| Message ID | 20210624070516.21893-7-matthew.brost@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | GuC submission support | expand |
On 24.06.2021 09:04, Matthew Brost wrote: > CTB writes are now in the path of command submission and should be > optimized for performance. Rather than reading CTB descriptor values > (e.g. head, tail) which could result in accesses across the PCIe bus, > store shadow local copies and only read/write the descriptor values when > absolutely necessary. Also store the current space in the each channel > locally. > > Signed-off-by: John Harrison <John.C.Harrison@Intel.com> > Signed-off-by: Matthew Brost <matthew.brost@intel.com> > --- > drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 76 ++++++++++++++--------- > drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h | 6 ++ > 2 files changed, 51 insertions(+), 31 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 27ec30b5ef47..1fd5c69358ef 100644 > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c > @@ -130,6 +130,10 @@ static void guc_ct_buffer_desc_init(struct guc_ct_buffer_desc *desc) > static void guc_ct_buffer_reset(struct intel_guc_ct_buffer *ctb) > { > ctb->broken = false; > + ctb->tail = 0; > + ctb->head = 0; > + ctb->space = CIRC_SPACE(ctb->tail, ctb->head, ctb->size); > + > guc_ct_buffer_desc_init(ctb->desc); > } > > @@ -383,10 +387,8 @@ static int ct_write(struct intel_guc_ct *ct, > { > struct intel_guc_ct_buffer *ctb = &ct->ctbs.send; > struct guc_ct_buffer_desc *desc = ctb->desc; > - u32 head = desc->head; > - u32 tail = desc->tail; > + u32 tail = ctb->tail; > u32 size = ctb->size; > - u32 used; > u32 header; > u32 hxg; > u32 *cmds = ctb->cmds; > @@ -398,25 +400,14 @@ static int ct_write(struct intel_guc_ct *ct, > if (unlikely(desc->status)) > goto corrupted; > > - if (unlikely((tail | head) >= size)) { > +#ifdef CONFIG_DRM_I915_DEBUG_GUC since we are caching tail, we may want to check if it's sill correct: tail = READ_ONCE(desc->tail); if (unlikely(tail != ctb->tail)) { CT_ERROR(ct, "Tail was modified %u != %u\n", tail, ctb->tail); desc->status |= GUC_CTB_STATUS_MISMATCH; goto corrupted; } and since we own the tail then we can be more strict: GEM_BUG_ON(tail > size); and then finally just check GuC head: head = READ_ONCE(desc->head); if (unlikely(head >= size)) { ... > + if (unlikely((desc->tail | desc->head) >= size)) { > CT_ERROR(ct, "Invalid offsets head=%u tail=%u (size=%u)\n", > - head, tail, size); > + desc->head, desc->tail, size); > desc->status |= GUC_CTB_STATUS_OVERFLOW; > goto corrupted; > } > - > - /* > - * tail == head condition indicates empty. GuC FW does not support > - * using up the entire buffer to get tail == head meaning full. > - */ > - if (tail < head) > - used = (size - head) + tail; > - else > - used = tail - head; > - > - /* make sure there is a space including extra dw for the fence */ > - if (unlikely(used + len + 1 >= size)) > - return -ENOSPC; > +#endif > > /* > * dw0: CT header (including fence) > @@ -457,7 +448,9 @@ static int ct_write(struct intel_guc_ct *ct, > write_barrier(ct); > > /* now update descriptor */ > + ctb->tail = tail; > WRITE_ONCE(desc->tail, tail); > + ctb->space -= len + 1; this magic "1" is likely GUC_CTB_MSG_MIN_LEN, right ? > > return 0; > > @@ -473,7 +466,7 @@ static int ct_write(struct intel_guc_ct *ct, > * @req: pointer to pending request > * @status: placeholder for status > * > - * For each sent request, Guc shall send bac CT response message. > + * For each sent request, GuC shall send back CT response message. > * Our message handler will update status of tracked request once > * response message with given fence is received. Wait here and > * check for valid response status value. > @@ -520,24 +513,35 @@ static inline bool ct_deadlocked(struct intel_guc_ct *ct) > return ret; > } > > -static inline bool h2g_has_room(struct intel_guc_ct_buffer *ctb, u32 