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>

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index f3f6865..be999ff 100644 (file)
--- 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 d2e3cbf..3ad8940 100644 (file)
--- 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