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iommu/amd: Add workaround for event log erratum

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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: Joerg Roedel <joerg.roedel@amd.com>
This commit is contained in:
Joerg Roedel 2012-04-12 14:12:00 +02:00
parent a3b9312143
commit 3d06fca8d2
1 changed files with 23 additions and 6 deletions
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29
drivers/iommu/amd_iommu.c
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@ -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)