intel-iommu: IA64 support

The current Intel IOMMU code assumes that both host page size and Intel
IOMMU page size are 4KiB. The first patch supports variable page size.
This provides support for IA64 which has multiple page sizes.

This patch also adds some other code hooks for IA64 platform including
DMAR_OPERATION_TIMEOUT definition.

[dwmw2: some cleanup]
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

3 files changed, 91 insertions, 70 deletions

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 44d6c70..b651738 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -277,14 +277,15 @@ dmar_table_print_dmar_entry(struct acpi_dmar_header *header)
 		drhd = (struct acpi_dmar_hardware_unit *)header;
 		printk (KERN_INFO PREFIX
 			"DRHD (flags: 0x%08x)base: 0x%016Lx\n",
-			drhd->flags, drhd->address);
+			drhd->flags, (unsigned long long)drhd->address);
 		break;
 	case ACPI_DMAR_TYPE_RESERVED_MEMORY:
 		rmrr = (struct acpi_dmar_reserved_memory *)header;
 
 		printk (KERN_INFO PREFIX
 			"RMRR base: 0x%016Lx end: 0x%016Lx\n",
-			rmrr->base_address, rmrr->end_address);
+			(unsigned long long)rmrr->base_address,
+			(unsigned long long)rmrr->end_address);
 		break;
 	}
 }
@@ -304,7 +305,7 @@ parse_dmar_table(void)
 	if (!dmar)
 		return -ENODEV;
 
-	if (dmar->width < PAGE_SHIFT_4K - 1) {
+	if (dmar->width < PAGE_SHIFT - 1) {
 		printk(KERN_WARNING PREFIX "Invalid DMAR haw\n");
 		return -EINVAL;
 	}
@@ -493,7 +494,7 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
 
 	iommu->seq_id = iommu_allocated++;
 
-	iommu->reg = ioremap(drhd->reg_base_addr, PAGE_SIZE_4K);
+	iommu->reg = ioremap(drhd->reg_base_addr, VTD_PAGE_SIZE);
 	if (!iommu->reg) {
 		printk(KERN_ERR "IOMMU: can't map the region\n");
 		goto error;
@@ -504,8 +505,8 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
 	/* the registers might be more than one page */
 	map_size = max_t(int, ecap_max_iotlb_offset(iommu->ecap),
 		cap_max_fault_reg_offset(iommu->cap));
-	map_size = PAGE_ALIGN_4K(map_size);
-	if (map_size > PAGE_SIZE_4K) {
+	map_size = VTD_PAGE_ALIGN(map_size);
+	if (map_size > VTD_PAGE_SIZE) {
 		iounmap(iommu->reg);
 		iommu->reg = ioremap(drhd->reg_base_addr, map_size);
 		if (!iommu->reg) {
@@ -516,8 +517,10 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
 
 	ver = readl(iommu->reg + DMAR_VER_REG);
 	pr_debug("IOMMU %llx: ver %d:%d cap %llx ecap %llx\n",
-		drhd->reg_base_addr, DMAR_VER_MAJOR(ver), DMAR_VER_MINOR(ver),
-		iommu->cap, iommu->ecap);
+		(unsigned long long)drhd->reg_base_addr,
+		DMAR_VER_MAJOR(ver), DMAR_VER_MINOR(ver),
+		(unsigned long long)iommu->cap,
+		(unsigned long long)iommu->ecap);
 
 	spin_lock_init(&iommu->register_lock);
 
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 5094704..2bf96ba 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -18,6 +18,7 @@
  * Author: Ashok Raj <ashok.raj@intel.com>
  * Author: Shaohua Li <shaohua.li@intel.com>
  * Author: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
+ * Author: Fenghua Yu <fenghua.yu@intel.com>
  */
 
 #include <linux/init.h>
@@ -35,11 +36,13 @@
 #include <linux/timer.h>
 #include <linux/iova.h>
 #include <linux/intel-iommu.h>
-#include <asm/proto.h> /* force_iommu in this header in x86-64*/
 #include <asm/cacheflush.h>
 #include <asm/iommu.h>
 #include "pci.h"
 
