iommu/vt-d: Dynamically allocate and free seq_id for DMAR units

Introduce functions to support dynamic IOMMU seq_id allocating and
releasing, which will be used to support DMAR hotplug.

Also rename IOMMU_UNITS_SUPPORTED as DMAR_UNITS_SUPPORTED.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Reviewed-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 34 insertions, 6 deletions

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 586dd2aa2ca2..78aa1b2af113 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -70,6 +70,7 @@ LIST_HEAD(dmar_drhd_units);
 struct acpi_table_header * __initdata dmar_tbl;
 static acpi_size dmar_tbl_size;
 static int dmar_dev_scope_status = 1;
+static unsigned long dmar_seq_ids[BITS_TO_LONGS(DMAR_UNITS_SUPPORTED)];
 
 static int alloc_iommu(struct dmar_drhd_unit *drhd);
 static void free_iommu(struct intel_iommu *iommu);
@@ -944,11 +945,32 @@ out:
         return err;
 }
 
+static int dmar_alloc_seq_id(struct intel_iommu *iommu)
+{
+        iommu->seq_id = find_first_zero_bit(dmar_seq_ids,
+                                            DMAR_UNITS_SUPPORTED);
+        if (iommu->seq_id >= DMAR_UNITS_SUPPORTED) {
+                iommu->seq_id = -1;
+        } else {
+                set_bit(iommu->seq_id, dmar_seq_ids);
+                sprintf(iommu->name, "dmar%d", iommu->seq_id);
+        }
+
+        return iommu->seq_id;
+}
+
+static void dmar_free_seq_id(struct intel_iommu *iommu)
+{
+        if (iommu->seq_id >= 0) {
+                clear_bit(iommu->seq_id, dmar_seq_ids);
+                iommu->seq_id = -1;
+        }
+}
+
 static int alloc_iommu(struct dmar_drhd_unit *drhd)
 {
         struct intel_iommu *iommu;
         u32 ver, sts;
-        static int iommu_allocated = 0;
         int agaw = 0;
         int msagaw = 0;
         int err;
@@ -962,13 +984,16 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
         if (!iommu)
                 return -ENOMEM;
 
-        iommu->seq_id = iommu_allocated++;
-        sprintf (iommu->name, "dmar%d", iommu->seq_id);
+        if (dmar_alloc_seq_id(iommu) < 0) {
+                pr_err("IOMMU: failed to allocate seq_id\n");
+                err = -ENOSPC;
+                goto error;
+        }
 
         err = map_iommu(iommu, drhd->reg_base_addr);
         if (err) {
                 pr_err("IOMMU: failed to map %s\n", iommu->name);
-                goto error;
+                goto error_free_seq_id;
         }
 
         err = -EINVAL;
@@ -1018,9 +1043,11 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
 
         return 0;
 
- err_unmap:
+err_unmap:
         unmap_iommu(iommu);
- error:
+error_free_seq_id:
+        dmar_free_seq_id(iommu);
+error:
         kfree(iommu);
         return err;
 }
@@ -1044,6 +1071,7 @@ static void free_iommu(struct intel_iommu *iommu)
         if (iommu->reg)
                 unmap_iommu(iommu);
 
+        dmar_free_seq_id(iommu);
         kfree(iommu);
 }