Intel IOMMU: Intel iommu cmdline option - forcedac

Introduce intel_iommu=forcedac commandline option.  This option is helpful to
verify the pci device capability of handling physical dma'able address greater
than 4G.

Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Muli Ben-Yehuda <muli@il.ibm.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 05630b44dbfc..cb24defdb6d9 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -54,6 +54,7 @@ static void domain_remove_dev_info(struct dmar_domain *domain);
 
 static int dmar_disabled;
 static int __initdata dmar_map_gfx = 1;
+static int dmar_forcedac;
 
 #define DUMMY_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-1))
 static DEFINE_SPINLOCK(device_domain_lock);
@@ -71,6 +72,10 @@ static int __init intel_iommu_setup(char *str)
                         dmar_map_gfx = 0;
                         printk(KERN_INFO
                                 "Intel-IOMMU: disable GFX device mapping\n");
+                } else if (!strncmp(str, "forcedac", 8)) {
+                        printk (KERN_INFO
+                                "Intel-IOMMU: Forcing DAC for PCI devices\n");
+                        dmar_forcedac = 1;
                 }
 
                 str += strcspn(str, ",");
@@ -1558,7 +1563,7 @@ static dma_addr_t __intel_map_single(struct device *dev, void *addr,
 
         start_addr = IOVA_START_ADDR;
 
-        if (pdev->dma_mask <= DMA_32BIT_MASK) {
+        if ((pdev->dma_mask <= DMA_32BIT_MASK) || (dmar_forcedac)) {
                 iova = iommu_alloc_iova(domain, addr, size, start_addr,
                         pdev->dma_mask);
         } else  {