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    Subject[PATCH 4.19 457/639] iommu/amd: Make iommu_disable safer
    Date
    From: Kevin Mitchell <kevmitch@arista.com>

    [ Upstream commit 3ddbe913e55516d3e2165d43d4d5570761769878 ]

    Make it safe to call iommu_disable during early init error conditions
    before mmio_base is set, but after the struct amd_iommu has been added
    to the amd_iommu_list. For example, this happens if firmware fails to
    fill in mmio_phys in the ACPI table leading to a NULL pointer
    dereference in iommu_feature_disable.

    Fixes: 2c0ae1720c09c ('iommu/amd: Convert iommu initialization to state machine')
    Signed-off-by: Kevin Mitchell <kevmitch@arista.com>
    Signed-off-by: Joerg Roedel <jroedel@suse.de>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/iommu/amd_iommu_init.c | 3 +++
    1 file changed, 3 insertions(+)

    diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
    index 1e9a5da562f0d..465f28a7844c2 100644
    --- a/drivers/iommu/amd_iommu_init.c
    +++ b/drivers/iommu/amd_iommu_init.c
    @@ -422,6 +422,9 @@ static void iommu_enable(struct amd_iommu *iommu)

    static void iommu_disable(struct amd_iommu *iommu)
    {
    + if (!iommu->mmio_base)
    + return;
    +
    /* Disable command buffer */
    iommu_feature_disable(iommu, CONTROL_CMDBUF_EN);

    --
    2.20.1


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