len_dw) > +static inline bool h2g_has_room(struct intel_guc_ct *ct, u32 len_dw) > { > - struct guc_ct_buffer_desc *desc = ctb->desc; > - u32 head = READ_ONCE(desc->head); > + struct intel_guc_ct_buffer *ctb = &ct->ctbs.send; > + u32 head; > u32 space; > > - space = CIRC_SPACE(desc->tail, head, ctb->size); > + if (ctb->space >= len_dw) > + return true; > + > + head = READ_ONCE(ctb->desc->head); > + if (unlikely(head > ctb->size)) { > + CT_ERROR(ct, "Corrupted descriptor head=%u tail=%u size=%u\n", > + ctb->desc->head, ctb->desc->tail, ctb->size); > + ctb->desc->status |= GUC_CTB_STATUS_OVERFLOW; > + ctb->broken = true; > + return false; > + } > + > + space = CIRC_SPACE(ctb->tail, head, ctb->size); > + ctb->space = space; maybe here we could mark stall_time ? if (space >= len_dw) return true; if (ct->stall_time == KTIME_MAX) ct->stall_time = ktime_get(); return false; > > return space >= len_dw; btw, maybe to avoid filling CTB to the last dword, this should be space > len_dw note the earlier comment: /* * tail == head condition indicates empty. GuC FW does not support * using up the entire buffer to get tail == head meaning full. */ > } > > 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 (unlikely(!h2g_has_room(ct, len_dw))) { > if (ct->stall_time == KTIME_MAX) > ct->stall_time = ktime_get(); > > @@ -606,10 +610,10 @@ static int ct_send(struct intel_guc_ct *ct, > */ > retry: > spin_lock_irqsave(&ct->ctbs.send.lock, flags); > - if (unlikely(!h2g_has_room(ctb, len + 1))) { > + if (unlikely(!h2g_has_room(ct, len + 1))) { > if (ct->stall_time == KTIME_MAX) > ct->stall_time = ktime_get(); > - spin_unlock_irqrestore(&ct->ctbs.send.lock, flags); > + spin_unlock_irqrestore(&ctb->lock, flags); > > if (unlikely(ct_deadlocked(ct))) > return -EIO; > @@ -632,7 +636,7 @@ static int ct_send(struct intel_guc_ct *ct, > > err = ct_write(ct, action, len, fence, 0); > > - spin_unlock_irqrestore(&ct->ctbs.send.lock, flags); > + spin_unlock_irqrestore(&ctb->lock, flags); > > if (unlikely(err)) > goto unlink; > @@ -720,7 +724,7 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) > { > struct intel_guc_ct_buffer *ctb = &ct->ctbs.recv; > struct guc_ct_buffer_desc *desc = ctb->desc; > - u32 head = desc->head; > + u32 head = ctb->head; > u32 tail = desc->tail; > u32 size = ctb->size; > u32 *cmds = ctb->cmds; > @@ -735,12 +739,21 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) > if (unlikely(desc->status)) > goto corrupted; > > - if (unlikely((tail | head) >= size)) { > +#ifdef CONFIG_DRM_I915_DEBUG_GUC as above we may want to check if our cached head was not modified > + if (unlikely((desc->tail | desc->head) >= size)) { > CT_ERROR(ct, "Invalid offsets head=%u tail=%u (size=%u)\n", > head, tail, size); > desc->status |= GUC_CTB_STATUS_OVERFLOW; > goto corrupted; > } > +#else > + if (unlikely((tail | ctb->head) >= size)) { > + CT_ERROR(ct, "Invalid offsets head=%u tail=%u (size=%u)\n", > + head, tail, size); > + desc->status |= GUC_CTB_STATUS_OVERFLOW; > + goto corrupted; > + } > +#endif > > /* tail == head condition indicates empty */ > available = tail - head; > @@ -790,6 +803,7 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) > } > CT_DEBUG(ct, "received %*ph\n", 4 * len, (*msg)->msg); > > + ctb->head = head; > /* now update descriptor */ > WRITE_ONCE(desc->head, head); > > 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 55ef7c52472f..9924335e2ee6 100644 > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h > @@ -33,6 +33,9 @@ struct intel_guc; > * @desc: pointer to the buffer descriptor > * @cmds: pointer to the commands buffer > * @size: size of the commands buffer in dwords > + * @head: local shadow copy of head in dwords > + * @tail: local shadow copy of tail in dwords > + * @space: local shadow copy of space in dwords > * @broken: flag to indicate if descriptor data is broken > */ > struct intel_guc_ct_buffer { > @@ -40,6 +43,9 @@ struct intel_guc_ct_buffer { > struct guc_ct_buffer_desc *desc; > u32 *cmds; > u32 size; > + u32 tail; > + u32 head; > + u32 space; in later patch this is changing to atomic_t maybe we can start with it ? > bool broken; > }; > >
