PCI: handle Virtual Function ATS enabling

The SR-IOV spec requires that the Smallest Translation Unit and
the Invalidate Queue Depth fields in the Virtual Function ATS
capability are hardwired to 0. If a function is a Virtual Function,
then and set its Physical Function's STU before enabling the ATS.

Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

2 files changed, 55 insertions, 15 deletions

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 0a7a1b40286f..415140499ffb 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -491,10 +491,10 @@ found:
 
         if (pdev)
                 iov->dev = pci_dev_get(pdev);
-        else {
+        else
                 iov->dev = dev;
-                mutex_init(&iov->lock);
-        }
+
+        mutex_init(&iov->lock);
 
         dev->sriov = iov;
         dev->is_physfn = 1;
@@ -514,11 +514,11 @@ static void sriov_release(struct pci_dev *dev)
 {
         BUG_ON(dev->sriov->nr_virtfn);
 
-        if (dev == dev->sriov->dev)
-                mutex_destroy(&dev->sriov->lock);
-        else
+        if (dev != dev->sriov->dev)
                 pci_dev_put(dev->sriov->dev);
 
+        mutex_destroy(&dev->sriov->lock);
+
         kfree(dev->sriov);
         dev->sriov = NULL;
 }
@@ -723,19 +723,40 @@ int pci_enable_ats(struct pci_dev *dev, int ps)
         int rc;
         u16 ctrl;
 
-        BUG_ON(dev->ats);
+        BUG_ON(dev->ats && dev->ats->is_enabled);
 
         if (ps < PCI_ATS_MIN_STU)
                 return -EINVAL;
 
-        rc = ats_alloc_one(dev, ps);
-        if (rc)
-                return rc;
+        if (dev->is_physfn || dev->is_virtfn) {
+                struct pci_dev *pdev = dev->is_physfn ? dev : dev->physfn;
+
+                mutex_lock(&pdev->sriov->lock);
+                if (pdev->ats)
+                        rc = pdev->ats->stu == ps ? 0 : -EINVAL;
+                else
+                        rc = ats_alloc_one(pdev, ps);
+
+                if (!rc)
+                        pdev->ats->ref_cnt++;
+                mutex_unlock(&pdev->sriov->lock);
+                if (rc)
+                        return rc;
+        }
+
+        if (!dev->is_physfn) {
+                rc = ats_alloc_one(dev, ps);
+                if (rc)
+                        return rc;
+        }
 
         ctrl = PCI_ATS_CTRL_ENABLE;
-        ctrl |= PCI_ATS_CTRL_STU(ps - PCI_ATS_MIN_STU);
+        if (!dev->is_virtfn)
+                ctrl |= PCI_ATS_CTRL_STU(ps - PCI_ATS_MIN_STU);
         pci_write_config_word(dev, dev->ats->pos + PCI_ATS_CTRL, ctrl);
 
+        dev->ats->is_enabled = 1;
+
         return 0;
 }
 
@@ -747,13 +768,26 @@ void pci_disable_ats(struct pci_dev *dev)
 {
         u16 ctrl;
 
-        BUG_ON(!dev->ats);
+        BUG_ON(!dev->ats || !dev->ats->is_enabled);
 
         pci_read_config_word(dev, dev->ats->pos + PCI_ATS_CTRL, &ctrl);
         ctrl &= ~PCI_ATS_CTRL_ENABLE;
         pci_write_config_word(dev, dev->ats->pos + PCI_ATS_CTRL, ctrl);
 
-        ats_free_one(dev);
+        dev->ats->is_enabled = 0;
+
+        if (dev->is_physfn || dev->is_virtfn) {
+                struct pci_dev *pdev = dev->is_physfn ? dev : dev->physfn;
+
+                mutex_lock(&pdev->sriov->lock);
+                pdev->ats->ref_cnt--;
+                if (!pdev->ats->ref_cnt)
+                        ats_free_one(pdev);
+                mutex_unlock(&pdev->sriov->lock);
+        }
+
+        if (!dev->is_physfn)
+                ats_free_one(dev);
 }
 
 /**
@@ -765,13 +799,17 @@ void pci_disable_ats(struct pci_dev *dev)
  * The ATS spec uses 0 in the Invalidate Queue Depth field to
  * indicate that the function can accept 32 Invalidate Request.
  * But here we use the `real' values (i.e. 1~32) for the Queue
- * Depth.
+ * Depth; and 0 indicates the function shares the Queue with
+ * other functions (doesn't exclusively own a Queue).
  */
 int pci_ats_queue_depth(struct pci_dev *dev)
 {
         int pos;
         u16 cap;
 
+        if (dev->is_virtfn)
+                return 0;
+
         if (dev->ats)
                 return dev->ats->qdep;
 
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 3c2ec64f78e9..f73bcbedf37c 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -234,6 +234,8 @@ struct pci_ats {
         int pos;        /* capability position */
         int stu;        /* Smallest Translation Unit */
         int qdep;       /* Invalidate Queue Depth */
+        int ref_cnt;    /* Physical Function reference count */
+        int is_enabled:1;       /* Enable bit is set */
 };
 
 #ifdef CONFIG_PCI_IOV
@@ -255,7 +257,7 @@ extern int pci_ats_queue_depth(struct pci_dev *dev);
  */
 static inline int pci_ats_enabled(struct pci_dev *dev)
 {
-        return !!dev->ats;
+        return dev->ats && dev->ats->is_enabled;
 }
 #else
 static inline int pci_iov_init(struct pci_dev *dev)