+#define ROOT_SIZE		VTD_PAGE_SIZE
+#define CONTEXT_SIZE		VTD_PAGE_SIZE
+
 #define IS_GFX_DEVICE(pdev) ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY)
 #define IS_ISA_DEVICE(pdev) ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA)
 
@@ -199,7 +202,7 @@ static struct context_entry * device_to_context_entry(struct intel_iommu *iommu,
 			spin_unlock_irqrestore(&iommu->lock, flags);
 			return NULL;
 		}
-		__iommu_flush_cache(iommu, (void *)context, PAGE_SIZE_4K);
+		__iommu_flush_cache(iommu, (void *)context, CONTEXT_SIZE);
 		phy_addr = virt_to_phys((void *)context);
 		set_root_value(root, phy_addr);
 		set_root_present(root);
@@ -345,7 +348,7 @@ static struct dma_pte * addr_to_dma_pte(struct dmar_domain *domain, u64 addr)
 				return NULL;
 			}
 			__iommu_flush_cache(domain->iommu, tmp_page,
-					PAGE_SIZE_4K);
+					PAGE_SIZE);
 			dma_set_pte_addr(*pte, virt_to_phys(tmp_page));
 			/*
 			 * high level table always sets r/w, last level page
@@ -408,13 +411,13 @@ static void dma_pte_clear_range(struct dmar_domain *domain, u64 start, u64 end)
 	start &= (((u64)1) << addr_width) - 1;
 	end &= (((u64)1) << addr_width) - 1;
 	/* in case it's partial page */
-	start = PAGE_ALIGN_4K(start);
-	end &= PAGE_MASK_4K;
+	start = PAGE_ALIGN(start);
+	end &= PAGE_MASK;
 
 	/* we don't need lock here, nobody else touches the iova range */
 	while (start < end) {
 		dma_pte_clear_one(domain, start);
-		start += PAGE_SIZE_4K;
+		start += VTD_PAGE_SIZE;
 	}
 }
 
@@ -468,7 +471,7 @@ static int iommu_alloc_root_entry(struct intel_iommu *iommu)
 	if (!root)
 		return -ENOMEM;
 
-	__iommu_flush_cache(iommu, root, PAGE_SIZE_4K);
+	__iommu_flush_cache(iommu, root, ROOT_SIZE);
 
 	spin_lock_irqsave(&iommu->lock, flags);
 	iommu->root_entry = root;
@@ -634,7 +637,8 @@ static int __iommu_flush_iotlb(struct intel_iommu *iommu, u16 did,
 		printk(KERN_ERR"IOMMU: flush IOTLB failed\n");
 	if (DMA_TLB_IAIG(val) != DMA_TLB_IIRG(type))
 		pr_debug("IOMMU: tlb flush request %Lx, actual %Lx\n",
-			DMA_TLB_IIRG(type), DMA_TLB_IAIG(val));
+			(unsigned long long)DMA_TLB_IIRG(type),
+			(unsigned long long)DMA_TLB_IAIG(val));
 	/* flush context entry will implictly flush write buffer */
 	return 0;
 }
@@ -644,7 +648,7 @@ static int iommu_flush_iotlb_psi(struct intel_iommu *iommu, u16 did,
 {
 	unsigned int mask;
 
-	BUG_ON(addr & (~PAGE_MASK_4K));
+	BUG_ON(addr & (~VTD_PAGE_MASK));
 	BUG_ON(pages == 0);
 
 	/* Fallback to domain selective flush if no PSI support */
@@ -798,7 +802,7 @@ void dmar_msi_read(int irq, struct msi_msg *msg)
 }
 
 static int iommu_page_fault_do_one(struct intel_iommu *iommu, int type,
-		u8 fault_reason, u16 source_id, u64 addr)
+		u8 fault_reason, u16 source_id, unsigned long long addr)
 {
 	const char *reason;
 
