[Xen-devel] [PATCH 1/4] xen/pciback: Check PF instead of VF for PCI_COMMAND_MEMORY

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

c/s 408fb0e5aa7fda0059db282ff58c3b2a4278baa0
"xen/pciback: Don't allow MSI-X ops if PCI_COMMAND_MEMORY is not set."
would check the device for PCI_COMMAND_MEMORY which is great.
Except that VF devices are unique - for example they have no
legacy interrupts, and also any writes to PCI_COMMAND_MEMORY
are silently ignored (by the hardware).

CC: stable@xxxxxxxxxxxxxxx
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 drivers/xen/xen-pciback/pciback_ops.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/xen-pciback/pciback_ops.c 
b/drivers/xen/xen-pciback/pciback_ops.c
index 73dafdc..8c86a53 100644
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -213,6 +213,7 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
        int i, result;
        struct msix_entry *entries;
        u16 cmd;
+       struct pci_dev *phys_dev;
 
        if (unlikely(verbose_request))
                printk(KERN_DEBUG DRV_NAME ": %s: enable MSI-X\n",
@@ -227,8 +228,10 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
        /*
         * PCI_COMMAND_MEMORY must be enabled, otherwise we may not be able
         * to access the BARs where the MSI-X entries reside.
+        * But VF devices are unique in which the PF needs to be checked.
         */
-       pci_read_config_word(dev, PCI_COMMAND, &cmd);
+       phys_dev = pci_physfn(dev);
+       pci_read_config_word(phys_dev, PCI_COMMAND, &cmd);
        if (dev->msi_enabled || !(cmd & PCI_COMMAND_MEMORY))
                return -ENXIO;
 
-- 
2.1.0


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