@@ -212,6 +212,7 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
struct xen_pcibk_dev_data *dev_data;
int i, result;
struct msix_entry *entries;
+ u16 cmd;
if (unlikely(verbose_request))
printk(KERN_DEBUG DRV_NAME ": %s: enable MSI-X\n",
@@ -223,7 +224,12 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
if (dev->msix_enabled)
return -EALREADY;
- if (dev->msi_enabled)
+ /*
+ * PCI_COMMAND_MEMORY must be enabled, otherwise we may not be able
+ * to access the BARs where the MSI-X entries reside.
+ */
+ pci_read_config_word(dev, PCI_COMMAND, &cmd);
+ if (dev->msi_enabled || !(cmd & PCI_COMMAND_MEMORY))
return -ENXIO;
entries = kmalloc(op->value * sizeof(*entries), GFP_KERNEL);
This is a note to let you know that I have just added a patch titled xen/pciback: Don't allow MSI-X ops if PCI_COMMAND_MEMORY is not set. to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt23. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ---8<------------------------------------------------------------ From f7fcac9f03f6a42a5e1df1d29bbc851a976a2ab9 Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Date: Mon, 2 Nov 2015 18:13:27 -0500 Subject: xen/pciback: Don't allow MSI-X ops if PCI_COMMAND_MEMORY is not set. commit 408fb0e5aa7fda0059db282ff58c3b2a4278baa0 upstream. commit f598282f51 ("PCI: Fix the NIU MSI-X problem in a better way") teaches us that dealing with MSI-X can be troublesome. Further checks in the MSI-X architecture shows that if the PCI_COMMAND_MEMORY bit is turned of in the PCI_COMMAND we may not be able to access the BAR (since they are memory regions). Since the MSI-X tables are located in there.. that can lead to us causing PCIe errors. Inhibit us performing any operation on the MSI-X unless the MEMORY bit is set. Note that Xen hypervisor with: "x86/MSI-X: access MSI-X table only after having enabled MSI-X" will return: xen_pciback: 0000:0a:00.1: error -6 enabling MSI-X for guest 3! When the generic MSI code tries to setup the PIRQ without MEMORY bit set. Which means with later versions of Xen (4.6) this patch is not neccessary. This is part of XSA-157 Reviewed-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/xen/xen-pciback/pciback_ops.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)