[PATCH 0/4] KVM: arm/arm64: Fix locking issues

[PATCH 0/4] KVM: arm/arm64: Fix locking issues

[Andre Przywara]

Jan recently reported lockdep complaints regarding various locks in our
VGIC emulation [1][2].
This boiled down to two separate issues:
- When promoting the vgic_irq->irq_lock to require IRQs being disabled,
  we forgot to amend some instances of this lock on the way. Also this
  needs to be applied to dependent locks as well. The first two patches
  fix that. The patch split is designed to simplify backporting.
  Those patches have been posted before, I am resending them as part
  of this series.
- Calling kvm_read_guest() requires us to be inside an SRCU critical
  section. On some architectures we are always in it when handling VCPU
  exits, but on ARM we need to lock it individually. Patches 3 and 4
  fix that, the split is again made to ease backporting.
  Each of the hunks fix an indiviual commit, but I refrained from
  splitting this down into eight patches just to put proper Fixes: tags
  on it. Eventually those commits are part of one out of two series, I put
  the respective kernel release version as a tag to the Cc: stable line.

I couldn't reproduce the full lockdep splat on my setup, but at least
could show one instance and prove that these patches fixes that.

Thanks to Jan for reporting.

Cheers,
Andre.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/575718.html
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/575833.html

Andre Przywara (4):
  KVM: ARM: Properly protect VGIC locks from IRQs
  KVM: ARM: VGIC/ITS: Promote irq_lock() in update_affinity
  KVM: arm/arm64: VGIC/ITS: protect kvm_read_guest() calls with SRCU lock
  KVM: arm/arm64: VGIC/ITS save/restore: protect kvm_read_guest() calls

 arch/arm/include/asm/kvm_mmu.h   | 16 ++++++++++++++++
 arch/arm64/include/asm/kvm_mmu.h | 16 ++++++++++++++++
 virt/kvm/arm/vgic/vgic-debug.c   |  5 +++--
 virt/kvm/arm/vgic/vgic-its.c     | 34 +++++++++++++++++++---------------
 virt/kvm/arm/vgic/vgic-v3.c      |  4 ++--
 virt/kvm/arm/vgic/vgic.c         | 22 ++++++++++++++--------
 6 files changed, 70 insertions(+), 27 deletions(-)

-- 
2.14.1

[PATCH 1/4] KVM: arm/arm64: Properly protect VGIC locks from IRQs

[Andre Przywara]

As Jan reported [1], lockdep complains about the VGIC not being bullet
proof. This seems to be due to two issues:
- When commit 006df0f34930 ("KVM: arm/arm64: Support calling
  vgic_update_irq_pending from irq context") promoted irq_lock and
  ap_list_lock to _irqsave, we forgot two instances of irq_lock.
  lockdeps seems to pick those up.
- If a lock is _irqsave, any other locks we take inside them should be
  _irqsafe as well. So the lpi_list_lock needs to be promoted also.

This fixes both issues by simply making the remaining instances of those
locks _irqsave.
One irq_lock is addressed in a separate patch, to simplify backporting.

Cc: stable at vger.kernel.org
Fixes: 006df0f34930 ("KVM: arm/arm64: Support calling vgic_update_irq_pending from irq context")
Reported-by: Jan Glauber <jan.glauber@caviumnetworks.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/575718.html
---
 virt/kvm/arm/vgic/vgic-debug.c |  5 +++--
 virt/kvm/arm/vgic/vgic-its.c   | 10 ++++++----
 virt/kvm/arm/vgic/vgic.c       | 22 ++++++++++++++--------
 3 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-debug.c b/virt/kvm/arm/vgic/vgic-debug.c
index 10b38178cff2..4ffc0b5e6105 100644
--- a/virt/kvm/arm/vgic/vgic-debug.c
+++ b/virt/kvm/arm/vgic/vgic-debug.c
@@ -211,6 +211,7 @@ static int vgic_debug_show(struct seq_file *s, void *v)
 	struct vgic_state_iter *iter = (struct vgic_state_iter *)v;
 	struct vgic_irq *irq;
 	struct kvm_vcpu *vcpu = NULL;
+	unsigned long flags;
 
 	if (iter->dist_id == 0) {
 		print_dist_state(s, &kvm->arch.vgic);
@@ -227,9 +228,9 @@ static int vgic_debug_show(struct seq_file *s, void *v)
 		irq = &kvm->arch.vgic.spis[iter->intid - VGIC_NR_PRIVATE_IRQS];
 	}
 
