linux-kernel - [PATCH] iommu/amd: fix interrupt remapping for avic

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Date:   Sun, 13 Sep 2020 15:42:11 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        iommu@...ts.linux-foundation.org (open list:AMD IOMMU (AMD-VI)),
        Joao Martins <joao.m.martins@...cle.com>,
        Joerg Roedel <joro@...tes.org>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH] iommu/amd: fix interrupt remapping for avic

Commit e52d58d54a32 ("iommu/amd: Use cmpxchg_double() when updating 128-bit IRTE")
accidentally removed an assumption that modify_irte_ga always set the valid bit
and amd_iommu_activate_guest_mode relied on that.

Side effect of this is that on my machine, VFIO based VMs with AVIC enabled
would eventually crash and show IOMMU errors like that:

AMD-Vi: Event logged [IO_PAGE_FAULT domain=0x0055 address=0xfffffffdf8000000 flags=0x0008]

Fixes: e52d58d54a321 ("iommu/amd: Use cmpxchg_double() when updating 128-bit IRTE")
Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 drivers/iommu/amd/iommu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 07ae8b93887e5..aff4cc1869356 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3853,6 +3853,7 @@ int amd_iommu_activate_guest_mode(void *data)
 	entry->hi.fields.ga_root_ptr       = ir_data->ga_root_ptr;
 	entry->hi.fields.vector            = ir_data->ga_vector;
 	entry->lo.fields_vapic.ga_tag      = ir_data->ga_tag;
+	entry->lo.fields_remap.valid = 1;
 
 	return modify_irte_ga(ir_data->irq_2_irte.devid,
 			      ir_data->irq_2_irte.index, entry, ir_data);
-- 
2.26.2