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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2015-11-02 18:13:27 -0500
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2015-12-18 10:48:39 -0500
commit408fb0e5aa7fda0059db282ff58c3b2a4278baa0 (patch)
parent7cfb905b9638982862f0331b36ccaaca5d383b49 (diff)
xen/pciback: Don't allow MSI-X ops if PCI_COMMAND_MEMORY is not set.
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 CC: stable@vger.kernel.org Reviewed-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
index 4ee5fc080483..73dafdc494aa 100644
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -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);