@@ -1051,9 +1055,9 @@ static void dmar_init_reserved_ranges(void)
 			if (!r->flags || !(r->flags & IORESOURCE_MEM))
 				continue;
 			addr = r->start;
-			addr &= PAGE_MASK_4K;
+			addr &= PAGE_MASK;
 			size = r->end - addr;
-			size = PAGE_ALIGN_4K(size);
+			size = PAGE_ALIGN(size);
 			iova = reserve_iova(&reserved_iova_list, IOVA_PFN(addr),
 				IOVA_PFN(size + addr) - 1);
 			if (!iova)
@@ -1115,7 +1119,7 @@ static int domain_init(struct dmar_domain *domain, int guest_width)
 	domain->pgd = (struct dma_pte *)alloc_pgtable_page();
 	if (!domain->pgd)
 		return -ENOMEM;
-	__iommu_flush_cache(iommu, domain->pgd, PAGE_SIZE_4K);
+	__iommu_flush_cache(iommu, domain->pgd, PAGE_SIZE);
 	return 0;
 }
 
@@ -1131,7 +1135,7 @@ static void domain_exit(struct dmar_domain *domain)
 	/* destroy iovas */
 	put_iova_domain(&domain->iovad);
 	end = DOMAIN_MAX_ADDR(domain->gaw);
-	end = end & (~PAGE_MASK_4K);
+	end = end & (~PAGE_MASK);
 
 	/* clear ptes */
 	dma_pte_clear_range(domain, 0, end);
@@ -1252,22 +1256,25 @@ domain_page_mapping(struct dmar_domain *domain, dma_addr_t iova,
 	u64 start_pfn, end_pfn;
 	struct dma_pte *pte;
 	int index;
+	int addr_width = agaw_to_width(domain->agaw);
+
+	hpa &= (((u64)1) << addr_width) - 1;
 
 	if ((prot & (DMA_PTE_READ|DMA_PTE_WRITE)) == 0)
 		return -EINVAL;
-	iova &= PAGE_MASK_4K;
-	start_pfn = ((u64)hpa) >> PAGE_SHIFT_4K;
-	end_pfn = (PAGE_ALIGN_4K(((u64)hpa) + size)) >> PAGE_SHIFT_4K;
+	iova &= PAGE_MASK;
+	start_pfn = ((u64)hpa) >> VTD_PAGE_SHIFT;
+	end_pfn = (VTD_PAGE_ALIGN(((u64)hpa) + size)) >> VTD_PAGE_SHIFT;
 	index = 0;
 	while (start_pfn < end_pfn) {
-		pte = addr_to_dma_pte(domain, iova + PAGE_SIZE_4K * index);
+		pte = addr_to_dma_pte(domain, iova + VTD_PAGE_SIZE * index);
 		if (!pte)
 			return -ENOMEM;
 		/* We don't need lock here, nobody else
 		 * touches the iova range
 		 */
 		BUG_ON(dma_pte_addr(*pte));
-		dma_set_pte_addr(*pte, start_pfn << PAGE_SHIFT_4K);
+		dma_set_pte_addr(*pte, start_pfn << VTD_PAGE_SHIFT);
 		dma_set_pte_prot(*pte, prot);
 		__iommu_flush_cache(domain->iommu, pte, sizeof(*pte));
 		start_pfn++;
@@ -1445,11 +1452,13 @@ error:
 	return find_domain(pdev);
 }
 
-static int iommu_prepare_identity_map(struct pci_dev *pdev, u64 start, u64 end)
+static int iommu_prepare_identity_map(struct pci_dev *pdev,
+				      unsigned long long start,
+				      unsigned long long end)
 {
 	struct dmar_domain *domain;
 	unsigned long size;
-	u64 base;
+	unsigned long long base;
 	int ret;
 
 	printk(KERN_INFO
@@ -1461,9 +1470,9 @@ static int iommu_prepare_identity_map(struct pci_dev *pdev, u64 start, u64 end)
 		return -ENOMEM;
 
