[PATCH] xen-pciback: Consider MSI-X enabled only when MASKALL bit is cleared

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

Linux enables MSI-X before disabling INTx, but keeps MSI-X masked until
the table is filled. Then it disables INTx just before clearing MASKALL
bit. Currently this approach is rejected by xen-pciback.
Allow setting PCI_MSIX_FLAGS_ENABLE while INTx is still enabled as long
as PCI_MSIX_FLAGS_MASKALL is set too.

Fixes: 5e29500eba2a ("xen-pciback: Allow setting PCI_MSIX_FLAGS_MASKALL too")
Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
---
 drivers/xen/xen-pciback/conf_space.c            | 2 +-
 drivers/xen/xen-pciback/conf_space_capability.c | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/xen-pciback/conf_space.c 
b/drivers/xen/xen-pciback/conf_space.c
index 059de92aea7d..e8923bffc175 100644
--- a/drivers/xen/xen-pciback/conf_space.c
+++ b/drivers/xen/xen-pciback/conf_space.c
@@ -313,7 +313,7 @@ int xen_pcibk_get_interrupt_type(struct pci_dev *dev)
                                &val);
                if (err)
                        return err;
-               if (val & PCI_MSIX_FLAGS_ENABLE)
+               if (val & PCI_MSIX_FLAGS_ENABLE && !(val & 
PCI_MSIX_FLAGS_MASKALL))
                        ret |= INTERRUPT_TYPE_MSIX;
        }
        return ret ?: INTERRUPT_TYPE_NONE;
diff --git a/drivers/xen/xen-pciback/conf_space_capability.c 
b/drivers/xen/xen-pciback/conf_space_capability.c
index 097316a74126..5c851f916ebc 100644
--- a/drivers/xen/xen-pciback/conf_space_capability.c
+++ b/drivers/xen/xen-pciback/conf_space_capability.c
@@ -242,6 +242,10 @@ static int msi_msix_flags_write(struct pci_dev *dev, int 
offset, u16 new_value,
                if (int_type == INTERRUPT_TYPE_NONE ||
                    int_type == field_config->int_type)
                        goto write;
+               if (int_type == INTERRUPT_TYPE_INTX &&
+                   field_config->int_type == INTERRUPT_TYPE_MSIX &&
+                   (new_value & PCI_MSIX_FLAGS_MASKALL))
+                       goto write;
                return PCIBIOS_SET_FAILED;
        }
 
-- 
2.37.3