On Fri, Jun 25, 2021 at 03:09:29PM +0200, Michal Wajdeczko wrote: > > > On 24.06.2021 09:04, Matthew Brost wrote: > > CTB writes are now in the path of command submission and should be > > optimized for performance. Rather than reading CTB descriptor values > > (e.g. head, tail) which could result in accesses across the PCIe bus, > > store shadow local copies and only read/write the descriptor values when > > absolutely necessary. Also store the current space in the each channel > > locally. > > > > Signed-off-by: John Harrison <John.C.Harrison@Intel.com> > > Signed-off-by: Matthew Brost <matthew.brost@intel.com> > > --- > > drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 76 ++++++++++++++--------- > > drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h | 6 ++ > > 2 files changed, 51 insertions(+), 31 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 27ec30b5ef47..1fd5c69358ef 100644 > > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c > > @@ -130,6 +130,10 @@ static void guc_ct_buffer_desc_init(struct guc_ct_buffer_desc *desc) > > static void guc_ct_buffer_reset(struct intel_guc_ct_buffer *ctb) > > { > > ctb->broken = false; > > + ctb->tail = 0; > > + ctb->head = 0; > > + ctb->space = CIRC_SPACE(ctb->tail, ctb->head, ctb->size); > > + > > guc_ct_buffer_desc_init(ctb->desc); > > } > > > > @@ -383,10 +387,8 @@ static int ct_write(struct intel_guc_ct *ct, > > { > > struct intel_guc_ct_buffer *ctb = &ct->ctbs.send; > > struct guc_ct_buffer_desc *desc = ctb->desc; > > - u32 head = desc->head; > > - u32 tail = desc->tail; > > + u32 tail = ctb->tail; > > u32 size = ctb->size; > > - u32 used; > > u32 header; > > u32 hxg; > > u32 *cmds = ctb->cmds; > > @@ -398,25 +400,14 @@ static int ct_write(struct intel_guc_ct *ct, > > if (unlikely(desc->status)) > > goto corrupted; > > > > - if (unlikely((tail | head) >= size)) { > > +#ifdef CONFIG_DRM_I915_DEBUG_GUC > > since we are caching tail, we may want to check if it's sill correct: > > tail = READ_ONCE(desc->tail); > if (unlikely(tail != ctb->tail)) { > CT_ERROR(ct, "Tail was modified %u != %u\n", > tail, ctb->tail); > desc->status |= GUC_CTB_STATUS_MISMATCH; > goto corrupted; > } > > and since we own the tail then we can be more strict: > > GEM_BUG_ON(tail > size); > > and then finally just check GuC head: > > head = READ_ONCE(desc->head); > if (unlikely(head >= size)) { > ... > Sure, but still hidden behind CONFIG_DRM_I915_DEBUG_GUC, right? > > + if (unlikely((desc->tail | desc->head) >= size)) { > > CT_ERROR(ct, "Invalid offsets head=%u tail=%u (size=%u)\n", > > - head, tail, size); > > + desc->head, desc->tail, size); > > desc->status |= GUC_CTB_STATUS_OVERFLOW; > > goto corrupted; > > } > > - > > - /* > > - * tail == head condition indicates empty. GuC FW does not support > > - * using up the entire buffer to get tail == head meaning full. > > - */ > > - if (tail < head) > > - used = (size - head) + tail; > > - else > > - used = tail - head; > > - > > - /* make sure there is a space including extra dw for the fence */ > > - if (unlikely(used + len + 1 >= size)) > > - return -ENOSPC; > > +#endif > > > > /* > > * dw0: CT header (including fence) > > @@ -457,7 +448,9 @@ static int ct_write(struct intel_guc_ct *ct, > > write_barrier(ct); > > > > /* now update descriptor */ > > + ctb->tail = tail; > > WRITE_ONCE(desc->tail, tail); > > + ctb->space -= len + 1; > > this magic "1" is likely GUC_CTB_MSG_MIN_LEN, right ? > Yes. > > > > return 0; > > > > @@ -473,7 +466,7 @@ static int ct_write(struct intel_guc_ct *ct, > > * @req: pointer to pending request > > * @status: placeholder for status > > * > > - * For each sent request, Guc shall send bac