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>

3 files changed, 43 insertions, 16 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);
 }
 
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index b9cc9c2b03fc..2779354321f5 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -330,17 +330,10 @@ static int hw_pass_through = 1;
 /* si_domain contains mulitple devices */
 #define DOMAIN_FLAG_STATIC_IDENTITY     (1 << 1)
 
-/* define the limit of IOMMUs supported in each domain */
-#ifdef  CONFIG_X86
-# define        IOMMU_UNITS_SUPPORTED   MAX_IO_APICS
-#else
-# define        IOMMU_UNITS_SUPPORTED   64
-#endif
-
 struct dmar_domain {
         int     id;                     /* domain id */
         int     nid;                    /* node id */
-        DECLARE_BITMAP(iommu_bmp, IOMMU_UNITS_SUPPORTED);
+        DECLARE_BITMAP(iommu_bmp, DMAR_UNITS_SUPPORTED);
                                         /* bitmap of iommus this domain uses*/
 
         struct list_head devices;       /* all devices' list */
@@ -2730,12 +2723,12 @@ static int __init init_dmars(void)
                  * threaded kernel __init code path all other access are read
                  * only
                  */
-                if (g_num_of_iommus < IOMMU_UNITS_SUPPORTED) {
+                if (g_num_of_iommus < DMAR_UNITS_SUPPORTED) {
                         g_num_of_iommus++;
                         continue;
                 }
                 printk_once(KERN_ERR "intel-iommu: exceeded %d IOMMUs\n",
-                          IOMMU_UNITS_SUPPORTED);
+                          DMAR_UNITS_SUPPORTED);
         }
 
         g_iommus = kcalloc(g_num_of_iommus, sizeof(struct intel_iommu *),
diff --git a/include/linux/dmar.h b/include/linux/dmar.h
index 495df5e48f80..725204fc433e 100644
--- a/include/linux/dmar.h
+++ b/include/linux/dmar.h
@@ -30,6 +30,12 @@
 
 struct acpi_dmar_header;
 
+#ifdef  CONFIG_X86
+# define        DMAR_UNITS_SUPPORTED    MAX_IO_APICS
+#else
+# define        DMAR_UNITS_SUPPORTED    64
+#endif
+
 /* DMAR Flags */
 #define DMAR_INTR_REMAP         0x1
 #define DMAR_X2APIC_OPT_OUT     0x2