-	spin_lock(&irq->irq_lock);
+	spin_lock_irqsave(&irq->irq_lock, flags);
 	print_irq_state(s, irq, vcpu);
-	spin_unlock(&irq->irq_lock);
+	spin_unlock_irqrestore(&irq->irq_lock, flags);
 
 	return 0;
 }
diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index a8f07243aa9f..41abf92f2699 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -52,6 +52,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
 	struct vgic_irq *irq = vgic_get_irq(kvm, NULL, intid), *oldirq;
+	unsigned long flags;
 	int ret;
 
 	/* In this case there is no put, since we keep the reference. */
@@ -71,7 +72,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
 	irq->intid = intid;
 	irq->target_vcpu = vcpu;
 
-	spin_lock(&dist->lpi_list_lock);
+	spin_lock_irqsave(&dist->lpi_list_lock, flags);
 
 	/*
 	 * There could be a race with another vgic_add_lpi(), so we need to
@@ -99,7 +100,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
 	dist->lpi_list_count++;
 
 out_unlock:
-	spin_unlock(&dist->lpi_list_lock);
+	spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
 
 	/*
 	 * We "cache" the configuration table entries in our struct vgic_irq's.
@@ -315,6 +316,7 @@ static int vgic_copy_lpi_list(struct kvm_vcpu *vcpu, u32 **intid_ptr)
 {
 	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
 	struct vgic_irq *irq;
+	unsigned long flags;
 	u32 *intids;
 	int irq_count, i = 0;
 
@@ -330,7 +332,7 @@ static int vgic_copy_lpi_list(struct kvm_vcpu *vcpu, u32 **intid_ptr)
 	if (!intids)
 		return -ENOMEM;
 
-	spin_lock(&dist->lpi_list_lock);
+	spin_lock_irqsave(&dist->lpi_list_lock, flags);
 	list_for_each_entry(irq, &dist->lpi_list_head, lpi_list) {
 		if (i == irq_count)
 			break;
@@ -339,7 +341,7 @@ static int vgic_copy_lpi_list(struct kvm_vcpu *vcpu, u32 **intid_ptr)
 			continue;
 		intids[i++] = irq->intid;
 	}
-	spin_unlock(&dist->lpi_list_lock);
+	spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
 
 	*intid_ptr = intids;
 	return i;
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 27219313a406..1dfb5b2f1b12 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -43,9 +43,13 @@ struct vgic_global kvm_vgic_global_state __ro_after_init = {
  * kvm->lock (mutex)
  *   its->cmd_lock (mutex)
  *     its->its_lock (mutex)
- *       vgic_cpu->ap_list_lock
- *         kvm->lpi_list_lock
- *           vgic_irq->irq_lock
+ *       vgic_cpu->ap_list_lock		must be taken with IRQs disabled
+ *         kvm->lpi_list_lock		must be taken with IRQs disabled
+ *           vgic_irq->irq_lock		must be taken with IRQs disabled
+ *
+ * As the ap_list_lock might be taken from the timer interrupt handler,
+ * we have to disable IRQs before taking this lock and everything lower
+ * than it.
  *
  * If you need to take multiple locks, always take the upper lock first,
  * then the lower ones, e.g. first take the its_lock, then the irq_lock.
@@ -72,8 +76,9 @@ static struct vgic_irq *vgic_get_lpi(struct kvm *kvm, u32 intid)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
 	struct vgic_irq *irq = NULL;
+	unsigned long flags;
 
-	spin_lock(&dist->lpi_list_lock);
+	spin_lock_irqsave(&dist->lpi_list_lock, flags);
 
 	list_for_each_entry(irq, &dist->lpi_list_head, lpi_list) {
 		if (irq->intid != intid)
@@ -89,7 +94,7 @@ static struct vgic_irq *vgic_get_lpi(struct kvm *kvm, u32 intid)
 	irq = NULL;
 
 out_unlock:
-	spin_unlock(&dist->lpi_list_lock);
+	spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
 
 	return irq;
 }
@@ -134,19 +139,20 @@ static void vgic_irq_release(struct kref *ref)
 void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
+	unsigned long flags;
 
 	if (irq->intid < VGIC_MIN_LPI)
 		return;
 