CT response message. > > + * For each sent request, GuC shall send back CT response message. > > * Our message handler will update status of tracked request once > > * response message with given fence is received. Wait here and > > * check for valid response status value. > > @@ -520,24 +513,35 @@ static inline bool ct_deadlocked(struct intel_guc_ct *ct) > > return ret; > > } > > > > -static inline bool h2g_has_room(struct intel_guc_ct_buffer *ctb, u32 len_dw) > > +static inline bool h2g_has_room(struct intel_guc_ct *ct, u32 len_dw) > > { > > - struct guc_ct_buffer_desc *desc = ctb->desc; > > - u32 head = READ_ONCE(desc->head); > > + struct intel_guc_ct_buffer *ctb = &ct->ctbs.send; > > + u32 head; > > u32 space; > > > > - space = CIRC_SPACE(desc->tail, head, ctb->size); > > + if (ctb->space >= len_dw) > > + return true; > > + > > + head = READ_ONCE(ctb->desc->head); > > + if (unlikely(head > ctb->size)) { > > + CT_ERROR(ct, "Corrupted descriptor head=%u tail=%u size=%u\n", > > + ctb->desc->head, ctb->desc->tail, ctb->size); > > + ctb->desc->status |= GUC_CTB_STATUS_OVERFLOW; > > + ctb->broken = true; > > + return false; > > + } > > + > > + space = CIRC_SPACE(ctb->tail, head, ctb->size); > > + ctb->space = space; > > maybe here we could mark stall_time ? > > if (space >= len_dw) > return true; > > if (ct->stall_time == KTIME_MAX) > ct->stall_time = ktime_get(); > return false; > No. See my eariler comment [1] about why I'd rather leave this to the caller. [1] https://patchwork.freedesktop.org/patch/440703/?series=91840&rev=1 > > > > return space >= len_dw; > > btw, maybe to avoid filling CTB to the last dword, this should be > > space > len_dw > CIRC_SPACE leaves an extra DW already. > note the earlier comment: > > /* > * tail == head condition indicates empty. GuC FW does not support > * using up the entire buffer to get tail == head meaning full. > */ > Yes, again CIRC_SPACE uses this same algorithm. Matt > > } > > > > 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 (unlikely(!h2g_has_room(ct, len_dw))) { > > if (ct->stall_time == KTIME_MAX) > > ct->stall_time = ktime_get(); > > > > @@ -606,10 +610,10 @@ static int ct_send(struct intel_guc_ct *ct, > > */ > > retry: > > spin_lock_irqsave(&ct->ctbs.send.lock, flags); > > - if (unlikely(!h2g_has_room(ctb, len + 1))) { > > + if (unlikely(!h2g_has_room(ct, len + 1))) { > > if (ct->stall_time == KTIME_MAX) > > ct->stall_time = ktime_get(); > > - spin_unlock_irqrestore(&ct->ctbs.send.lock, flags); > > + spin_unlock_irqrestore(&ctb->lock, flags); > > > > if (unlikely(ct_deadlocked(ct))) > > return -EIO; > > @@ -632,7 +636,7 @@ static int ct_send(struct intel_guc_ct *ct, > > > > err = ct_write(ct, action, len, fence, 0); > > > > - spin_unlock_irqrestore(&ct->ctbs.send.lock, flags); > > + spin_unlock_irqrestore(&ctb->lock, flags); > > > > if (unlikely(err)) > > goto unlink; > > @@ -720,7 +724,7 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) > > { > > struct intel_guc_ct_buffer *ctb = &ct->ctbs.recv; > > struct guc_ct_buffer_desc *desc = ctb->desc; > > - u32 head = desc->head; > > + u32 head = ctb->head; > > u32 tail = desc->tail; > > u32 size = ctb->size; > > u32 *cmds = ctb->cmds; > > @@ -735,12 +739,21 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) > > if (unlikely(desc->status)) > > goto corrupted; > > > > - if (unlikely((tail | head) >= size)) { > > +#ifdef CONFIG_DRM_I915_DEBUG_GUC > > as above we may want to check if our cached head was not modified > > > + if (unlikely((desc->tail | desc->head) >= size)) { > > CT_ERROR(ct, "Invalid offsets head=%u tail=%u (size=%u)\n", > > head, tail, size); > > desc->status |= GUC_CTB_STATUS_OVERFLOW; > > goto corrupted; > > } > > +#else > > + if (unlikely((tail | ctb->head) >= size)) { > > + CT_ERROR(ct, "Invalid offsets head=%u tail=%u (size=%u)\n", > > + head, tail, size); > > + desc->status |= GUC_CTB_STATUS_OVERFLOW; > > + goto