 	/* The address might not be aligned */
-	base = start & PAGE_MASK_4K;
+	base = start & PAGE_MASK;
 	size = end - base;
-	size = PAGE_ALIGN_4K(size);
+	size = PAGE_ALIGN(size);
 	if (!reserve_iova(&domain->iovad, IOVA_PFN(base),
 			IOVA_PFN(base + size) - 1)) {
 		printk(KERN_ERR "IOMMU: reserve iova failed\n");
@@ -1732,8 +1741,8 @@ error:
 static inline u64 aligned_size(u64 host_addr, size_t size)
 {
 	u64 addr;
-	addr = (host_addr & (~PAGE_MASK_4K)) + size;
-	return PAGE_ALIGN_4K(addr);
+	addr = (host_addr & (~PAGE_MASK)) + size;
+	return PAGE_ALIGN(addr);
 }
 
 struct iova *
@@ -1747,7 +1756,7 @@ iommu_alloc_iova(struct dmar_domain *domain, size_t size, u64 end)
 		return NULL;
 
 	piova = alloc_iova(&domain->iovad,
-			size >> PAGE_SHIFT_4K, IOVA_PFN(end), 1);
+			size >> PAGE_SHIFT, IOVA_PFN(end), 1);
 	return piova;
 }
 
@@ -1807,12 +1816,12 @@ get_valid_domain_for_dev(struct pci_dev *pdev)
 	return domain;
 }
 
-static dma_addr_t
+dma_addr_t
 intel_map_single(struct device *hwdev, phys_addr_t paddr, size_t size, int dir)
 {
 	struct pci_dev *pdev = to_pci_dev(hwdev);
 	struct dmar_domain *domain;
-	unsigned long start_paddr;
+	phys_addr_t start_paddr;
 	struct iova *iova;
 	int prot = 0;
 	int ret;
@@ -1831,7 +1840,7 @@ intel_map_single(struct device *hwdev, phys_addr_t paddr, size_t size, int dir)
 	if (!iova)
 		goto error;
 
-	start_paddr = iova->pfn_lo << PAGE_SHIFT_4K;
+	start_paddr = (phys_addr_t)iova->pfn_lo << PAGE_SHIFT;
 
 	/*
 	 * Check if DMAR supports zero-length reads on write only
@@ -1849,27 +1858,23 @@ intel_map_single(struct device *hwdev, phys_addr_t paddr, size_t size, int dir)
 	 * is not a big problem
 	 */
 	ret = domain_page_mapping(domain, start_paddr,
-		((u64)paddr) & PAGE_MASK_4K, size, prot);
+		((u64)paddr) & PAGE_MASK, size, prot);
 	if (ret)
 		goto error;
 
-	pr_debug("Device %s request: %lx@%llx mapping: %lx@%llx, dir %d\n",
-		pci_name(pdev), size, (u64)paddr,
-		size, (u64)start_paddr, dir);
-
 	/* it's a non-present to present mapping */
 	ret = iommu_flush_iotlb_psi(domain->iommu, domain->id,
-			start_paddr, size >> PAGE_SHIFT_4K, 1);
+			start_paddr, size >> VTD_PAGE_SHIFT, 1);
 	if (ret)
 		iommu_flush_write_buffer(domain->iommu);
 
-	return (start_paddr + ((u64)paddr & (~PAGE_MASK_4K)));
+	return start_paddr + ((u64)paddr & (~PAGE_MASK));
 
 error:
 	if (iova)
 		__free_iova(&domain->iovad, iova);
 	printk(KERN_ERR"Device %s request: %lx@%llx dir %d --- failed\n",
-		pci_name(pdev), size, (u64)paddr, dir);
+		pci_name(pdev), size, (unsigned long long)paddr, dir);
 	return 0;
 }
 
@@ -1931,8 +1936,8 @@ static void add_unmap(struct dmar_domain *dom, struct iova *iova)
 	spin_unlock_irqrestore(&async_umap_flush_lock, flags);
 }
 
-static void intel_unmap_single(struct device *dev, dma_addr_t dev_addr,
-	size_t size, int dir)
+void intel_unmap_single(struct device *dev, dma_addr_t dev_addr, size_t size,
+			int dir)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct dmar_domain *domain;
@@ -1948,11 +1953,11 @@ static void intel_unmap_single(struct device *dev, dma_addr_t dev_addr,
 	if (!iova)
 		return;
 
-	start_addr = iova->pfn_lo << PAGE_SHIFT_4K;
+	start_addr = iova->pfn_lo << PAGE_SHIFT;
 	size = aligned_size((u64)dev_addr, size);
 
 	pr_debug("Device %s unmapping: %lx@%llx\n",
-		pci_name(pdev), size, (u64)start_addr);
+		pci_name(pdev), size, (unsigned long long)start_addr);
 
