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    Subject[PATCH 5.15 198/779] ACPI: VIOT: Fix ACS setup
    Date
    From: Eric Auger <eric.auger@redhat.com>

    [ Upstream commit 3dcb861dbc6ab101838a1548b1efddd00ca3c3ec ]

    Currently acpi_viot_init() gets called after the pci
    device has been scanned and pci_enable_acs() has been called.
    So pci_request_acs() fails to be taken into account leading
    to wrong single iommu group topologies when dealing with
    multi-function root ports for instance.

    We cannot simply move the acpi_viot_init() earlier, similarly
    as the IORT init because the VIOT parsing relies on the pci
    scan. However we can detect VIOT is present earlier and in
    such a case, request ACS. Introduce a new acpi_viot_early_init()
    routine that allows to call pci_request_acs() before the scan.

    While at it, guard the call to pci_request_acs() with #ifdef
    CONFIG_PCI.

    Fixes: 3cf485540e7b ("ACPI: Add driver for the VIOT table")
    Signed-off-by: Eric Auger <eric.auger@redhat.com>
    Reported-by: Jin Liu <jinl@redhat.com>
    Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
    Tested-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/acpi/bus.c | 1 +
    drivers/acpi/viot.c | 26 ++++++++++++++++++++------
    include/linux/acpi_viot.h | 2 ++
    3 files changed, 23 insertions(+), 6 deletions(-)

    diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
    index fc9bb06d5411..7774b603a796 100644
    --- a/drivers/acpi/bus.c
    +++ b/drivers/acpi/bus.c
    @@ -1340,6 +1340,7 @@ static int __init acpi_init(void)

    pci_mmcfg_late_init();
    acpi_iort_init();
    + acpi_viot_early_init();
    acpi_hest_init();
    ghes_init();
    acpi_scan_init();
    diff --git a/drivers/acpi/viot.c b/drivers/acpi/viot.c
    index d2256326c73a..647f11cf165d 100644
    --- a/drivers/acpi/viot.c
    +++ b/drivers/acpi/viot.c
    @@ -248,6 +248,26 @@ static int __init viot_parse_node(const struct acpi_viot_header *hdr)
    return ret;
    }

    +/**
    + * acpi_viot_early_init - Test the presence of VIOT and enable ACS
    + *
    + * If the VIOT does exist, ACS must be enabled. This cannot be
    + * done in acpi_viot_init() which is called after the bus scan
    + */
    +void __init acpi_viot_early_init(void)
    +{
    +#ifdef CONFIG_PCI
    + acpi_status status;
    + struct acpi_table_header *hdr;
    +
    + status = acpi_get_table(ACPI_SIG_VIOT, 0, &hdr);
    + if (ACPI_FAILURE(status))
    + return;
    + pci_request_acs();
    + acpi_put_table(hdr);
    +#endif
    +}
    +
    /**
    * acpi_viot_init - Parse the VIOT table
    *
    @@ -319,12 +339,6 @@ static int viot_pci_dev_iommu_init(struct pci_dev *pdev, u16 dev_id, void *data)
    epid = ((domain_nr - ep->segment_start) << 16) +
    dev_id - ep->bdf_start + ep->endpoint_id;

    - /*
    - * If we found a PCI range managed by the viommu, we're
    - * the one that has to request ACS.
    - */
    - pci_request_acs();
    -
    return viot_dev_iommu_init(&pdev->dev, ep->viommu,
    epid);
    }
    diff --git a/include/linux/acpi_viot.h b/include/linux/acpi_viot.h
    index 1eb8ee5b0e5f..a5a122431563 100644
    --- a/include/linux/acpi_viot.h
    +++ b/include/linux/acpi_viot.h
    @@ -6,9 +6,11 @@
    #include <linux/acpi.h>

    #ifdef CONFIG_ACPI_VIOT
    +void __init acpi_viot_early_init(void);
    void __init acpi_viot_init(void);
    int viot_iommu_configure(struct device *dev);
    #else
    +static inline void acpi_viot_early_init(void) {}
    static inline void acpi_viot_init(void) {}
    static inline int viot_iommu_configure(struct device *dev)
    {
    --
    2.35.1


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