corrupted; > > + } > > +#endif > > > > /* tail == head condition indicates empty */ > > available = tail - head; > > @@ -790,6 +803,7 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) > > } > > CT_DEBUG(ct, "received %*ph\n", 4 * len, (*msg)->msg); > > > > + ctb->head = head; > > /* now update descriptor */ > > WRITE_ONCE(desc->head, head); > > > > 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 55ef7c52472f..9924335e2ee6 100644 > > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h > > @@ -33,6 +33,9 @@ struct intel_guc; > > * @desc: pointer to the buffer descriptor > > * @cmds: pointer to the commands buffer > > * @size: size of the commands buffer in dwords > > + * @head: local shadow copy of head in dwords > > + * @tail: local shadow copy of tail in dwords > > + * @space: local shadow copy of space in dwords > > * @broken: flag to indicate if descriptor data is broken > > */ > > struct intel_guc_ct_buffer { > > @@ -40,6 +43,9 @@ struct intel_guc_ct_buffer { > > struct guc_ct_buffer_desc *desc; > > u32 *cmds; > > u32 size; > > + u32 tail; > > + u32 head; > > + u32 space; > > in later patch this is changing to atomic_t > maybe we can start with it ? > > > bool broken; > > }; > > > >
On Fri, Jun 25, 2021 at 03:09:29PM +0200, Michal Wajdeczko wrote: > > > On 24.06.2021 09:04, Matthew Brost wrote: > > CTB writes are now in the path of command submission and should be > > optimized for performance. Rather than reading CTB descriptor values > > (e.g. head, tail) which could result in accesses across the PCIe bus, > > store shadow local copies and only read/write the descriptor values when > > absolutely necessary. Also store the current space in the each channel > > locally. > > Missed two comments, addressed below. > > Signed-off-by: John Harrison <John.C.Harrison@Intel.com> > > Signed-off-by: Matthew Brost <matthew.brost@intel.com> > > --- > > drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 76 ++++++++++++++--------- > > drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h | 6 ++ > > 2 files changed, 51 insertions(+), 31 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 27ec30b5ef47..1fd5c69358ef 100644 > > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c > > @@ -130,6 +130,10 @@ static void guc_ct_buffer_desc_init(struct guc_ct_buffer_desc *desc) > > static void guc_ct_buffer_reset(struct intel_guc_ct_buffer *ctb) > > { > > ctb->broken = false; > > + ctb->tail = 0; > > + ctb->head = 0; > > + ctb->space = CIRC_SPACE(ctb->tail, ctb->head, ctb->size); > > + > > guc_ct_buffer_desc_init(ctb->desc); > > } > > > > @@ -383,10 +387,8 @@ static int ct_write(struct intel_guc_ct *ct, > > { > > struct intel_guc_ct_buffer *ctb = &ct->ctbs.send; > > struct guc_ct_buffer_desc *desc = ctb->desc; > > - u32 head = desc->head; > > - u32 tail = desc->tail; > > + u32 tail = ctb->tail; > > u32 size = ctb->size; > > - u32 used; > > u32 header; > > u32 hxg; > > u32 *cmds = ctb->cmds; > > @@ -398,25 +400,14 @@ static int ct_write(struct intel_guc_ct *ct, > > if (unlikely(desc->status)) > > goto corrupted; > > > > - if (unlikely((tail | head) >= size)) { > > +#ifdef CONFIG_DRM_I915_DEBUG_GUC > > since we are caching tail, we may want to check if it's sill correct: > > tail = READ_ONCE(desc->tail); > if (unlikely(tail != ctb->tail)) { > CT_ERROR(ct, "Tail was modified %u != %u\n", > tail, ctb->tail); > desc->status |= GUC_CTB_STATUS_MISMATCH; > goto corrupted; > } > > and since we own the tail then we can be more strict: > > GEM_BUG_ON(tail > size); > > and then finally just check GuC head: > > head = READ_ONCE(desc->head); > if (unlikely(head >= size)) { > ... > > > + if (unlikely((desc->tail | desc->head) >= size)) { > > CT_ERROR(ct, "Invalid offsets head=%u tail=%u (size=%u)\n", > > - head, tail, size); > > + desc->head, desc->tail, size); > > desc->status |= GUC_CTB_STATUS_OVERFLOW; > > goto