iommu/vt-d: Removed unused iommu_count in dmar domain

DMAR domain uses per DMAR refcount. It is indexed by iommu seq_id.
Older iommu_count is only incremented and decremented but no decisions
are taken based on this refcount. This is not of much use.

Hence, remove iommu_count and further simplify domain_detach_iommu()
by returning void.

Signed-off-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210530075053.264218-1-parav@nvidia.com
Link: https://lore.kernel.org/r/20210610020115.1637656-21-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 430ef22..dd8ecfb 100644 (file)
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1920,7 +1920,6 @@ static int domain_attach_iommu(struct dmar_domain *domain,
        assert_spin_locked(&iommu->lock);
 
        domain->iommu_refcnt[iommu->seq_id] += 1;
-       domain->iommu_count += 1;
        if (domain->iommu_refcnt[iommu->seq_id] == 1) {
                ndomains = cap_ndoms(iommu->cap);
                num      = find_first_zero_bit(iommu->domain_ids, ndomains);
@@ -1928,7 +1927,6 @@ static int domain_attach_iommu(struct dmar_domain *domain,
                if (num >= ndomains) {
                        pr_err("%s: No free domain ids\n", iommu->name);
                        domain->iommu_refcnt[iommu->seq_id] -= 1;
-                       domain->iommu_count -= 1;
                        return -ENOSPC;
                }
 
@@ -1944,16 +1942,15 @@ static int domain_attach_iommu(struct dmar_domain *domain,
        return 0;
 }
 
-static int domain_detach_iommu(struct dmar_domain *domain,
-                              struct intel_iommu *iommu)
+static void domain_detach_iommu(struct dmar_domain *domain,
+                               struct intel_iommu *iommu)
 {
-       int num, count;
+       int num;
 
        assert_spin_locked(&device_domain_lock);
        assert_spin_locked(&iommu->lock);
 
        domain->iommu_refcnt[iommu->seq_id] -= 1;
-       count = --domain->iommu_count;
        if (domain->iommu_refcnt[iommu->seq_id] == 0) {
                num = domain->iommu_did[iommu->seq_id];
                clear_bit(num, iommu->domain_ids);
@@ -1962,8 +1959,6 @@ static int domain_detach_iommu(struct dmar_domain *domain,
                domain_update_iommu_cap(domain);
                domain->iommu_did[iommu->seq_id] = 0;
        }
-
-       return count;
 }
 
 static inline int guestwidth_to_adjustwidth(int gaw)

diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 2621eff..574b932 100644 (file)
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -561,7 +561,6 @@ struct dmar_domain {
        int             agaw;
 
        int             flags;          /* flags to find out type of domain */
-       int             iommu_count;    /* reference count of iommu */
        int             iommu_superpage;/* Level of superpages supported:
                                           0 == 4KiB (no superpages), 1 == 2MiB,
                                           2 == 1GiB, 3 == 512GiB, 4 == 1TiB */