xen/x86/PCI: Add support for the Xen PCI subsystem

The frontend stub lives in arch/x86/pci/xen.c, alongside other
sub-arch PCI init code (e.g. olpc.c).

It provides a mechanism for Xen PCI frontend to setup/destroy
legacy interrupts, MSI/MSI-X, and PCI configuration operations.

[ Impact: add core of Xen PCI support ]
[ v2: Removed the IOMMU code and only focusing on PCI.]
[ v3: removed usage of pci_scan_all_fns as that does not exist]
[ v4: introduced pci_xen value to fix compile warnings]
[ v5: squished fixes+features in one patch, changed Reviewed-by to Ccs]
[ v7: added Acked-by]
Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Qing He <qing.he@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org

1 files changed, 30 insertions, 2 deletions

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index cd504092299b..7016a734257c 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -582,7 +582,9 @@ int xen_allocate_pirq(unsigned gsi, int shareable, char *name)
                 goto out;       /* XXX need refcount? */
         }
 
-        if (identity_mapped_irq(gsi)) {
+        /* If we are a PV guest, we don't have GSIs (no ACPI passed). Therefore
+         * we are using the !xen_initial_domain() to drop in the function.*/
+        if (identity_mapped_irq(gsi) || !xen_initial_domain()) {
                 irq = gsi;
                 irq_to_desc_alloc_node(irq, 0);
                 dynamic_irq_init(irq);
@@ -593,7 +595,13 @@ int xen_allocate_pirq(unsigned gsi, int shareable, char *name)
                                       handle_level_irq, name);
 
         irq_op.irq = irq;
-        if (HYPERVISOR_physdev_op(PHYSDEVOP_alloc_irq_vector, &irq_op)) {
+        irq_op.vector = 0;
+
+        /* Only the privileged domain can do this. For non-priv, the pcifront
+         * driver provides a PCI bus that does the call to do exactly
+         * this in the priv domain. */
+        if (xen_initial_domain() &&
+            HYPERVISOR_physdev_op(PHYSDEVOP_alloc_irq_vector, &irq_op)) {
                 dynamic_irq_cleanup(irq);
                 irq = -ENOSPC;
                 goto out;
@@ -608,6 +616,26 @@ out:
         return irq;
 }
 
+int xen_destroy_irq(int irq)
+{
+        struct irq_desc *desc;
+        int rc = -ENOENT;
+
+        spin_lock(&irq_mapping_update_lock);
+
+        desc = irq_to_desc(irq);
+        if (!desc)
+                goto out;
+
+        irq_info[irq] = mk_unbound_info();
+
+        dynamic_irq_cleanup(irq);
+
+out:
+        spin_unlock(&irq_mapping_update_lock);
+        return rc;
+}
+
 int xen_vector_from_irq(unsigned irq)
 {
         return vector_from_irq(irq);