linux-kernel - [PATCH v2] iommu/amd: Fix interrupt remapping when disable guest

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Date:   Mon, 26 Jun 2017 04:28:04 -0500
From:   Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Cc:     joro@...tes.org,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        Joerg Roedel <jroedel@...e.de>
Subject: [PATCH v2] 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 <suravee.suthikulpanit@....com>
Cc: Joerg Roedel <jroedel@...e.de>
---
Changes in v2:
  * Fix compiler warning of unused variable 'dev_data' in
    irte_ga_prepare().

 drivers/iommu/amd_iommu.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index b17536d6..3f25d88 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/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);
 	}
 }
-- 
1.8.3.1