corrupted; > > } > > - > > - /* > > - * tail == head condition indicates empty. GuC FW does not support > > - * using up the entire buffer to get tail == head meaning full. > > - */ > > - if (tail < head) > > - used = (size - head) + tail; > > - else > > - used = tail - head; > > - > > - /* make sure there is a space including extra dw for the fence */ > > - if (unlikely(used + len + 1 >= size)) > > - return -ENOSPC; > > +#endif > > > > /* > > * dw0: CT header (including fence) > > @@ -457,7 +448,9 @@ static int ct_write(struct intel_guc_ct *ct, > > write_barrier(ct); > > > > /* now update descriptor */ > > + ctb->tail = tail; > > WRITE_ONCE(desc->tail, tail); > > + ctb->space -= len + 1; > > this magic "1" is likely GUC_CTB_MSG_MIN_LEN, right ? > > > > > return 0; > > > > @@ -473,7 +466,7 @@ static int ct_write(struct intel_guc_ct *ct, > > * @req: pointer to pending request > > * @status: placeholder for status > > * > > - * For each sent request, Guc shall send bac CT response message. > > + * For each sent request, GuC shall send back CT response message. > > * Our message handler will update status of tracked request once > > * response message with given fence is received. Wait here and > > * check for valid response status value. > > @@ -520,24 +513,35 @@ static inline bool ct_deadlocked(struct intel_guc_ct *ct) > > return ret; > > } > > > > -static inline bool h2g_has_room(struct intel_guc_ct_buffer *ctb, u32 len_dw) > > +static inline bool h2g_has_room(struct intel_guc_ct *ct, u32 len_dw) > > { > > - struct guc_ct_buffer_desc *desc = ctb->desc; > > - u32 head = READ_ONCE(desc->head); > > + struct intel_guc_ct_buffer *ctb = &ct->ctbs.send; > > + u32 head; > > u32 space; > > > > - space = CIRC_SPACE(desc->tail, head, ctb->size); > > + if (ctb->space >= len_dw) > > + return true; > > + > > + head = READ_ONCE(ctb->desc->head); > > + if (unlikely(head > ctb->size)) { > > + CT_ERROR(ct, "Corrupted descriptor head=%u tail=%u size=%u\n", > > + ctb->desc->head, ctb->desc->tail, ctb->size); > > + ctb->desc->status |= GUC_CTB_STATUS_OVERFLOW; > > + ctb->broken = true; > > + return false; > > + } > > + > > + space = CIRC_SPACE(ctb->tail, head, ctb->size); > > + ctb->space = space; > > maybe here we could mark stall_time ? > > if (space >= len_dw) > return true; > > if (ct->stall_time == KTIME_MAX) > ct->stall_time = ktime_get(); > return false; > > > > > return space >= len_dw; > > btw, maybe to avoid filling CTB to the last dword, this should be > > space > len_dw > > note the earlier comment: > > /* > * tail == head condition indicates empty. GuC FW does not support > * using up the entire buffer to get tail == head meaning full. > */ > > > } > > > > 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 (unlikely(!h2g_has_room(ct, len_dw))) { > > if (ct->stall_time == KTIME_MAX) > > ct->stall_time = ktime_get(); > > > > @@ -606,10 +610,10 @@ static int ct_send(struct intel_guc_ct *ct, > > */ > > retry: > > spin_lock_irqsave(&ct->ctbs.send.lock, flags); > > - if (unlikely(!h2g_has_room(ctb, len + 1))) { > > + if (unlikely(!h2g_has_room(ct, len + 1))) { > > if (ct->stall_time == KTIME_MAX) > > ct->stall_time = ktime_get(); > > - spin_unlock_irqrestore(&ct->ctbs.send.lock, flags); > > + spin_unlock_irqrestore(&ctb->lock, flags); > > > > if (unlikely(ct_deadlocked(ct))) > > return -EIO; > > @@ -632,7 +636,7 @@ static int ct_send(struct intel_guc_ct *ct, > > > > err = ct_write(ct, action, len, fence, 0); > > > > - spin_unlock_irqrestore(&ct->ctbs.send.lock, flags); > > + spin_unlock_irqrestore(&ctb->lock, flags); > > > > if (unlikely(err)) > > goto unlink; > > @@ -720,7 +724,7 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) > > { > > struct intel_guc_ct_buffer *ctb = &ct->ctbs.recv; > > struct guc_ct_buffer_desc *desc = ctb->desc; > > - u32 head = desc->head; > > + u32 head = ctb->head; > > u32 tail = desc->tail; > > u32 size = ctb->size; > > u32 *cmds = ctb->cmds; > > @@ -735,12 +739,21 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) > > if (unlikely(desc->status)) > > goto corrupted; > > > > - if (unlikely((tail | head) >= size)) { > > +#ifdef CONFIG_DRM_I915_DEBUG_GUC > > as above we may want to check if our cached head was not modified > Sure. > > + if (unlikely((desc->tail | desc->head) >= size)) { > > CT_ERROR(ct, "Invalid offsets head=%u tail=%u (size=%u)\n", > > head, tail, size); > > desc->status |= GUC_CTB_STATUS_OVERFLOW; > > goto corrupted; > > } > > +#else > > + if (unlikely((tail | ctb->head) >= size)) { > > + CT_ERROR(ct, "Invalid offsets head=%u tail=%u (size=%u)\n", > > + head, tail, size); > > + desc->status |= GUC_CTB_STATUS_OVERFLOW; > > + goto corrupted; > > + } > > +#endif > > > > /* tail == head condition indicates empty */ > > available = tail - head; > > @@ -790,6 +803,7 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) > > } > > CT_DEBUG(ct, "received %*ph\n", 4 * len, (*msg)->msg); > > > > + ctb->head = head; > > /* now update descriptor */ > > WRITE_ONCE(desc->head, head); > > > > 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 55ef7c52472f..9924335e2ee6 100644 > > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h > > @@ -33,6 +33,9 @@ struct intel_guc; > > * @desc: pointer to the buffer descriptor > > * @cmds: pointer to the commands buffer > > * @size: size of the commands buffer in dwords > > + * @head: local shadow copy of head in dwords > > + * @tail: local shadow copy of tail in dwords > > + * @space: local shadow copy of space in dwords > > * @broken: flag to indicate if descriptor data is broken > > */ > > struct intel_guc_ct_buffer { > > @@ -40,6 +43,9 @@ struct intel_guc_ct_buffer { > > struct guc_ct_buffer_desc *desc; > > u32 *cmds; > > u32 size; > > + u32 tail; > > + u32 head; > > + u32 space; > > in later patch this is changing to atomic_t > maybe we can start with it ? > I'd rather leave this as is. It doesn't make to use an atomic here but G2H credits patch makes it clear why we need an atomic. Matt > > bool broken; > > }; > > > >
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 27ec30b5ef47..1fd5c69358ef 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c @@ -130,6 +130,10 @@ static void guc_ct_buffer_desc_init(struct guc_ct_buffer_desc *desc) static void guc_ct_buffer_reset(struct intel_guc_ct_buffer *ctb) { ctb->broken = false; + ctb->tail = 0; + ctb->head = 0; + ctb->space = CIRC_SPACE(ctb->tail, ctb->head, ctb->size); + guc_ct_buffer_desc_init(ctb->desc); } @@ -383,10 +387,8 @@ static int ct_write(struct intel_guc_ct *ct, { struct intel_guc_ct_buffer *ctb = &ct->ctbs.send; struct guc_ct_buffer_desc *desc = ctb->desc; - u32 head = desc->head; - u32 tail = desc->tail; + u32 tail = ctb->tail; u32 size = ctb->size; - u32 used; u32 header; u32 hxg; u32 *cmds = ctb->cmds; @@ -398,25 +400,14 @@ static int ct_write(struct intel_guc_ct *ct, if (unlikely(desc->status)) goto corrupted; - if (unlikely((tail | head) >= size)) { +#ifdef CONFIG_DRM_I915_DEBUG_GUC + if (unlikely((desc->tail | desc->head) >= size)) { CT_ERROR(ct, "Invalid offsets head=%u tail=%u (size=%u)\n", - head, tail, size); + desc->head, desc->tail, size); desc->status |= GUC_CTB_STATUS_OVERFLOW; goto corrupted; } - - /* - * tail == head condition indicates empty. GuC FW does not support - * using up the entire buffer to get tail == head meaning full. - */ - if (tail < head) - used = (size - head) + tail; - else - used = tail - head; - - /* make sure there is a space including extra dw for the fence */ - if (unlikely(used + len + 1 >= size)) - return -ENOSPC; +#endif /* * dw0: CT header (including fence) @@ -457,7 +448,9 @@ static int ct_write(struct intel_guc_ct *ct, write_barrier(ct); /* now update descriptor */ + ctb->tail = tail; WRITE_ONCE(desc->tail, tail); + ctb->space -= len + 1; return 0; @@ -473,7 +466,7 @@ static int ct_write(struct