xen: support GSI -> pirq remapping in PV on HVM guests

Disable pcifront when running on HVM: it is meant to be used with pv
guests that don't have PCI bus.

Use acpi_register_gsi_xen_hvm to remap GSIs into pirqs.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

2 files changed, 21 insertions, 0 deletions

diff --git a/arch/x86/include/asm/xen/pci.h b/arch/x86/include/asm/xen/pci.h
index 449c82f71677..f89a42aff284 100644
--- a/arch/x86/include/asm/xen/pci.h
+++ b/arch/x86/include/asm/xen/pci.h
@@ -3,10 +3,15 @@
 
 #if defined(CONFIG_PCI_XEN)
 extern int __init pci_xen_init(void);
+extern int __init pci_xen_hvm_init(void);
 #define pci_xen 1
 #else
 #define pci_xen 0
 #define pci_xen_init (0)
+static inline int pci_xen_hvm_init(void)
+{
+        return -1;
+}
 #endif
 
 #if defined(CONFIG_PCI_MSI)
diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 3a4ab0b4dcca..d5284c491aef 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -14,6 +14,7 @@
 
 #include <asm/xen/hypervisor.h>
 
+#include <xen/features.h>
 #include <xen/events.h>
 #include <asm/xen/pci.h>
 
@@ -184,3 +185,18 @@ int __init pci_xen_init(void)
 #endif
         return 0;
 }
+
+int __init pci_xen_hvm_init(void)
+{
+        if (!xen_feature(XENFEAT_hvm_pirqs))
+                return 0;
+
+#ifdef CONFIG_ACPI
+        /*
+         * We don't want to change the actual ACPI delivery model,
+         * just how GSIs get registered.
+         */
+        __acpi_register_gsi = acpi_register_gsi_xen_hvm;
+#endif
+        return 0;
+}