Patch "PCI: Set SR-IOV NumVFs to zero after enumeration" has been added to the 4.3-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    PCI: Set SR-IOV NumVFs to zero after enumeration

to the 4.3-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pci-set-sr-iov-numvfs-to-zero-after-enumeration.patch
and it can be found in the queue-4.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ea9a8854161d9580cfabe011c0ae296ecc0e1d4f Mon Sep 17 00:00:00 2001
From: Alexander Duyck <aduyck@mirantis.com>
Date: Thu, 29 Oct 2015 16:20:50 -0500
Subject: PCI: Set SR-IOV NumVFs to zero after enumeration

From: Alexander Duyck <aduyck@mirantis.com>

commit ea9a8854161d9580cfabe011c0ae296ecc0e1d4f upstream.

The enumeration path should leave NumVFs set to zero.  But after
4449f079722c ("PCI: Calculate maximum number of buses required for VFs"),
we call virtfn_max_buses() in the enumeration path, which changes NumVFs.
This NumVFs change is visible via lspci and sysfs until a driver enables
SR-IOV.

Iterate from TotalVFs down to zero so NumVFs is zero when we're finished
computing the maximum number of buses.  Validate offset and stride in
the loop, so we can test it at every possible NumVFs setting.  Rename
virtfn_max_buses() to compute_max_vf_buses() to hint that it does have a
side effect of updating iov->max_VF_buses.

[bhelgaas: changelog, rename, allow numVF==1 && stride==0, rework loop,
reverse sense of error path]
Fixes: 4449f079722c ("PCI: Calculate maximum number of buses required for VFs")
Based-on-patch-by: Ethan Zhao <ethan.zhao@oracle.com>
Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/pci/iov.c |   41 ++++++++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 19 deletions(-)

--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -54,24 +54,29 @@ static inline void pci_iov_set_numvfs(st
  * The PF consumes one bus number.  NumVFs, First VF Offset, and VF Stride
  * determine how many additional bus numbers will be consumed by VFs.
  *
- * Iterate over all valid NumVFs and calculate the maximum number of bus
- * numbers that could ever be required.
+ * Iterate over all valid NumVFs, validate offset and stride, and calculate
+ * the maximum number of bus numbers that could ever be required.
  */
-static inline u8 virtfn_max_buses(struct pci_dev *dev)
+static int compute_max_vf_buses(struct pci_dev *dev)
 {
 	struct pci_sriov *iov = dev->sriov;
-	int nr_virtfn;
-	u8 max = 0;
-	int busnr;
+	int nr_virtfn, busnr, rc = 0;
 
-	for (nr_virtfn = 1; nr_virtfn <= iov->total_VFs; nr_virtfn++) {
+	for (nr_virtfn = iov->total_VFs; nr_virtfn; nr_virtfn--) {
 		pci_iov_set_numvfs(dev, nr_virtfn);
+		if (!iov->offset || (nr_virtfn > 1 && !iov->stride)) {
+			rc = -EIO;
+			goto out;
+		}
+
 		busnr = pci_iov_virtfn_bus(dev, nr_virtfn - 1);
-		if (busnr > max)
-			max = busnr;
+		if (busnr > iov->max_VF_buses)
+			iov->max_VF_buses = busnr;
 	}
 
-	return max;
+out:
+	pci_iov_set_numvfs(dev, 0);
+	return rc;
 }
 
 static struct pci_bus *virtfn_add_bus(struct pci_bus *bus, int busnr)
@@ -384,7 +389,7 @@ static int sriov_init(struct pci_dev *de
 	int rc;
 	int nres;
 	u32 pgsz;
-	u16 ctrl, total, offset, stride;
+	u16 ctrl, total;
 	struct pci_sriov *iov;
 	struct resource *res;
 	struct pci_dev *pdev;
@@ -414,11 +419,6 @@ static int sriov_init(struct pci_dev *de
 
 found:
 	pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, ctrl);
-	pci_write_config_word(dev, pos + PCI_SRIOV_NUM_VF, 0);
-	pci_read_config_word(dev, pos + PCI_SRIOV_VF_OFFSET, &offset);
-	pci_read_config_word(dev, pos + PCI_SRIOV_VF_STRIDE, &stride);
-	if (!offset || (total > 1 && !stride))
-		return -EIO;
 
 	pci_read_config_dword(dev, pos + PCI_SRIOV_SUP_PGSIZE, &pgsz);
 	i = PAGE_SHIFT > 12 ? PAGE_SHIFT - 12 : 0;
@@ -456,8 +456,6 @@ found:
 	iov->nres = nres;
 	iov->ctrl = ctrl;
 	iov->total_VFs = total;
-	iov->offset = offset;
-	iov->stride = stride;
 	iov->pgsz = pgsz;
 	iov->self = dev;
 	pci_read_config_dword(dev, pos + PCI_SRIOV_CAP, &iov->cap);
@@ -474,10 +472,15 @@ found:
 
 	dev->sriov = iov;
 	dev->is_physfn = 1;
-	iov->max_VF_buses = virtfn_max_buses(dev);
+	rc = compute_max_vf_buses(dev);
+	if (rc)
+		goto fail_max_buses;
 
 	return 0;
 
+fail_max_buses:
+	dev->sriov = NULL;
+	dev->is_physfn = 0;
 failed:
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
 		res = &dev->resource[i + PCI_IOV_RESOURCES];


Patches currently in stable-queue which might be from aduyck@mirantis.com are

queue-4.3/pci-set-sr-iov-numvfs-to-zero-after-enumeration.patch