[RFC][PATCH 1/4][intel_iommu] explicit export current graphics dmar status

[Zhenyu Wang]

[PATCH] [intel_iommu] explicit export current graphics dmar status

To make it possbile to tell other modules about curent
graphics dmar engine status, that could decide if graphics
driver should remap physical address to dma address.

Also this one trys to make dmar_disabled really present
current status of DMAR, which would be used for completely
express graphics dmar engine is active or not.

Signed-off-by: Zhenyu Wang <zhenyu.z.wang@xxxxxxxxx>
---
 drivers/pci/intel-iommu.c |   18 ++++++++++++++++--
 include/linux/dmar.h      |    6 ++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index e079a52..81a0abc 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -53,7 +53,7 @@
 static void domain_remove_dev_info(struct dmar_domain *domain);
 
 static int dmar_disabled;
-static int __initdata dmar_map_gfx = 1;
+static int dmar_map_gfx = 1;
 static int dmar_forcedac;
 
 #define DUMMY_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-1))
@@ -86,6 +86,16 @@ static int __init intel_iommu_setup(char *str)
 }
 __setup("intel_iommu=", intel_iommu_setup);
 
+int intel_iommu_gfx_remapping(void)
+{
+#ifndef CONFIG_DMAR_GFX_WA
+	if (!dmar_disabled && iommu_detected && dmar_map_gfx)
+		return 1;
+#endif
+	return 0;
+}
+EXPORT_SYMBOL_GPL(intel_iommu_gfx_remapping);
+
 static struct kmem_cache *iommu_domain_cache;
 static struct kmem_cache *iommu_devinfo_cache;
 static struct kmem_cache *iommu_iova_cache;
@@ -2189,8 +2199,12 @@ static void __init iommu_exit_mempool(void)
 
 void __init detect_intel_iommu(void)
 {
-	if (swiotlb || no_iommu || iommu_detected || dmar_disabled)
+	if (dmar_disabled)
+		return;
+	if (swiotlb || no_iommu || iommu_detected) {
+		dmar_disabled = 1;
 		return;
+	}
 	if (early_dmar_detect()) {
 		iommu_detected = 1;
 	}
diff --git a/include/linux/dmar.h b/include/linux/dmar.h
index ffb6439..8ae435e 100644
--- a/include/linux/dmar.h
+++ b/include/linux/dmar.h
@@ -47,6 +47,8 @@ extern int intel_iommu_init(void);
 extern int dmar_table_init(void);
 extern int early_dmar_detect(void);
 
+extern int intel_iommu_gfx_remapping(void);
+
 extern struct list_head dmar_drhd_units;
 extern struct list_head dmar_rmrr_units;
 
@@ -81,6 +83,10 @@ static inline int intel_iommu_init(void)
 {
 	return -ENODEV;
 }
+static inline int intel_iommu_gfx_remapping(void)
+{
+	return 0;
+}
 
 #endif /* !CONFIG_DMAR */
 #endif /* __DMAR_H__ */
-- 
1.5.3.5

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