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


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