-	spin_lock(&dist->lpi_list_lock);
+	spin_lock_irqsave(&dist->lpi_list_lock, flags);
 	if (!kref_put(&irq->refcount, vgic_irq_release)) {
-		spin_unlock(&dist->lpi_list_lock);
+		spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
 		return;
 	};
 
 	list_del(&irq->lpi_list);
 	dist->lpi_list_count--;
-	spin_unlock(&dist->lpi_list_lock);
+	spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
 
 	kfree(irq);
 }
-- 
2.14.1

[PATCH 2/4] KVM: arm/arm64: VGIC/ITS: Promote irq_lock() in update_affinity

[Andre Przywara]

Apparently the development of update_affinity() overlapped with the
promotion of irq_lock to be _irqsave, so the patch didn't convert this
lock over. This will make lockdep complain.

Fix this by disabling IRQs around the lock.

Cc: stable at vger.kernel.org
Fixes: 08c9fd042117 ("KVM: arm/arm64: vITS: Add a helper to update the affinity of an LPI")
Reported-by: Jan Glauber <jan.glauber@caviumnetworks.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 virt/kvm/arm/vgic/vgic-its.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 41abf92f2699..51a80b600632 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -350,10 +350,11 @@ static int vgic_copy_lpi_list(struct kvm_vcpu *vcpu, u32 **intid_ptr)
 static int update_affinity(struct vgic_irq *irq, struct kvm_vcpu *vcpu)
 {
 	int ret = 0;
+	unsigned long flags;
 
-	spin_lock(&irq->irq_lock);
+	spin_lock_irqsave(&irq->irq_lock, flags);
 	irq->target_vcpu = vcpu;
-	spin_unlock(&irq->irq_lock);
+	spin_unlock_irqrestore(&irq->irq_lock, flags);
 
 	if (irq->hw) {
 		struct its_vlpi_map map;
-- 
2.14.1

[PATCH 3/4] KVM: arm/arm64: VGIC/ITS: protect kvm_read_guest() calls with SRCU lock

[Andre Przywara]

kvm_read_guest() will eventually look up in kvm_memslots(), which requires
either to hold the kvm->slots_lock or to be inside a kvm->srcu critical
section.
In contrast to x86 and s390 we don't take the SRCU lock on every guest
exit, so we have to do it individually for each kvm_read_guest() call.

Provide a wrapper which does that and use that everywhere.

Note that ending the SRCU critical section before returning from the
kvm_read_guest() wrapper is safe, because the data has been *copied*, so
we don't need to rely on valid references to the memslot anymore.

Cc: Stable <stable@vger.kernel.org> # 4.8+
Reported-by: Jan Glauber <jan.glauber@caviumnetworks.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 arch/arm/include/asm/kvm_mmu.h   | 16 ++++++++++++++++
 arch/arm64/include/asm/kvm_mmu.h | 16 ++++++++++++++++
 virt/kvm/arm/vgic/vgic-its.c     | 15 ++++++++-------
 3 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 707a1f06dc5d..f675162663f0 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -309,6 +309,22 @@ static inline unsigned int kvm_get_vmid_bits(void)
 	return 8;
 }
 
+/*
+ * We are not in the kvm->srcu critical section most of the time, so we take
+ * the SRCU read lock here. Since we copy the data from the user page, we
+ * can immediately drop the lock again.
+ */
+static inline int kvm_read_guest_lock(struct kvm *kvm,
+				      gpa_t gpa, void *data, unsigned long len)
+{
+	int srcu_idx = srcu_read_lock(&kvm->srcu);
+	int ret = kvm_read_guest(kvm, gpa, data, len);
+
+	srcu_read_unlock(&kvm->srcu, srcu_idx);
+
+	return ret;
+}
+
 static inline void *kvm_get_hyp_vector(void)
 {
 	return kvm_ksym_ref(__kvm_hyp_vector);
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 082110993647..6128992c2ded 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -360,6 +360,22 @@ static inline unsigned int kvm_get_vmid_bits(void)
 	return (cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR1_VMIDBITS_SHIFT) == 2) ? 16 : 8;
 }
 