 	/*  clear the whole page */
 	dma_pte_clear_range(domain, start_addr, start_addr + size);
@@ -1960,7 +1965,7 @@ static void intel_unmap_single(struct device *dev, dma_addr_t dev_addr,
 	dma_pte_free_pagetable(domain, start_addr, start_addr + size);
 	if (intel_iommu_strict) {
 		if (iommu_flush_iotlb_psi(domain->iommu,
-			domain->id, start_addr, size >> PAGE_SHIFT_4K, 0))
+			domain->id, start_addr, size >> VTD_PAGE_SHIFT, 0))
 			iommu_flush_write_buffer(domain->iommu);
 		/* free iova */
 		__free_iova(&domain->iovad, iova);
@@ -1973,13 +1978,13 @@ static void intel_unmap_single(struct device *dev, dma_addr_t dev_addr,
 	}
 }
 
-static void * intel_alloc_coherent(struct device *hwdev, size_t size,
-		       dma_addr_t *dma_handle, gfp_t flags)
+void *intel_alloc_coherent(struct device *hwdev, size_t size,
+			   dma_addr_t *dma_handle, gfp_t flags)
 {
 	void *vaddr;
 	int order;
 
-	size = PAGE_ALIGN_4K(size);
+	size = PAGE_ALIGN(size);
 	order = get_order(size);
 	flags &= ~(GFP_DMA | GFP_DMA32);
 
@@ -1995,12 +2000,12 @@ static void * intel_alloc_coherent(struct device *hwdev, size_t size,
 	return NULL;
 }
 
-static void intel_free_coherent(struct device *hwdev, size_t size,
-	void *vaddr, dma_addr_t dma_handle)
+void intel_free_coherent(struct device *hwdev, size_t size, void *vaddr,
+			 dma_addr_t dma_handle)
 {
 	int order;
 
-	size = PAGE_ALIGN_4K(size);
+	size = PAGE_ALIGN(size);
 	order = get_order(size);
 
 	intel_unmap_single(hwdev, dma_handle, size, DMA_BIDIRECTIONAL);
@@ -2008,8 +2013,9 @@ static void intel_free_coherent(struct device *hwdev, size_t size,
 }
 
 #define SG_ENT_VIRT_ADDRESS(sg)	(sg_virt((sg)))
-static void intel_unmap_sg(struct device *hwdev, struct scatterlist *sglist,
-	int nelems, int dir)
+
+void intel_unmap_sg(struct device *hwdev, struct scatterlist *sglist,
+		    int nelems, int dir)
 {
 	int i;
 	struct pci_dev *pdev = to_pci_dev(hwdev);
@@ -2033,7 +2039,7 @@ static void intel_unmap_sg(struct device *hwdev, struct scatterlist *sglist,
 		size += aligned_size((u64)addr, sg->length);
 	}
 
-	start_addr = iova->pfn_lo << PAGE_SHIFT_4K;
+	start_addr = iova->pfn_lo << PAGE_SHIFT;
 
 	/*  clear the whole page */
 	dma_pte_clear_range(domain, start_addr, start_addr + size);
@@ -2041,7 +2047,7 @@ static void intel_unmap_sg(struct device *hwdev, struct scatterlist *sglist,
 	dma_pte_free_pagetable(domain, start_addr, start_addr + size);
 
 	if (iommu_flush_iotlb_psi(domain->iommu, domain->id, start_addr,
-			size >> PAGE_SHIFT_4K, 0))
+			size >> VTD_PAGE_SHIFT, 0))
 		iommu_flush_write_buffer(domain->iommu);
 
 	/* free iova */
@@ -2062,8 +2068,8 @@ static int intel_nontranslate_map_sg(struct device *hddev,
 	return nelems;
 }
 
-static int intel_map_sg(struct device *hwdev, struct scatterlist *sglist,
-				int nelems, int dir)
+int intel_map_sg(struct device *hwdev, struct scatterlist *sglist, int nelems,
+		 int dir)
 {
 	void *addr;
 	int i;
@@ -2107,14 +2113,14 @@ static int intel_map_sg(struct device *hwdev, struct scatterlist *sglist,
 	if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL)
 		prot |= DMA_PTE_WRITE;
 
