ACCOUNT);
+	if (!msr_filter)
+		return NULL;
+
+	msr_filter->default_allow = default_allow;
+	return msr_filter;
+}
+
+static void kvm_free_msr_filter(struct kvm_x86_msr_filter *msr_filter)
 {
 	u32 i;
-	u32 count = kvm->arch.msr_filter.count;
-	struct msr_bitmap_range ranges[16];
 
-	mutex_lock(&kvm->lock);
-	kvm->arch.msr_filter.count = 0;
-	memcpy(ranges, kvm->arch.msr_filter.ranges, count * sizeof(ranges[0]));
-	mutex_unlock(&kvm->lock);
-	synchronize_srcu(&kvm->srcu);
+	if (!msr_filter)
+		return;
 
-	for (i = 0; i < count; i++)
-		kfree(ranges[i].bitmap);
+	for (i = 0; i < msr_filter->count; i++)
+		kfree(msr_filter->ranges[i].bitmap);
+
+	kfree(msr_filter);
 }
 
-static int kvm_add_msr_filter(struct kvm *kvm, struct kvm_msr_filter_range *user_range)
+static int kvm_add_msr_filter(struct kvm_x86_msr_filter *msr_filter,
+			      struct kvm_msr_filter_range *user_range)
 {
-	struct msr_bitmap_range *ranges = kvm->arch.msr_filter.ranges;
 	struct msr_bitmap_range range;
 	unsigned long *bitmap = NULL;
 	size_t bitmap_size;
@@ -5404,11 +5425,9 @@ static int kvm_add_msr_filter(struct kvm *kvm, struct kvm_msr_filter_range *user
 		goto err;
 	}
 
-	/* Everything ok, add this range identifier to our global pool */
-	ranges[kvm->arch.msr_filter.count] = range;
-	/* Make sure we filled the array before we tell anyone to walk it */
-	smp_wmb();
-	kvm->arch.msr_filter.count++;
+	/* Everything ok, add this range identifier. */
+	msr_filter->ranges[msr_filter->count] = range;
+	msr_filter->count++;
 
 	return 0;
 err:
@@ -5419,10 +5438,11 @@ err:
 static int kvm_vm_ioctl_set_msr_filter(struct kvm *kvm, void __user *argp)
 {
 	struct kvm_msr_filter __user *user_msr_filter = argp;
+	struct kvm_x86_msr_filter *new_filter, *old_filter;
 	struct kvm_msr_filter filter;
 	bool default_allow;
-	int r = 0;
 	bool empty = true;
+	int r = 0;
 	u32 i;
 
 	if (copy_from_user(&filter, user_msr_filter, sizeof(filter)))
@@ -5435,25 +5455,32 @@ static int kvm_vm_ioctl_set_msr_filter(struct kvm *kvm, void __user *argp)
 	if (empty && !default_allow)
 		return -EINVAL;
 
-	kvm_clear_msr_filter(kvm);
-
-	kvm->arch.msr_filter.default_allow = default_allow;
+	new_filter = kvm_alloc_msr_filter(default_allow);
+	if (!new_filter)
+		return -ENOMEM;
 
-	/*
-	 * Protect from concurrent calls to this function that could trigger
-	 * a TOCTOU violation on kvm->arch.msr_filter.count.
-	 */
-	mutex_lock(&kvm->lock);
 	for (i = 0; i < ARRAY_SIZE(filter.ranges); i++) {
-		r = kvm_add_msr_filter(kvm, &filter.ranges[i]);
-		if (r)
-			break;
+		r = kvm_add_msr_filter(new_filter, &filter.ranges[i]);
+		if (r) {
+			kvm_free_msr_filter(new_filter);
+			return r;
+		}
 	}
 
+	mutex_lock(&kvm->lock);
+
+	/* The per-VM filter is protected by kvm->lock... */
+	old_filter = srcu_dereference_check(kvm->arch.msr_filter, &kvm->srcu, 1);
+
+	rcu_assign_pointer(kvm->arch.msr_filter, new_filter);
+	synchronize_srcu(&kvm->srcu);
+
+	kvm_free_msr_filter(old_filter);
+
 	kvm_make_all_cpus_request(kvm, KVM_REQ_MSR_FILTER_CHANGED);
 	mutex_unlock(&kvm->lock);
 
