[ 01/82] iommu/amd: Add workaround for event log erratum
From: Ben Hutchings <hidden>
Date: 2012-06-08 05:06:47
Also in:
lkml
Subsystem:
iommu subsystem, the rest · Maintainers:
Joerg Roedel, Will Deacon, Linus Torvalds
3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Joerg Roedel <redacted> commit 3d06fca8d2aa3543030e40b95f1d62f9f5a03540 upstream. 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. Signed-off-by: Joerg Roedel <redacted> Signed-off-by: Ben Hutchings <redacted> --- drivers/iommu/amd_iommu.c | 29 +++++++++++++++++++++++------ 1 file changed, 23 insertions(+), 6 deletions(-)
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 08f3eec..d90a421 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c@@ -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)