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    Subject[PATCH 4.14 34/92] iommu/vt-d: Check capability before disabling protected memory
    Date
    [ Upstream commit 5bb71fc790a88d063507dc5d445ab8b14e845591 ]

    The spec states in 10.4.16 that the Protected Memory Enable
    Register should be treated as read-only for implementations
    not supporting protected memory regions (PLMR and PHMR fields
    reported as Clear in the Capability register).

    Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
    Cc: mark gross <mgross@intel.com>
    Suggested-by: Ashok Raj <ashok.raj@intel.com>
    Fixes: f8bab73515ca5 ("intel-iommu: PMEN support")
    Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
    Signed-off-by: Joerg Roedel <jroedel@suse.de>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/iommu/intel-iommu.c | 3 +++
    1 file changed, 3 insertions(+)

    diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
    index 802ba7b16e09..fe935293fa7b 100644
    --- a/drivers/iommu/intel-iommu.c
    +++ b/drivers/iommu/intel-iommu.c
    @@ -1646,6 +1646,9 @@ static void iommu_disable_protect_mem_regions(struct intel_iommu *iommu)
    u32 pmen;
    unsigned long flags;

    + if (!cap_plmr(iommu->cap) && !cap_phmr(iommu->cap))
    + return;
    +
    raw_spin_lock_irqsave(&iommu->register_lock, flags);
    pmen = readl(iommu->reg + DMAR_PMEN_REG);
    pmen &= ~DMA_PMEN_EPM;
    --
    2.19.1


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