FAILED: patch "[PATCH] iommu/vt-d: Don't queue_iova() if there is no flush queue" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From effa467870c7612012885df4e246bdb8ffd8e44c Mon Sep 17 00:00:00 2001
From: Dmitry Safonov <[email protected]>
Date: Tue, 16 Jul 2019 22:38:05 +0100
Subject: [PATCH] iommu/vt-d: Don't queue_iova() if there is no flush queue

Intel VT-d driver was reworked to use common deferred flushing implementation. Previously there was one global per-cpu flush queue, afterwards - one per domain.

Before deferring a flush, the queue should be allocated and initialized.

Currently only domains with IOMMU_DOMAIN_DMA type initialize their flush queue. It's probably worth to init it for static or unmanaged domains too, but it may be arguable - I'm leaving it to iommu folks.

Prevent queuing an iova flush if the domain doesn't have a queue. The defensive check seems to be worth to keep even if queue would be initialized for all kinds of domains. And is easy backportable.

On 4.19.43 stable kernel it has a user-visible effect: previously for devices in si domain there were crashes, on sata devices:

 BUG: spinlock bad magic on CPU#6, swapper/0/1
  lock: 0xffff88844f582008, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
 CPU: 6 PID: 1 Comm: swapper/0 Not tainted 4.19.43 #1
 Call Trace:
  <IRQ>
  dump_stack+0x61/0x7e
  spin_bug+0x9d/0xa3
  do_raw_spin_lock+0x22/0x8e
  _raw_spin_lock_irqsave+0x32/0x3a
  queue_iova+0x45/0x115
  intel_unmap+0x107/0x113
  intel_unmap_sg+0x6b/0x76
  __ata_qc_complete+0x7f/0x103
  ata_qc_complete+0x9b/0x26a
  ata_qc_complete_multiple+0xd0/0xe3
  ahci_handle_port_interrupt+0x3ee/0x48a
  ahci_handle_port_intr+0x73/0xa9
  ahci_single_level_irq_intr+0x40/0x60
  __handle_irq_event_percpu+0x7f/0x19a
  handle_irq_event_percpu+0x32/0x72
  handle_irq_event+0x38/0x56
  handle_edge_irq+0x102/0x121
  handle_irq+0x147/0x15c
  do_IRQ+0x66/0xf2
  common_interrupt+0xf/0xf
 RIP: 0010:__do_softirq+0x8c/0x2df

The same for usb devices that use ehci-pci:

 BUG: spinlock bad magic on CPU#0, swapper/0/1
  lock: 0xffff88844f402008, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.43 #4
 Call Trace:
  <IRQ>
  dump_stack+0x61/0x7e
  spin_bug+0x9d/0xa3
  do_raw_spin_lock+0x22/0x8e
  _raw_spin_lock_irqsave+0x32/0x3a
  queue_iova+0x77/0x145
  intel_unmap+0x107/0x113
  intel_unmap_page+0xe/0x10
  usb_hcd_unmap_urb_setup_for_dma+0x53/0x9d
  usb_hcd_unmap_urb_for_dma+0x17/0x100
  unmap_urb_for_dma+0x22/0x24
  __usb_hcd_giveback_urb+0x51/0xc3
  usb_giveback_urb_bh+0x97/0xde
  tasklet_action_common.isra.4+0x5f/0xa1
  tasklet_action+0x2d/0x30
  __do_softirq+0x138/0x2df
  irq_exit+0x7d/0x8b
  smp_apic_timer_interrupt+0x10f/0x151
  apic_timer_interrupt+0xf/0x20
  </IRQ>
 RIP: 0010:_raw_spin_unlock_irqrestore+0x17/0x39

index 9b1d62d03370..72c6d647bec9 100644
@@ -3561,7 +3561,8 @@ static void intel_unmap(struct device *dev, dma_addr_t dev_addr, size_t size)
 
 	freelist = domain_unmap(domain, start_pfn, last_pfn);
 
