Implement a stall timer which fails H2G CTBs once a period of time
with no forward progress is reached to prevent deadlock.
v2:
(Michal)
- Improve error message in ct_deadlock()
- Set broken when ct_deadlock() returns true
- Return -EPIPE on ct_deadlock()
Signed-off-by: John Harrison <john.c.harri...@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospu...@intel.com>
Signed-off-by: Matthew Brost <matthew.br...@intel.com>
---
drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 62 ++++++++++++++++++++---
drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h | 4 ++
2 files changed, 59 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
index 90ee95a240e8..8f553f7f9619 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
@@ -319,6 +319,7 @@ int intel_guc_ct_enable(struct intel_guc_ct *ct)
goto err_deregister;
ct->enabled = true;
+ ct->stall_time = KTIME_MAX;
return 0;
@@ -391,9 +392,6 @@ static int ct_write(struct intel_guc_ct *ct,
u32 *cmds = ctb->cmds;
unsigned int i;
- if (unlikely(ctb->broken))
- return -EPIPE;
-
if (unlikely(desc->status))
goto corrupted;
@@ -509,6 +507,25 @@ static int wait_for_ct_request_update(struct ct_request
*req, u32 *status)
return err;
}
+#define GUC_CTB_TIMEOUT_MS 1500
+static inline bool ct_deadlocked(struct intel_guc_ct *ct)
+{
+ long timeout = GUC_CTB_TIMEOUT_MS;
+ bool ret = ktime_ms_delta(ktime_get(), ct->stall_time) > timeout;
+
+ if (unlikely(ret)) {
+ struct guc_ct_buffer_desc *send = ct->ctbs.send.desc;
+ struct guc_ct_buffer_desc *recv = ct->ctbs.send.desc;
+
+ CT_ERROR(ct, "Communication stalled for %lld, desc
status=%#x,%#x\n",
+ ktime_ms_delta(ktime_get(), ct->stall_time),
+ send->status, recv->status);
+ ct->ctbs.send.broken = true;
+ }
+
+ return ret;
+}
+
static inline bool h2g_has_room(struct intel_guc_ct_buffer *ctb, u32 len_dw)
{
struct guc_ct_buffer_desc *desc = ctb->desc;
@@ -520,6 +537,26 @@ static inline bool h2g_has_room(struct intel_guc_ct_buffer
*ctb, u32 len_dw)
return space >= len_dw;
}
+static int has_room_nb(struct intel_guc_ct *ct, u32 len_dw)
+{
+ struct intel_guc_ct_buffer *ctb = &ct->ctbs.send;
+
+ lockdep_assert_held(&ct->ctbs.send.lock);
+
+ if (unlikely(!h2g_has_room(ctb, len_dw))) {
+ if (ct->stall_time == KTIME_MAX)
+ ct->stall_time = ktime_get();
+
+ if (unlikely(ct_deadlocked(ct)))
+ return -EPIPE;
+ else
+ return -EBUSY;
+ }
+
+ ct->stall_time = KTIME_MAX;
+ return 0;
+}
+
static int ct_send_nb(struct intel_guc_ct *ct,
const u32 *action,
u32 len,
@@ -530,13 +567,14 @@ static int ct_send_nb(struct intel_guc_ct *ct,
u32 fence;
int ret;
+ if (unlikely(ctb->broken))
+ return -EPIPE;
+
spin_lock_irqsave(&ctb->lock, spin_flags);
- ret = h2g_has_room(ctb, len + GUC_CTB_HDR_LEN);
- if (unlikely(!ret)) {
- ret = -EBUSY;
+ ret = has_room_nb(ct, len + GUC_CTB_HDR_LEN);
+ if (unlikely(ret))
goto out;
- }
fence = ct_get_next_fence(ct);
ret = ct_write(ct, action, len, fence, flags);
@@ -571,6 +609,9 @@ static int ct_send(struct intel_guc_ct *ct,
GEM_BUG_ON(!response_buf && response_buf_size);
might_sleep();
+ if (unlikely(ctb->broken))
+ return -EPIPE;
+
/*
* We use a lazy spin wait loop here as we believe that if the CT
* buffers are sized correctly the flow control condition should be
@@ -579,8 +620,13 @@ static int ct_send(struct intel_guc_ct *ct,
retry:
spin_lock_irqsave(&ctb->lock, flags);
if (unlikely(!h2g_has_room(ctb, len + GUC_CTB_HDR_LEN))) {
+ if (ct->stall_time == KTIME_MAX)
+ ct->stall_time = ktime_get();
spin_unlock_irqrestore(&ctb->lock, flags);
+ if (unlikely(ct_deadlocked(ct)))
+ return -EPIPE;
+
if (msleep_interruptible(sleep_period_ms))
return -EINTR;
sleep_period_ms = sleep_period_ms << 1;
@@ -588,6 +634,8 @@ static int ct_send(struct intel_guc_ct *ct,
goto retry;
}
+ ct->stall_time = KTIME_MAX;
+
fence = ct_get_next_fence(ct);
request.fence = fence;
request.status = 0;
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h
b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h
index f6a4d5b33467..c9d6ae7848a7 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h
@@ -9,6 +9,7 @@
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
+#include <linux/ktime.h>
#include "intel_guc_fwif.h"
@@ -68,6 +69,9 @@ struct intel_guc_ct {
struct list_head incoming; /* incoming requests */
struct work_struct worker; /* handler for incoming requests */
} requests;
+
+ /** @stall_time: time of first time a CTB submission is stalled */
+ ktime_t stall_time;
};
void intel_guc_ct_init_early(struct intel_guc_ct *ct);
--
2.28.0
