iommu/amd: Restore IRTE.RemapEn bit for amd_iommu_activate_guest_mode

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>

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 8abe1c7ad45be5c98cce1f35668c6ac40638e6d1..10e4200d355204d51ac988477874b3c2be2976c3 100644 (file)
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3840,14 +3840,18 @@ 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;