[PATCH 5.8 074/118] iommu/amd: Restore IRTE.RemapEn bit for amd_iommu_activate_guest_mode

From: Greg Kroah-Hartman
Date: Mon Sep 21 2020 - 12:55:32 EST

From: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>

[ Upstream commit e97685abd5d711c885053d4949178f7ab9acbaef ]

Commit e52d58d54a32 ("iommu/amd: Use cmpxchg_double() when updating
128-bit IRTE") removed an assumption that modify_irte_ga always set
the valid bit, which requires the callers to set the appropriate value
for the struct irte_ga.valid bit before calling the function.

Similar to the commit 26e495f34107 ("iommu/amd: Restore IRTE.RemapEn
bit after programming IRTE"), which is for the function

The same change is also needed for the amd_iommu_activate_guest_mode().
Otherwise, this could trigger IO_PAGE_FAULT for the VFIO based VMs with
AVIC enabled.

Fixes: e52d58d54a321 ("iommu/amd: Use cmpxchg_double() when updating 128-bit IRTE")
Reported-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
Tested-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Reviewed-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Cc: Joao Martins <joao.m.martins@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20200916111720.43913-1-suravee.suthikulpanit@xxxxxxx
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/iommu/amd/iommu.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 48fe272da6e9c..a51dcf26b09f2 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3831,14 +3831,18 @@ int amd_iommu_activate_guest_mode(void *data)
struct amd_ir_data *ir_data = (struct amd_ir_data *)data;
struct irte_ga *entry = (struct irte_ga *) ir_data->entry;
+ u64 valid;

if (!AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir) ||
!entry || entry->lo.fields_vapic.guest_mode)
return 0;

+ valid = entry->lo.fields_vapic.valid;
entry->lo.val = 0;
entry->hi.val = 0;

+ entry->lo.fields_vapic.valid = valid;
entry->lo.fields_vapic.guest_mode = 1;
entry->lo.fields_vapic.ga_log_intr = 1;
entry->hi.fields.ga_root_ptr = ir_data->ga_root_ptr;