x86/MSI: cleanup to prepare for multi-vector MSI

The major aspect being the removal of the overload of the MSI entry's
mask_base field for MSI purposes - a proper union is being installed
instead, tracking both the config space position needed and the number
of vectors used (which is going to be 1 until the actual multi-vector
MSI patches arrive).

It also corrects misleading information from debug key 'M': When
msi_get_mask_bit() returns a negative value, there's no mask bit, and
hence output shouldn't give the impression there is.

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

1 files changed, 4 insertions, 0 deletions

diff --git a/xen/include/asm-x86/msi.h b/xen/include/asm-x86/msi.h
index 6fe67dc145..d288cfcaa2 100644
--- a/xen/include/asm-x86/msi.h
+++ b/xen/include/asm-x86/msi.h
@@ -100,6 +100,10 @@ struct msi_desc {
 
 	union {
 		void __iomem *mask_base;/* va for the entry in mask table */
+		struct {
+			unsigned int nvec;/* number of vectors            */
+			unsigned int mpos;/* location of mask register    */
+		} msi;
 		unsigned int hpet_id;   /* HPET (dev is NULL)             */
 	};
 	struct pci_dev *dev;