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    Subject[PATCH v3 06/16] iommu/vt-d: Add custom allocator for IOASID
    Date
    When VT-d driver runs in the guest, PASID allocation must be
    performed via virtual command interface. This patch registers a
    custom IOASID allocator which takes precedence over the default
    XArray based allocator. The resulting IOASID allocation will always
    come from the host. This ensures that PASID namespace is system-
    wide.

    Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
    Signed-off-by: Liu, Yi L <yi.l.liu@intel.com>
    Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
    ---
    drivers/iommu/Kconfig | 1 +
    drivers/iommu/intel-iommu.c | 60 +++++++++++++++++++++++++++++++++++++++++++++
    include/linux/intel-iommu.h | 2 ++
    3 files changed, 63 insertions(+)

    diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
    index 75e7f97..d565ef7 100644
    --- a/drivers/iommu/Kconfig
    +++ b/drivers/iommu/Kconfig
    @@ -210,6 +210,7 @@ config INTEL_IOMMU_SVM
    bool "Support for Shared Virtual Memory with Intel IOMMU"
    depends on INTEL_IOMMU && X86
    select PCI_PASID
    + select IOASID
    select MMU_NOTIFIER
    help
    Shared Virtual Memory (SVM) provides a facility for devices
    diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
    index d93c4bd..fcc694a 100644
    --- a/drivers/iommu/intel-iommu.c
    +++ b/drivers/iommu/intel-iommu.c
    @@ -1711,6 +1711,8 @@ static void free_dmar_iommu(struct intel_iommu *iommu)
    if (ecap_prs(iommu->ecap))
    intel_svm_finish_prq(iommu);
    }
    + ioasid_unregister_allocator(&iommu->pasid_allocator);
    +
    #endif
    }

    @@ -4811,6 +4813,46 @@ static int __init platform_optin_force_iommu(void)
    return 1;
    }

    +#ifdef CONFIG_INTEL_IOMMU_SVM
    +static ioasid_t intel_ioasid_alloc(ioasid_t min, ioasid_t max, void *data)
    +{
    + struct intel_iommu *iommu = data;
    + ioasid_t ioasid;
    +
    + /*
    + * VT-d virtual command interface always uses the full 20 bit
    + * PASID range. Host can partition guest PASID range based on
    + * policies but it is out of guest's control.
    + */
    + if (min < PASID_MIN || max > PASID_MAX)
    + return -EINVAL;
    +
    + if (vcmd_alloc_pasid(iommu, &ioasid))
    + return INVALID_IOASID;
    +
    + return ioasid;
    +}
    +
    +static void intel_ioasid_free(ioasid_t ioasid, void *data)
    +{
    + struct iommu_pasid_alloc_info *svm;
    + struct intel_iommu *iommu = data;
    +
    + if (!iommu)
    + return;
    + /*
    + * Sanity check the ioasid owner is done at upper layer, e.g. VFIO
    + * We can only free the PASID when all the devices are unbond.
    + */
    + svm = ioasid_find(NULL, ioasid, NULL);
    + if (!svm) {
    + pr_warn("Freeing unbond IOASID %d\n", ioasid);
    + return;
    + }
    + vcmd_free_pasid(iommu, ioasid);
    +}
    +#endif
    +
    int __init intel_iommu_init(void)
    {
    int ret = -ENODEV;
    @@ -4912,6 +4954,24 @@ int __init intel_iommu_init(void)
    "%s", iommu->name);
    iommu_device_set_ops(&iommu->iommu, &intel_iommu_ops);
    iommu_device_register(&iommu->iommu);
    +#ifdef CONFIG_INTEL_IOMMU_SVM
    + if (cap_caching_mode(iommu->cap) && sm_supported(iommu)) {
    + /*
    + * Register a custom ASID allocator if we are running
    + * in a guest, the purpose is to have a system wide PASID
    + * namespace among all PASID users.
    + * There can be multiple vIOMMUs in each guest but only
    + * one allocator is active. All vIOMMU allocators will
    + * eventually be calling the same host allocator.
    + */
    + iommu->pasid_allocator.alloc = intel_ioasid_alloc;
    + iommu->pasid_allocator.free = intel_ioasid_free;
    + iommu->pasid_allocator.pdata = (void *)iommu;
    + ret = ioasid_register_allocator(&iommu->pasid_allocator);
    + if (ret)
    + pr_warn("Custom PASID allocator registeration failed\n");
    + }
    +#endif
    }

    bus_set_iommu(&pci_bus_type, &intel_iommu_ops);
    diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
    index bff907b..c24c8aa 100644
    --- a/include/linux/intel-iommu.h
    +++ b/include/linux/intel-iommu.h
    @@ -31,6 +31,7 @@
    #include <linux/iommu.h>
    #include <linux/io-64-nonatomic-lo-hi.h>
    #include <linux/dmar.h>
    +#include <linux/ioasid.h>

    #include <asm/cacheflush.h>
    #include <asm/iommu.h>
    @@ -549,6 +550,7 @@ struct intel_iommu {
    #ifdef CONFIG_INTEL_IOMMU_SVM
    struct page_req_dsc *prq;
    unsigned char prq_name[16]; /* Name for PRQ interrupt */
    + struct ioasid_allocator pasid_allocator; /* Custom allocator for PASIDs */
    #endif
    struct q_inval *qi; /* Queued invalidation info */
    u32 *iommu_state; /* Store iommu states between suspend and resume.*/
    --
    2.7.4
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