[PATCH 10/18] iommu/vt-d: Add custom allocator for IOASID

[Jacob Pan]

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@xxxxxxxxxxxxxxx>
Signed-off-by: Liu, Yi L <yi.l.liu@xxxxxxxxx>
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
 drivers/iommu/intel-iommu.c | 50 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/intel-iommu.h |  1 +
 2 files changed, 51 insertions(+)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 28cb713..a38d774 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4820,6 +4820,42 @@ 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;
+
+	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;
+}
+
+static struct ioasid_allocator intel_iommu_ioasid_allocator = {
+	.alloc = intel_ioasid_alloc,
+	.free = intel_ioasid_free,
+};
+
 int __init intel_iommu_init(void)
 {
 	int ret = -ENODEV;
@@ -4921,6 +4957,20 @@ 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.
+			 * Note that only one vIOMMU in each guest is supported.
+			 */
+			intel_iommu_ioasid_allocator.pdata = (void *)iommu;
+			ret = ioasid_set_allocator(&intel_iommu_ioasid_allocator);
+			if (ret == -EBUSY) {
+				pr_info("Custom IOASID allocator already registered\n");
+				break;
+			}
+		}
 	}
 
 	bus_set_iommu(&pci_bus_type, &intel_iommu_ops);
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index b29c85c..bc09d80 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>
-- 
2.7.4