intel_guc_ct *ct, * @req: pointer to pending request * @status: placeholder for status * - * For each sent request, Guc shall send bac CT response message. + * For each sent request, GuC shall send back CT response message. * Our message handler will update status of tracked request once * response message with given fence is received. Wait here and * check for valid response status value. @@ -520,24 +513,35 @@ static inline bool ct_deadlocked(struct intel_guc_ct *ct) return ret; } -static inline bool h2g_has_room(struct intel_guc_ct_buffer *ctb, u32 len_dw) +static inline bool h2g_has_room(struct intel_guc_ct *ct, u32 len_dw) { - struct guc_ct_buffer_desc *desc = ctb->desc; - u32 head = READ_ONCE(desc->head); + struct intel_guc_ct_buffer *ctb = &ct->ctbs.send; + u32 head; u32 space; - space = CIRC_SPACE(desc->tail, head, ctb->size); + if (ctb->space >= len_dw) + return true; + + head = READ_ONCE(ctb->desc->head); + if (unlikely(head > ctb->size)) { + CT_ERROR(ct, "Corrupted descriptor head=%u tail=%u size=%u\n", + ctb->desc->head, ctb->desc->tail, ctb->size); + ctb->desc->status |= GUC_CTB_STATUS_OVERFLOW; + ctb->broken = true; + return false; + } + + space = CIRC_SPACE(ctb->tail, head, ctb->size); + ctb->space = space; 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 (unlikely(!h2g_has_room(ct, len_dw))) { if (ct->stall_time == KTIME_MAX) ct->stall_time = ktime_get(); @@ -606,10 +610,10 @@ static int ct_send(struct intel_guc_ct *ct, */ retry: spin_lock_irqsave(&ct->ctbs.send.lock, flags); - if (unlikely(!h2g_has_room(ctb, len + 1))) { + if (unlikely(!h2g_has_room(ct, len + 1))) { if (ct->stall_time == KTIME_MAX) ct->stall_time = ktime_get(); - spin_unlock_irqrestore(&ct->ctbs.send.lock, flags); + spin_unlock_irqrestore(&ctb->lock, flags); if (unlikely(ct_deadlocked(ct))) return -EIO; @@ -632,7 +636,7 @@ static int ct_send(struct intel_guc_ct *ct, err = ct_write(ct, action, len, fence, 0); - spin_unlock_irqrestore(&ct->ctbs.send.lock, flags); + spin_unlock_irqrestore(&ctb->lock, flags); if (unlikely(err)) goto unlink; @@ -720,7 +724,7 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) { struct intel_guc_ct_buffer *ctb = &ct->ctbs.recv; struct guc_ct_buffer_desc *desc = ctb->desc; - u32 head = desc->head; + u32 head = ctb->head; u32 tail = desc->tail; u32 size = ctb->size; u32 *cmds = ctb->cmds; @@ -735,12 +739,21 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) if (unlikely(desc->status)) goto corrupted; - if (unlikely((tail | head) >= size)) { +#ifdef CONFIG_DRM_I915_DEBUG_GUC + if (unlikely((desc->tail | desc->head) >= size)) { CT_ERROR(ct, "Invalid offsets head=%u tail=%u (size=%u)\n", head, tail, size); desc->status |= GUC_CTB_STATUS_OVERFLOW; goto corrupted; } +#else + if (unlikely((tail | ctb->head) >= size)) { + CT_ERROR(ct, "Invalid offsets head=%u tail=%u (size=%u)\n", + head, tail, size); + desc->status |= GUC_CTB_STATUS_OVERFLOW; + goto corrupted; + } +#endif /* tail == head condition indicates empty */ available = tail - head; @@ -790,6 +803,7 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) } CT_DEBUG(ct, "received %*ph\n", 4 * len, (*msg)->msg); + ctb->head = head; /* now update descriptor */ WRITE_ONCE(desc->head, head); 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 55ef7c52472f..9924335e2ee6 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h @@ -33,6 +33,9 @@ struct intel_guc; * @desc: pointer to the buffer descriptor * @cmds: pointer to the commands buffer * @size: size of the commands buffer in dwords + * @head: local shadow copy of head in dwords + * @tail: local shadow copy of tail in dwords + * @space: local shadow copy of space in dwords * @broken: flag to indicate if descriptor data is broken */ struct intel_guc_ct_buffer { @@ -40,6 +43,9 @@ struct intel_guc_ct_buffer { struct guc_ct_buffer_desc *desc; u32 *cmds; u32 size; + u32 tail; + u32 head; + u32 space; bool broken; };