+/*
+ * We are not in the kvm->srcu critical section most of the time, so we take
+ * the SRCU read lock here. Since we copy the data from the user page, we
+ * can immediately drop the lock again.
+ */
+static inline int kvm_read_guest_lock(struct kvm *kvm,
+				      gpa_t gpa, void *data, unsigned long len)
+{
+	int srcu_idx = srcu_read_lock(&kvm->srcu);
+	int ret = kvm_read_guest(kvm, gpa, data, len);
+
+	srcu_read_unlock(&kvm->srcu, srcu_idx);
+
+	return ret;
+}
+
 #ifdef CONFIG_KVM_INDIRECT_VECTORS
 /*
  * EL2 vectors can be mapped and rerouted in a number of ways,
diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 51a80b600632..7cb060e01a76 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -281,8 +281,8 @@ static int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq,
 	int ret;
 	unsigned long flags;
 
-	ret = kvm_read_guest(kvm, propbase + irq->intid - GIC_LPI_OFFSET,
-			     &prop, 1);
+	ret = kvm_read_guest_lock(kvm, propbase + irq->intid - GIC_LPI_OFFSET,
+				  &prop, 1);
 
 	if (ret)
 		return ret;
@@ -444,8 +444,9 @@ static int its_sync_lpi_pending_table(struct kvm_vcpu *vcpu)
 		 * this very same byte in the last iteration. Reuse that.
 		 */
 		if (byte_offset != last_byte_offset) {
-			ret = kvm_read_guest(vcpu->kvm, pendbase + byte_offset,
-					     &pendmask, 1);
+			ret = kvm_read_guest_lock(vcpu->kvm,
+						  pendbase + byte_offset,
+						  &pendmask, 1);
 			if (ret) {
 				kfree(intids);
 				return ret;
@@ -789,7 +790,7 @@ static bool vgic_its_check_id(struct vgic_its *its, u64 baser, u32 id,
 		return false;
 
 	/* Each 1st level entry is represented by a 64-bit value. */
-	if (kvm_read_guest(its->dev->kvm,
+	if (kvm_read_guest_lock(its->dev->kvm,
 			   BASER_ADDRESS(baser) + index * sizeof(indirect_ptr),
 			   &indirect_ptr, sizeof(indirect_ptr)))
 		return false;
@@ -1370,8 +1371,8 @@ static void vgic_its_process_commands(struct kvm *kvm, struct vgic_its *its)
 	cbaser = CBASER_ADDRESS(its->cbaser);
 
 	while (its->cwriter != its->creadr) {
-		int ret = kvm_read_guest(kvm, cbaser + its->creadr,
-					 cmd_buf, ITS_CMD_SIZE);
+		int ret = kvm_read_guest_lock(kvm, cbaser + its->creadr,
+					      cmd_buf, ITS_CMD_SIZE);
 		/*
 		 * If kvm_read_guest() fails, this could be due to the guest
 		 * programming a bogus value in CBASER or something else going
-- 
2.14.1

[PATCH 4/4] KVM: arm/arm64: VGIC/ITS save/restore: protect kvm_read_guest() calls

[Andre Przywara]

kvm_read_guest() will eventually look up in kvm_memslots(), which requires
either to hold the kvm->slots_lock or to be inside a kvm->srcu critical
section.
In contrast to x86 and s390 we don't take the SRCU lock on every guest
exit, so we have to do it individually for each kvm_read_guest() call.
Use the newly introduced wrapper for that.

