xen/pci: Add xen_[find|register|unregister]_device_domain_owner functions.

When the Xen PCI backend is told to enable or disable MSI/MSI-X functions,
the initial domain performs these operations. The initial domain needs
to know which domain (guest) is going to use the PCI device so when it
makes the appropiate hypercall to retrieve the MSI/MSI-X vector it will
also assign the PCI device to the appropiate domain (guest).

This boils down to us needing a mechanism to find, set and unset the domain
id that will be using the device.

[v2: EXPORT_SYMBOL -> EXPORT_SYMBOL_GPL.]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/arch/x86/include/asm/xen/pci.h b/arch/x86/include/asm/xen/pci.h
index aa8620989162..4fbda9a3f339 100644
--- a/arch/x86/include/asm/xen/pci.h
+++ b/arch/x86/include/asm/xen/pci.h
@@ -15,10 +15,26 @@ static inline int pci_xen_hvm_init(void)
 #endif
 #if defined(CONFIG_XEN_DOM0)
 void __init xen_setup_pirqs(void);
+int xen_find_device_domain_owner(struct pci_dev *dev);
+int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain);
+int xen_unregister_device_domain_owner(struct pci_dev *dev);
 #else
 static inline void __init xen_setup_pirqs(void)
 {
 }
+static inline int xen_find_device_domain_owner(struct pci_dev *dev)
+{
+	return -1;
+}
+static inline int xen_register_device_domain_owner(struct pci_dev *dev,
+						   uint16_t domain)
+{
+	return -1;
+}
+static inline int xen_unregister_device_domain_owner(struct pci_dev *dev)
+{
+	return -1;
+}
 #endif
 
 #if defined(CONFIG_PCI_MSI)