-	if (intel_iommu_strict || (pdev && pdev->untrusted)) {
+	if (intel_iommu_strict || (pdev && pdev->untrusted) ||
+			!has_iova_flush_queue(&domain->iovad)) {
 		iommu_flush_iotlb_psi(iommu, domain, start_pfn,
 				      nrpages, !freelist, 0);
 		/* free iova */

index d499b2621239..8413ae54904a 100644
@@ -54,9 +54,14 @@ init_iova_domain(struct iova_domain *iovad, unsigned long granule,
 }
 EXPORT_SYMBOL_GPL(init_iova_domain);
 
+bool has_iova_flush_queue(struct iova_domain *iovad)
+{
+	return !!iovad->fq;
+}
+
 static void free_iova_flush_queue(struct iova_domain *iovad)
 {
-	if (!iovad->fq)
+	if (!has_iova_flush_queue(iovad))
 		return;
 
 	if (timer_pending(&iovad->fq_timer))

@@ -74,13 +79,14 @@ static void free_iova_flush_queue(struct iova_domain *iovad)
 int init_iova_flush_queue(struct iova_domain *iovad,
 			  iova_flush_cb flush_cb, iova_entry_dtor entry_dtor)
 {
+	struct iova_fq __percpu *queue;
 	int cpu;
 
 	atomic64_set(&iovad->fq_flush_start_cnt,  0);
 	atomic64_set(&iovad->fq_flush_finish_cnt, 0);
 
-	iovad->fq = alloc_percpu(struct iova_fq);
-	if (!iovad->fq)
+	queue = alloc_percpu(struct iova_fq);
+	if (!queue)
 		return -ENOMEM;
 
 	iovad->flush_cb   = flush_cb;

@@ -89,13 +95,17 @@ int init_iova_flush_queue(struct iova_domain *iovad,
 	for_each_possible_cpu(cpu) {
 		struct iova_fq *fq;
 
-		fq = per_cpu_ptr(iovad->fq, cpu);
+		fq = per_cpu_ptr(queue, cpu);
 		fq->head = 0;
 		fq->tail = 0;
 
 		spin_lock_init(&fq->lock);
 	}
 
+	smp_wmb();
+
+	iovad->fq = queue;
+
 	timer_setup(&iovad->fq_timer, fq_flush_timeout, 0);
 	atomic_set(&iovad->fq_timer_on, 0);
 

index 781b96ac706f..cd0f1de901a8 100644
@@ -155,6 +155,7 @@ struct iova *reserve_iova(struct iova_domain *iovad, unsigned long pfn_lo,
 void copy_reserved_iova(struct iova_domain *from, struct iova_domain *to);
 void init_iova_domain(struct iova_domain *iovad, unsigned long granule,
 	unsigned long start_pfn);
+bool has_iova_flush_queue(struct iova_domain *iovad);
 int init_iova_flush_queue(struct iova_domain *iovad,
 			  iova_flush_cb flush_cb, iova_entry_dtor entry_dtor);
 struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn);

@@ -235,6 +236,11 @@ static inline void init_iova_domain(struct iova_domain *iovad,
 {
 }
 
+bool has_iova_flush_queue(struct iova_domain *iovad)
+{
+	return false;
+}
+
 static inline int init_iova_flush_queue(struct iova_domain *iovad,
 					iova_flush_cb flush_cb,
 					iova_entry_dtor entry_dtor)

Hi Greg,

It's not needed for v4.9 stable tree [as pointed by tag's comment line]:

If there is any better way to inform where a commit should be backported, please let me know.

I'll send v4.19 -stable patch shortly..
And will prepare v4.14 patch (as we don't have v4.14 release, I need to actually port it).

Thanks,
Dmitry

That is correct, as this commit (13cf01744608 ("iommu/vt-d: Make use of iova deferred flushing")) did originally show up in 4.14:

	$ git describe --contains 13cf01744608
v4.14-rc1~72^2^14~3

But, that commit ended up in a stable release, the 4.9.104 release.

Oh. nope, crap, my fault, my scripts pick up the fact that we refer to commit 13cf01744608 in a 4.9 commit, but only the fact that it is _not_ in the 4.9.y tree.

Sorry, my fault, scripts are only so good at times.

Thanks for doing the backport, and sorry for the 4.9.y noise, you were right here, my scripts were wrong.

greg k-h