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Commit c5cca146 authored by Joerg Roedel's avatar Joerg Roedel
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x86/amd-iommu: Workaround for erratum 63 



There is an erratum for IOMMU hardware which documents
undefined behavior when forwarding SMI requests from
peripherals and the DTE of that peripheral has a sysmgt
value of 01b. This problem caused weird IO_PAGE_FAULTS in my
case.
This patch implements the suggested workaround for that
erratum into the AMD IOMMU driver.  The erratum is
documented with number 63.

Cc: stable@kernel.org
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
parent c7084b35

arch/x86/include/asm/amd_iommu.h

+1 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ extern irqreturn_t amd_iommu_int_handler(int irq, void *data); 
extern void amd_iommu_flush_all_domains(void);

extern void amd_iommu_flush_all_devices(void);

extern void amd_iommu_shutdown(void);

extern void amd_iommu_apply_erratum_63(u16 devid);

#else

static inline int amd_iommu_init(void) { return -ENODEV; }

static inline void amd_iommu_detect(void) { }

arch/x86/kernel/amd_iommu.c

+2 −0
Original line number Diff line number Diff line
@@ -1114,6 +1114,8 @@ static void __detach_device(struct protection_domain *domain, u16 devid) 
	amd_iommu_dev_table[devid].data[1] = 0;

	amd_iommu_dev_table[devid].data[2] = 0;



	amd_iommu_apply_erratum_63(devid);



	/* decrease reference counter */

	domain->dev_cnt -= 1;

arch/x86/kernel/amd_iommu_init.c

+22 −0
Original line number Diff line number Diff line
@@ -509,6 +509,26 @@ static void set_dev_entry_bit(u16 devid, u8 bit) 
	amd_iommu_dev_table[devid].data[i] |= (1 << _bit);

}



static int get_dev_entry_bit(u16 devid, u8 bit)

{

	int i = (bit >> 5) & 0x07;

	int _bit = bit & 0x1f;



	return (amd_iommu_dev_table[devid].data[i] & (1 << _bit)) >> _bit;

}





void amd_iommu_apply_erratum_63(u16 devid)

{

	int sysmgt;



	sysmgt = get_dev_entry_bit(devid, DEV_ENTRY_SYSMGT1) |

		 (get_dev_entry_bit(devid, DEV_ENTRY_SYSMGT2) << 1);



	if (sysmgt == 0x01)

		set_dev_entry_bit(devid, DEV_ENTRY_IW);

}



/* Writes the specific IOMMU for a device into the rlookup table */

static void __init set_iommu_for_device(struct amd_iommu *iommu, u16 devid)

{
@@ -537,6 +557,8 @@ static void __init set_dev_entry_from_acpi(struct amd_iommu *iommu, 
	if (flags & ACPI_DEVFLAG_LINT1)

		set_dev_entry_bit(devid, DEV_ENTRY_LINT1_PASS);



	amd_iommu_apply_erratum_63(devid);



	set_iommu_for_device(iommu, devid);

}