-	return r;
+	return 0;
 }
 
 long kvm_arch_vm_ioctl(struct file *filp,
@@ -5700,6 +5727,7 @@ set_pit2_out:
 	}
 #endif
 	case KVM_SET_CLOCK: {
+		struct kvm_arch *ka = &kvm->arch;
 		struct kvm_clock_data user_ns;
 		u64 now_ns;
 
@@ -5718,8 +5746,22 @@ set_pit2_out:
 		 * pvclock_update_vm_gtod_copy().
 		 */
 		kvm_gen_update_masterclock(kvm);
-		now_ns = get_kvmclock_ns(kvm);
-		kvm->arch.kvmclock_offset += user_ns.clock - now_ns;
+
+		/*
+		 * This pairs with kvm_guest_time_update(): when masterclock is
+		 * in use, we use master_kernel_ns + kvmclock_offset to set
+		 * unsigned 'system_time' so if we use get_kvmclock_ns() (which
+		 * is slightly ahead) here we risk going negative on unsigned
+		 * 'system_time' when 'user_ns.clock' is very small.
+		 */
+		spin_lock_irq(&ka->pvclock_gtod_sync_lock);
+		if (kvm->arch.use_master_clock)
+			now_ns = ka->master_kernel_ns;
+		else
+			now_ns = get_kvmclock_base_ns();
+		ka->kvmclock_offset = user_ns.clock - now_ns;
+		spin_unlock_irq(&ka->pvclock_gtod_sync_lock);
+
 		kvm_make_all_cpus_request(kvm, KVM_REQ_CLOCK_UPDATE);
 		break;
 	}
@@ -6603,7 +6645,7 @@ static int kvm_emulate_wbinvd_noskip(struct kvm_vcpu *vcpu)
 		int cpu = get_cpu();
 
 		cpumask_set_cpu(cpu, vcpu->arch.wbinvd_dirty_mask);
-		smp_call_function_many(vcpu->arch.wbinvd_dirty_mask,
+		on_each_cpu_mask(vcpu->arch.wbinvd_dirty_mask,
 				wbinvd_ipi, NULL, 1);
 		put_cpu();
 		cpumask_clear(vcpu->arch.wbinvd_dirty_mask);
@@ -7698,6 +7740,7 @@ static void kvm_hyperv_tsc_notifier(void)
 	struct kvm *kvm;
 	struct kvm_vcpu *vcpu;
 	int cpu;
+	unsigned long flags;
 
 	mutex_lock(&kvm_lock);
 	list_for_each_entry(kvm, &vm_list, vm_list)
@@ -7713,17 +7756,15 @@ static void kvm_hyperv_tsc_notifier(void)
 	list_for_each_entry(kvm, &vm_list, vm_list) {
 		struct kvm_arch *ka = &kvm->arch;
 
-		spin_lock(&ka->pvclock_gtod_sync_lock);
-
+		spin_lock_irqsave(&ka->pvclock_gtod_sync_lock, flags);
 		pvclock_update_vm_gtod_copy(kvm);
+		spin_unlock_irqrestore(&ka->pvclock_gtod_sync_lock, flags);
 
 		kvm_for_each_vcpu(cpu, vcpu, kvm)
 			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
 
 		kvm_for_each_vcpu(cpu, vcpu, kvm)
 			kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu);
-
-		spin_unlock(&ka->pvclock_gtod_sync_lock);
 	}
 	mutex_unlock(&kvm_lock);
 }
@@ -10634,8 +10675,6 @@ void kvm_arch_pre_destroy_vm(struct kvm *kvm)
 
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
-	u32 i;
-
 	if (current->mm == kvm->mm) {
 		/*
 		 * Free memory regions allocated on behalf of userspace,
@@ -10651,8 +10690,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 		mutex_unlock(&kvm->slots_lock);
 	}
 	static_call_cond(kvm_x86_vm_destroy)(kvm);
-	for (i = 0; i < kvm->arch.msr_filter.count; i++)
-		kfree(kvm->arch.msr_filter.ranges[i].bitmap);
+	kvm_free_msr_filter(srcu_dereference_check(kvm->arch.msr_filter, &kvm->srcu, 1));
 	kvm_pic_destroy(kvm);
 	kvm_ioapic_destroy(kvm);
 	kvm_free_vcpus(kvm);