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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Maxim Levitsky <mlevitsk@redhat.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
        Joao Martins <joao.m.martins@oracle.com>,
        Joerg Roedel <jroedel@suse.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.8 074/118] iommu/amd: Restore IRTE.RemapEn bit for amd_iommu_activate_guest_mode
Date:   Mon, 21 Sep 2020 18:28:06 +0200
Message-Id: <20200921162039.772722555@linuxfoundation.org>
In-Reply-To: <20200921162036.324813383@linuxfoundation.org>
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From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

[ 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
amd_iommu_deactivate_guest_mode().

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@redhat.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Tested-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Link: https://lore.kernel.org/r/20200916111720.43913-1-suravee.suthikulpanit@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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;
-- 
2.25.1