Cc: Stable <stable@vger.kernel.org> # 4.12+
Reported-by: Jan Glauber <jan.glauber@caviumnetworks.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 virt/kvm/arm/vgic/vgic-its.c | 4 ++--
 virt/kvm/arm/vgic/vgic-v3.c  | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 7cb060e01a76..4ed79c939fb4 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -1897,7 +1897,7 @@ static int scan_its_table(struct vgic_its *its, gpa_t base, int size, int esz,
 		int next_offset;
 		size_t byte_offset;
 
-		ret = kvm_read_guest(kvm, gpa, entry, esz);
+		ret = kvm_read_guest_lock(kvm, gpa, entry, esz);
 		if (ret)
 			return ret;
 
@@ -2267,7 +2267,7 @@ static int vgic_its_restore_cte(struct vgic_its *its, gpa_t gpa, int esz)
 	int ret;
 
 	BUG_ON(esz > sizeof(val));
-	ret = kvm_read_guest(kvm, gpa, &val, esz);
+	ret = kvm_read_guest_lock(kvm, gpa, &val, esz);
 	if (ret)
 		return ret;
 	val = le64_to_cpu(val);
diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index c7423f3768e5..bdcf8e7a6161 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -344,7 +344,7 @@ int vgic_v3_lpi_sync_pending_status(struct kvm *kvm, struct vgic_irq *irq)
 	bit_nr = irq->intid % BITS_PER_BYTE;
 	ptr = pendbase + byte_offset;
 
-	ret = kvm_read_guest(kvm, ptr, &val, 1);
+	ret = kvm_read_guest_lock(kvm, ptr, &val, 1);
 	if (ret)
 		return ret;
 
@@ -397,7 +397,7 @@ int vgic_v3_save_pending_tables(struct kvm *kvm)
 		ptr = pendbase + byte_offset;
 
 		if (byte_offset != last_byte_offset) {
-			ret = kvm_read_guest(kvm, ptr, &val, 1);
+			ret = kvm_read_guest_lock(kvm, ptr, &val, 1);
 			if (ret)
 				return ret;
 			last_byte_offset = byte_offset;
-- 
2.14.1

[PATCH 0/4] KVM: arm/arm64: Fix locking issues

[Christoffer Dall]

On Fri, May 11, 2018 at 03:20:11PM +0100, Andre Przywara wrote:
> Jan recently reported lockdep complaints regarding various locks in our
> VGIC emulation [1][2].
> This boiled down to two separate issues:
> - When promoting the vgic_irq->irq_lock to require IRQs being disabled,
>   we forgot to amend some instances of this lock on the way. Also this
>   needs to be applied to dependent locks as well. The first two patches
>   fix that. The patch split is designed to simplify backporting.
>   Those patches have been posted before, I am resending them as part
>   of this series.
> - Calling kvm_read_guest() requires us to be inside an SRCU critical
>   section. On some architectures we are always in it when handling VCPU
>   exits, but on ARM we need to lock it individually. Patches 3 and 4
>   fix that, the split is again made to ease backporting.
>   Each of the hunks fix an indiviual commit, but I refrained from
>   splitting this down into eight patches just to put proper Fixes: tags
>   on it. Eventually those commits are part of one out of two series, I put
>   the respective kernel release version as a tag to the Cc: stable line.
> 
> I couldn't reproduce the full lockdep splat on my setup, but at least
> could show one instance and prove that these patches fixes that.
> 
> 
For the series:

Acked-by: Christoffer Dall <christoffer.dall@arm.com>


Thanks for fixing this,
-Christoffer

[PATCH 0/4] KVM: arm/arm64: Fix locking issues

[Paolo Bonzini]

On 15/05/2018 12:26, Christoffer Dall wrote:
> On Fri, May 11, 2018 at 03:20:11PM +0100, Andre Przywara wrote:
>> Jan recently reported lockdep complaints regarding various locks in our
>> VGIC emulation [1][2].
>> This boiled down to two separate issues:
>> - When promoting the vgic_irq->irq_lock to require IRQs being disabled,
>>   we forgot to amend some instances of this lock on the way. Also this
>>   needs to be applied to dependent locks as well. The first two patches
>>   fix that. The patch split is designed to simplify backporting.
>>   Those patches have been posted before, I am resending them as part
>>   of this series.
>> - Calling kvm_read_guest() requires us to be inside an SRCU critical
>>   section. On some architectures we are always in it when handling VCPU
>>   exits, but on ARM we need to lock it individually. Patches 3 and 4
>>   fix that, the split is again made to ease backporting.
>>   Each of the hunks fix an indiviual commit, but I refrained from
>>   splitting this down into eight patches just to put proper Fixes: tags
>>   on it. Eventually those commits are part of one out of two series, I put
>>   the respective kernel release version as a tag to the Cc: stable line.
>>
>> I couldn't reproduce the full lockdep splat on my setup, but at least
>> could show one instance and prove that these patches fixes that.
>>
>>
> For the series:
> 
> Acked-by: Christoffer Dall <christoffer.dall@arm.com>

Shall I put the patches on their route to Linus?

