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Commit 3d06fca8 authored by Joerg Roedel's avatar Joerg Roedel
Browse files

iommu/amd: Add workaround for event log erratum 



Due to a recent erratum it can happen that the head pointer
of the event-log is updated before the actual event-log
entry is written. This patch implements the recommended
workaround.

Cc: stable@vger.kernel.org	# all stable kernels
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
parent a3b93121

drivers/iommu/amd_iommu.c

+23 −6
Original line number Diff line number Diff line
@@ -450,12 +450,27 @@ static void dump_command(unsigned long phys_addr) 


static void iommu_print_event(struct amd_iommu *iommu, void *__evt)

{

	u32 *event = __evt;

	int type  = (event[1] >> EVENT_TYPE_SHIFT)  & EVENT_TYPE_MASK;

	int devid = (event[0] >> EVENT_DEVID_SHIFT) & EVENT_DEVID_MASK;

	int domid = (event[1] >> EVENT_DOMID_SHIFT) & EVENT_DOMID_MASK;

	int flags = (event[1] >> EVENT_FLAGS_SHIFT) & EVENT_FLAGS_MASK;

	u64 address = (u64)(((u64)event[3]) << 32) | event[2];

	int type, devid, domid, flags;

	volatile u32 *event = __evt;

	int count = 0;

	u64 address;



retry:

	type    = (event[1] >> EVENT_TYPE_SHIFT)  & EVENT_TYPE_MASK;

	devid   = (event[0] >> EVENT_DEVID_SHIFT) & EVENT_DEVID_MASK;

	domid   = (event[1] >> EVENT_DOMID_SHIFT) & EVENT_DOMID_MASK;

	flags   = (event[1] >> EVENT_FLAGS_SHIFT) & EVENT_FLAGS_MASK;

	address = (u64)(((u64)event[3]) << 32) | event[2];



	if (type == 0) {

		/* Did we hit the erratum? */

		if (++count == LOOP_TIMEOUT) {

			pr_err("AMD-Vi: No event written to event log\n");

			return;

		}

		udelay(1);

		goto retry;

	}



	printk(KERN_ERR "AMD-Vi: Event logged [");
@@ -508,6 +523,8 @@ static void iommu_print_event(struct amd_iommu *iommu, void *__evt) 
	default:

		printk(KERN_ERR "UNKNOWN type=0x%02x]\n", type);

	}



	memset(__evt, 0, 4 * sizeof(u32));

}



static void iommu_poll_events(struct amd_iommu *iommu)