-	start_addr = iova->pfn_lo << PAGE_SHIFT_4K;
+	start_addr = iova->pfn_lo << PAGE_SHIFT;
 	offset = 0;
 	for_each_sg(sglist, sg, nelems, i) {
 		addr = SG_ENT_VIRT_ADDRESS(sg);
 		addr = (void *)virt_to_phys(addr);
 		size = aligned_size((u64)addr, sg->length);
 		ret = domain_page_mapping(domain, start_addr + offset,
-			((u64)addr) & PAGE_MASK_4K,
+			((u64)addr) & PAGE_MASK,
 			size, prot);
 		if (ret) {
 			/*  clear the page */
@@ -2128,14 +2134,14 @@ static int intel_map_sg(struct device *hwdev, struct scatterlist *sglist,
 			return 0;
 		}
 		sg->dma_address = start_addr + offset +
-				((u64)addr & (~PAGE_MASK_4K));
+				((u64)addr & (~PAGE_MASK));
 		sg->dma_length = sg->length;
 		offset += size;
 	}
 
 	/* it's a non-present to present mapping */
 	if (iommu_flush_iotlb_psi(domain->iommu, domain->id,
-			start_addr, offset >> PAGE_SHIFT_4K, 1))
+			start_addr, offset >> VTD_PAGE_SHIFT, 1))
 		iommu_flush_write_buffer(domain->iommu);
 	return nelems;
 }
@@ -2175,7 +2181,6 @@ static inline int iommu_devinfo_cache_init(void)
 					 sizeof(struct device_domain_info),
 					 0,
 					 SLAB_HWCACHE_ALIGN,
-
 					 NULL);
 	if (!iommu_devinfo_cache) {
 		printk(KERN_ERR "Couldn't create devinfo cache\n");
@@ -2193,7 +2198,6 @@ static inline int iommu_iova_cache_init(void)
 					 sizeof(struct iova),
 					 0,
 					 SLAB_HWCACHE_ALIGN,
-
 					 NULL);
 	if (!iommu_iova_cache) {
 		printk(KERN_ERR "Couldn't create iova cache\n");
@@ -2322,7 +2326,7 @@ void intel_iommu_domain_exit(struct dmar_domain *domain)
 		return;
 
 	end = DOMAIN_MAX_ADDR(domain->gaw);
-	end = end & (~PAGE_MASK_4K);
+	end = end & (~VTD_PAGE_MASK);
 
 	/* clear ptes */
 	dma_pte_clear_range(domain, 0, end);
@@ -2418,6 +2422,6 @@ u64 intel_iommu_iova_to_pfn(struct dmar_domain *domain, u64 iova)
 	if (pte)
 		pfn = dma_pte_addr(*pte);
 
-	return pfn >> PAGE_SHIFT_4K;
+	return pfn >> VTD_PAGE_SHIFT;
 }
 EXPORT_SYMBOL_GPL(intel_iommu_iova_to_pfn);
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index e872ac9..832175d 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -35,6 +35,20 @@ static void __devinit quirk_mellanox_tavor(struct pci_dev *dev)
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_MELLANOX,PCI_DEVICE_ID_MELLANOX_TAVOR,quirk_mellanox_tavor);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_MELLANOX,PCI_DEVICE_ID_MELLANOX_TAVOR_BRIDGE,quirk_mellanox_tavor);
 
+/* Many VIA bridges seem to corrupt data for DAC. Disable it here */
+int forbid_dac __read_mostly;
+EXPORT_SYMBOL(forbid_dac);
+
+static __devinit void via_no_dac(struct pci_dev *dev)
+{
+	if ((dev->class >> 8) == PCI_CLASS_BRIDGE_PCI && forbid_dac == 0) {
+		dev_info(&dev->dev,
+			"VIA PCI bridge detected. Disabling DAC.\n");
+		forbid_dac = 1;
+	}
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID, via_no_dac);
+
 /* Deal with broken BIOS'es that neglect to enable passive release,
    which can cause problems in combination with the 82441FX/PPro MTRRs */
 static void quirk_passive_release(struct pci_dev *dev)