Thanks,

Paolo

[PATCH 0/4] KVM: arm/arm64: Fix locking issues

[Marc Zyngier]

On 15/05/18 12:35, Paolo Bonzini wrote:
> On 15/05/2018 12:26, Christoffer Dall wrote:
>> On Fri, May 11, 2018 at 03:20:11PM +0100, Andre Przywara wrote:
>>> Jan recently reported lockdep complaints regarding various locks in our
>>> VGIC emulation [1][2].
>>> This boiled down to two separate issues:
>>> - When promoting the vgic_irq->irq_lock to require IRQs being disabled,
>>>   we forgot to amend some instances of this lock on the way. Also this
>>>   needs to be applied to dependent locks as well. The first two patches
>>>   fix that. The patch split is designed to simplify backporting.
>>>   Those patches have been posted before, I am resending them as part
>>>   of this series.
>>> - Calling kvm_read_guest() requires us to be inside an SRCU critical
>>>   section. On some architectures we are always in it when handling VCPU
>>>   exits, but on ARM we need to lock it individually. Patches 3 and 4
>>>   fix that, the split is again made to ease backporting.
>>>   Each of the hunks fix an indiviual commit, but I refrained from
>>>   splitting this down into eight patches just to put proper Fixes: tags
>>>   on it. Eventually those commits are part of one out of two series, I put
>>>   the respective kernel release version as a tag to the Cc: stable line.
>>>
>>> I couldn't reproduce the full lockdep splat on my setup, but at least
>>> could show one instance and prove that these patches fixes that.
>>>
>>>
>> For the series:
>>
>> Acked-by: Christoffer Dall <christoffer.dall@arm.com>
> 
> Shall I put the patches on their route to Linus?
If you're about to send something, yes please (saves me having to send
you a pull request). In that case, please add my

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

to the whole series.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

[PATCH 0/4] KVM: arm/arm64: Fix locking issues

[Paolo Bonzini]

On 15/05/2018 13:54, Marc Zyngier wrote:
> On 15/05/18 12:35, Paolo Bonzini wrote:
>> On 15/05/2018 12:26, Christoffer Dall wrote:
>>> On Fri, May 11, 2018 at 03:20:11PM +0100, Andre Przywara wrote:
>>>> Jan recently reported lockdep complaints regarding various locks in our
>>>> VGIC emulation [1][2].
>>>> This boiled down to two separate issues:
>>>> - When promoting the vgic_irq->irq_lock to require IRQs being disabled,
>>>>   we forgot to amend some instances of this lock on the way. Also this
>>>>   needs to be applied to dependent locks as well. The first two patches
>>>>   fix that. The patch split is designed to simplify backporting.
>>>>   Those patches have been posted before, I am resending them as part
>>>>   of this series.
>>>> - Calling kvm_read_guest() requires us to be inside an SRCU critical
>>>>   section. On some architectures we are always in it when handling VCPU
>>>>   exits, but on ARM we need to lock it individually. Patches 3 and 4
>>>>   fix that, the split is again made to ease backporting.
>>>>   Each of the hunks fix an indiviual commit, but I refrained from
>>>>   splitting this down into eight patches just to put proper Fixes: tags
>>>>   on it. Eventually those commits are part of one out of two series, I put
>>>>   the respective kernel release version as a tag to the Cc: stable line.
>>>>
>>>> I couldn't reproduce the full lockdep splat on my setup, but at least
>>>> could show one instance and prove that these patches fixes that.
>>>>
>>>>
>>> For the series:
>>>
>>> Acked-by: Christoffer Dall <christoffer.dall@arm.com>
>>
>> Shall I put the patches on their route to Linus?
> If you're about to send something, yes please (saves me having to send
> you a pull request). In that case, please add my

Yes, I do - and I was keeping my eyes on this series anyway.

Thanks,

Paolo

> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
> 
> to the whole series.
> 
> Thanks,
> 
> 	M.
>