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Commit 49a0429e authored by Keshavamurthy, Anil S's avatar Keshavamurthy, Anil S Committed by Linus Torvalds
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Intel IOMMU: Iommu floppy workaround 



This config option (DMAR_FLPY_WA) sets up 1:1 mapping for the floppy device so
that the floppy device which does not use DMA api's will continue to work.

Once the floppy driver starts using DMA api's this config option can be turn
off or this patch can be yanked out of kernel at that time.

[akpm@linux-foundation.org: cleanups, rename things, build fix]
[jengelh@computergmbh.de: Kconfig fixes]
Signed-off-by: default avatarAnil 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: default avatarJan Engelhardt <jengelh@gmx.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e820482c

arch/x86_64/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -772,6 +772,16 @@ config DMAR_GFX_WA 
	 all the OS-visible memory. Hence the driver can continue

	 to use physical addresses for DMA.



config DMAR_FLOPPY_WA

	bool

	depends on DMAR

	default y

	help

	 Floppy disk drivers are know to bypass DMA API calls

	 thereby failing to work when IOMMU is enabled. This

	 workaround will setup a 1:1 mapping for the first

	 16M to make floppy (an ISA device) work.



source "drivers/pci/pcie/Kconfig"



source "drivers/pci/Kconfig"

drivers/pci/intel-iommu.c

+27 −0
Original line number Diff line number Diff line
@@ -1632,6 +1632,31 @@ static void __init iommu_prepare_gfx_mapping(void) 
}

#endif



#ifdef CONFIG_DMAR_FLOPPY_WA

static inline void iommu_prepare_isa(void)

{

	struct pci_dev *pdev;

	int ret;



	pdev = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, NULL);

	if (!pdev)

		return;



	printk(KERN_INFO "IOMMU: Prepare 0-16M unity mapping for LPC\n");

	ret = iommu_prepare_identity_map(pdev, 0, 16*1024*1024);



	if (ret)

		printk("IOMMU: Failed to create 0-64M identity map, "

			"floppy might not work\n");



}

#else

static inline void iommu_prepare_isa(void)

{

	return;

}

#endif /* !CONFIG_DMAR_FLPY_WA */



int __init init_dmars(void)

{

	struct dmar_drhd_unit *drhd;
@@ -1697,6 +1722,8 @@ int __init init_dmars(void) 


	iommu_prepare_gfx_mapping();



	iommu_prepare_isa();



	/*

	 * for each drhd

	 *   enable fault log