x86-64/MMCFG: pass down firmware (ACPI) reservation status of used memory space

Reserving the MMCFG address range(s) in E820 is specified to only be
optional for the firmware to do. The requirement is to have them
reserved in ACPI resources. Those, however, aren't directly visible to
Xen as they require the ACPI interpreter to be active. Thus, if a
range isn't reserved in E820, we should not completely disable use of
MMCFG on the respective bus range, but rather keep it disabled until
Dom0 can pass down information on the ACPI reservation status (though
a new physdevop hypercall).

Signed-off-by: Jan Beulich <jbeulich@novell.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/xen/arch/x86/physdev.c b/xen/arch/x86/physdev.c
index 4b0f4031e6..35fbbeb348 100644
--- a/xen/arch/x86/physdev.c
+++ b/xen/arch/x86/physdev.c
@@ -21,6 +21,10 @@ int physdev_map_pirq(domid_t, int type, int *index, int *pirq_p,
                      struct msi_info *);
 int physdev_unmap_pirq(domid_t, int pirq);
 
+#ifdef CONFIG_X86_64
+#include "x86_64/mmconfig.h"
+#endif
+
 #ifndef COMPAT
 typedef long ret_t;
 
@@ -522,6 +526,24 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE(void) arg)
         break;
     }
 
+#ifdef __x86_64__
+    case PHYSDEVOP_pci_mmcfg_reserved: {
+        struct physdev_pci_mmcfg_reserved info;
+
+        ret = -EPERM;
+        if ( !IS_PRIV(current->domain) )
+            break;
+
+        ret = -EFAULT;
+        if ( copy_from_guest(&info, arg, 1) )
+            break;
+
+        ret = pci_mmcfg_reserved(info.address, info.segment,
+                                 info.start_bus, info.end_bus, info.flags);
+        break;
+    }
+#endif
+
     case PHYSDEVOP_restore_msi: {
         struct physdev_restore_msi restore_msi;
         struct pci_dev *pdev;