intel-iommu: Snooping control support

Snooping control enabled IOMMU to guarantee DMA cache coherency and thus reduce
software effort (VMM) in maintaining effective memory type.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

2 files changed, 34 insertions, 6 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index f3f686581a9..be999ff025a 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -231,6 +231,7 @@ struct dmar_domain {
         int             flags;          /* flags to find out type of domain */
 
         int             iommu_coherency;/* indicate coherency of iommu access */
+        int             iommu_snooping; /* indicate snooping control feature*/
         int             iommu_count;    /* reference count of iommu */
         spinlock_t      iommu_lock;     /* protect iommu set in domain */
         u64             max_addr;       /* maximum mapped address */
@@ -421,7 +422,6 @@ static struct intel_iommu *domain_get_iommu(struct dmar_domain *domain)
         return g_iommus[iommu_id];
 }
 
-/* "Coherency" capability may be different across iommus */
 static void domain_update_iommu_coherency(struct dmar_domain *domain)
 {
         int i;
@@ -438,6 +438,29 @@ static void domain_update_iommu_coherency(struct dmar_domain *domain)
         }
 }
 
+static void domain_update_iommu_snooping(struct dmar_domain *domain)
+{
+        int i;
+
+        domain->iommu_snooping = 1;
+
+        i = find_first_bit(&domain->iommu_bmp, g_num_of_iommus);
+        for (; i < g_num_of_iommus; ) {
+                if (!ecap_sc_support(g_iommus[i]->ecap)) {
+                        domain->iommu_snooping = 0;
+                        break;
+                }
+                i = find_next_bit(&domain->iommu_bmp, g_num_of_iommus, i+1);
+        }
+}
+
+/* Some capabilities may be different across iommus */
+static void domain_update_iommu_cap(struct dmar_domain *domain)
+{
+        domain_update_iommu_coherency(domain);
+        domain_update_iommu_snooping(domain);
+}
+
 static struct intel_iommu *device_to_iommu(u8 bus, u8 devfn)
 {
         struct dmar_drhd_unit *drhd = NULL;
@@ -1429,6 +1452,11 @@ static int domain_init(struct dmar_domain *domain, int guest_width)
         else
                 domain->iommu_coherency = 0;
 
+        if (ecap_sc_support(iommu->ecap))
+                domain->iommu_snooping = 1;
+        else
+                domain->iommu_snooping = 0;
+
         domain->iommu_count = 1;
 
         /* always allocate the top pgd */
@@ -1557,7 +1585,7 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
         spin_lock_irqsave(&domain->iommu_lock, flags);
         if (!test_and_set_bit(iommu->seq_id, &domain->iommu_bmp)) {
                 domain->iommu_count++;
-                domain_update_iommu_coherency(domain);
+                domain_update_iommu_cap(domain);
         }
         spin_unlock_irqrestore(&domain->iommu_lock, flags);
         return 0;
@@ -2820,7 +2848,7 @@ static void vm_domain_remove_one_dev_info(struct dmar_domain *domain,
                 spin_lock_irqsave(&domain->iommu_lock, tmp_flags);
                 clear_bit(iommu->seq_id, &domain->iommu_bmp);
                 domain->iommu_count--;
-                domain_update_iommu_coherency(domain);
+                domain_update_iommu_cap(domain);
                 spin_unlock_irqrestore(&domain->iommu_lock, tmp_flags);
         }
 
@@ -2848,13 +2876,13 @@ static void vm_domain_remove_all_dev_info(struct dmar_domain *domain)
                 iommu_detach_dev(iommu, info->bus, info->devfn);
 
                 /* clear this iommu in iommu_bmp, update iommu count
-                 * and coherency
+                 * and capabilities
                  */
                 spin_lock_irqsave(&domain->iommu_lock, flags2);
                 if (test_and_clear_bit(iommu->seq_id,
                                        &domain->iommu_bmp)) {
                         domain->iommu_count--;
-                        domain_update_iommu_coherency(domain);
+                        domain_update_iommu_cap(domain);
                 }
                 spin_unlock_irqrestore(&domain->iommu_lock, flags2);
 
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index d2e3cbfba14..3ad89400493 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -123,7 +123,7 @@ static inline void dmar_writeq(void __iomem *addr, u64 val)
 #define ecap_eim_support(e)     ((e >> 4) & 0x1)
 #define ecap_ir_support(e)      ((e >> 3) & 0x1)
 #define ecap_max_handle_mask(e) ((e >> 20) & 0xf)
-
+#define ecap_sc_support(e)      ((e >> 7) & 0x1) /* Snooping Control */
 
 /* IOTLB_REG */
 #define DMA_TLB_FLUSH_GRANU_OFFSET  60