iommu/amd: Fix interrupt remapping when disable guest_mode

Pass-through devices to VM guest can get updated IRQ affinity
information via irq_set_affinity() when not running in guest mode.
Currently, AMD IOMMU driver in GA mode ignores the updated information
if the pass-through device is setup to use vAPIC regardless of guest_mode.
This could cause invalid interrupt remapping.

Also, the guest_mode bit should be set and cleared only when
SVM updates posted-interrupt interrupt remapping information.

Signed-off-by: Suravee Suthikulpanit <[email protected]>
Cc: Joerg Roedel <[email protected]>
Fixes: d98de49 ('iommu/amd: Enable vAPIC interrupt remapping mode by default')
Signed-off-by: Joerg Roedel <[email protected]>

drivers/iommu/amd_iommu.c

@@ -3879,11 +3879,9 @@ static void irte_ga_prepare(void *entry,
 			    u8 vector, u32 dest_apicid, int devid)
 {
 	struct irte_ga *irte = (struct irte_ga *) entry;
-	struct iommu_dev_data *dev_data = search_dev_data(devid);
 
 	irte->lo.val                      = 0;
 	irte->hi.val                      = 0;
-	irte->lo.fields_remap.guest_mode  = dev_data ? dev_data->use_vapic : 0;
 	irte->lo.fields_remap.int_type    = delivery_mode;
 	irte->lo.fields_remap.dm          = dest_mode;
 	irte->hi.fields.vector            = vector;
@@ -3939,10 +3937,10 @@ static void irte_ga_set_affinity(void *entry, u16 devid, u16 index,
 	struct irte_ga *irte = (struct irte_ga *) entry;
 	struct iommu_dev_data *dev_data = search_dev_data(devid);
 
-	if (!dev_data || !dev_data->use_vapic) {
+	if (!dev_data || !dev_data->use_vapic ||
+	    !irte->lo.fields_remap.guest_mode) {
 		irte->hi.fields.vector = vector;
 		irte->lo.fields_remap.destination = dest_apicid;
-		irte->lo.fields_remap.guest_mode = 0;
 		modify_irte_ga(devid, index, irte, NULL);
 	}
 }