[PATCH v2 10/19] iommu/vt-d: Add custom allocator for IOASID

Jacob Pan
2019-04-23T23:29:43Z

When VT-d driver runs in the guest, PASID allocation must be
performed via virtual command interface. This patch register a
custom IOASID allocator which takes precedence over the default
IDR 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/intel-iommu.c | 58 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/intel-iommu.h | 2 ++
2 files changed, 60 insertions(+)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index d93c4bd..ec6f22d 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;
}

+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 int intel_ioasid_free(ioasid_t ioasid, void *data)
+{
+ struct iommu_pasid_alloc_info *svm;
+ struct intel_iommu *iommu = data;
+
+ if (!iommu || !cap_caching_mode(iommu->cap))
+ return -EINVAL;
+ /*
+ * 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 -EBUSY;
+ }
+ vcmd_free_pasid(iommu, ioasid);
+
+ return 0;
+}
+
int __init intel_iommu_init(void)
{
int ret = -ENODEV;
@@ -4912,6 +4954,22 @@ int __init intel_iommu_init(void)
"%s", iommu->name);
iommu_device_set_ops(&iommu->iommu, &intel_iommu_ops);
iommu_device_register(&iommu->iommu);
+ 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");
+ }
}

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