intel-iommu: Clean up handling of "caching mode" vs. context flushing.

It really doesn't make a lot of sense to have some of the logic to
handle caching vs. non-caching mode duplicated in qi_flush_context() and
__iommu_flush_context(), while the return value indicates whether the
caller should take other action which depends on the same thing.

Especially since qi_flush_context() thought it was returning something
entirely different anyway.

This patch makes qi_flush_context() and __iommu_flush_context() both
return void, removes the 'non_present_entry_flush' argument and makes
the only call site which _set_ that argument to 1 do the right thing.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

2 files changed, 24 insertions, 41 deletions

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index d3d86b749eee..10a071ba3232 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -723,23 +723,16 @@ void qi_global_iec(struct intel_iommu *iommu)
         qi_submit_sync(&desc, iommu);
 }
 
-int qi_flush_context(struct intel_iommu *iommu, u16 did, u16 sid, u8 fm,
-                     u64 type, int non_present_entry_flush)
+void qi_flush_context(struct intel_iommu *iommu, u16 did, u16 sid, u8 fm,
+                      u64 type)
 {
         struct qi_desc desc;
 
-        if (non_present_entry_flush) {
-                if (!cap_caching_mode(iommu->cap))
-                        return 1;
-                else
-                        did = 0;
-        }
-
         desc.low = QI_CC_FM(fm) | QI_CC_SID(sid) | QI_CC_DID(did)
                         | QI_CC_GRAN(type) | QI_CC_TYPE;
         desc.high = 0;
 
-        return qi_submit_sync(&desc, iommu);
+        qi_submit_sync(&desc, iommu);
 }
 
 int qi_flush_iotlb(struct intel_iommu *iommu, u16 did, u64 addr,
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index d6f4ee50924c..9f5d9151edc9 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -857,26 +857,13 @@ static void iommu_flush_write_buffer(struct intel_iommu *iommu)
 }
 
 /* return value determine if we need a write buffer flush */
-static int __iommu_flush_context(struct intel_iommu *iommu,
-        u16 did, u16 source_id, u8 function_mask, u64 type,
-        int non_present_entry_flush)
+static void __iommu_flush_context(struct intel_iommu *iommu,
+                                  u16 did, u16 source_id, u8 function_mask,
+                                  u64 type)
 {
         u64 val = 0;
         unsigned long flag;
 
-        /*
-         * In the non-present entry flush case, if hardware doesn't cache
-         * non-present entry we do nothing and if hardware cache non-present
-         * entry, we flush entries of domain 0 (the domain id is used to cache
-         * any non-present entries)
-         */
-        if (non_present_entry_flush) {
-                if (!cap_caching_mode(iommu->cap))
-                        return 1;
-                else
-                        did = 0;
-        }
-
         switch (type) {
         case DMA_CCMD_GLOBAL_INVL:
                 val = DMA_CCMD_GLOBAL_INVL;
@@ -901,9 +888,6 @@ static int __iommu_flush_context(struct intel_iommu *iommu,
                 dmar_readq, (!(val & DMA_CCMD_ICC)), val);
 
         spin_unlock_irqrestore(&iommu->register_lock, flag);
-
-        /* flush context entry will implicitly flush write buffer */
-        return 0;
 }
 
 /* return value determine if we need a write buffer flush */
@@ -1428,14 +1412,21 @@ static int domain_context_mapping_one(struct dmar_domain *domain, int segment,
         context_set_present(context);
         domain_flush_cache(domain, context, sizeof(*context));
 
-        /* it's a non-present to present mapping */
-        if (iommu->flush.flush_context(iommu, id,
-                (((u16)bus) << 8) | devfn, DMA_CCMD_MASK_NOBIT,
-                DMA_CCMD_DEVICE_INVL, 1))
-                iommu_flush_write_buffer(iommu);
-        else
+        /*
+         * It's a non-present to present mapping. If hardware doesn't cache
+         * non-present entry we only need to flush the write-buffer. If the
+         * _does_ cache non-present entries, then it does so in the special
+         * domain #0, which we have to flush:
+         */
+        if (cap_caching_mode(iommu->cap)) {
+                iommu->flush.flush_context(iommu, 0,
+                                           (((u16)bus) << 8) | devfn,
+                                           DMA_CCMD_MASK_NOBIT,
+                                           DMA_CCMD_DEVICE_INVL);
                 iommu->flush.flush_iotlb(iommu, 0, 0, 0, DMA_TLB_DSI_FLUSH, 0);
-
+        } else {
+                iommu_flush_write_buffer(iommu);
+        }
         spin_unlock_irqrestore(&iommu->lock, flags);
 
         spin_lock_irqsave(&domain->iommu_lock, flags);
@@ -1566,7 +1557,7 @@ static void iommu_detach_dev(struct intel_iommu *iommu, u8 bus, u8 devfn)
 
         clear_context_table(iommu, bus, devfn);
         iommu->flush.flush_context(iommu, 0, 0, 0,
-                                           DMA_CCMD_GLOBAL_INVL, 0);
+                                           DMA_CCMD_GLOBAL_INVL);
         iommu->flush.flush_iotlb(iommu, 0, 0, 0,
                                          DMA_TLB_GLOBAL_FLUSH, 0);
 }
@@ -2104,8 +2095,7 @@ static int __init init_dmars(void)
 
                 iommu_set_root_entry(iommu);
 
-                iommu->flush.flush_context(iommu, 0, 0, 0, DMA_CCMD_GLOBAL_INVL,
-                                           0);
+                iommu->flush.flush_context(iommu, 0, 0, 0, DMA_CCMD_GLOBAL_INVL);
                 iommu->flush.flush_iotlb(iommu, 0, 0, 0, DMA_TLB_GLOBAL_FLUSH,
                                          0);
                 iommu_disable_protect_mem_regions(iommu);
@@ -2721,7 +2711,7 @@ static int init_iommu_hw(void)
                 iommu_set_root_entry(iommu);
 
                 iommu->flush.flush_context(iommu, 0, 0, 0,
-                                                DMA_CCMD_GLOBAL_INVL, 0);
+                                                DMA_CCMD_GLOBAL_INVL);
                 iommu->flush.flush_iotlb(iommu, 0, 0, 0,
                                                 DMA_TLB_GLOBAL_FLUSH, 0);
                 iommu_disable_protect_mem_regions(iommu);
@@ -2738,7 +2728,7 @@ static void iommu_flush_all(void)
 
         for_each_active_iommu(iommu, drhd) {
                 iommu->flush.flush_context(iommu, 0, 0, 0,
-                                                DMA_CCMD_GLOBAL_INVL, 0);
+                                                DMA_CCMD_GLOBAL_INVL);
                 iommu->flush.flush_iotlb(iommu, 0, 0, 0,
                                                 DMA_TLB_GLOBAL_FLUSH, 0);
         }