diff mbox series

[2/2] hw/cxl/cxl_event: Fix interrupt triggering for dynamic capacity events grouped via More flag

Message ID 20240827164304.88876-3-nifan.cxl@gmail.com (mailing list archive)
State New, archived
Headers show
Series QEMU DCD emulation support fix | expand

Commit Message

Fan Ni Aug. 27, 2024, 4:40 p.m. UTC 
From: Fan Ni <fan.ni@samsung.com>

When inserting multiple dynamic capacity event records grouped via More flag,
we should only trigger interrupt after the last record is inserted into the
event log. Achieving the goal by letting cxl_event_insert return true only
for the insertion of the last dynamic capacity event record in the sequence.

Signed-off-by: Fan Ni <fan.ni@samsung.com>
---
 hw/cxl/cxl-events.c         | 8 ++++++++
 include/hw/cxl/cxl_events.h | 1 +
 2 files changed, 9 insertions(+)

Comments

Jonathan Cameron Aug. 28, 2024, 11:39 a.m. UTC | #1 
On Tue, 27 Aug 2024 09:40:05 -0700
nifan.cxl@gmail.com wrote:

> From: Fan Ni <fan.ni@samsung.com>
> 
> When inserting multiple dynamic capacity event records grouped via More flag,
> we should only trigger interrupt after the last record is inserted into the
> event log. Achieving the goal by letting cxl_event_insert return true only
> for the insertion of the last dynamic capacity event record in the sequence.

I'm not sure this one is accurate.  We might well have a slow
system provisioning capacity one extent at time (and interrupting).

The event buffer might also not be large enough to hold all records so
the device might 'wait' before figuring out the next extent for there
to be somewhere to put the record.

Overall I think we can interrupt on each one and it should 'work'
as should interrupt only once there are lots of them or
every (n).

Interrupt only fires on a 0 to >= 1 transition anyway, not
on repeats after that unless the log has been cleared.
It's up to OS to keep clearing records until it at least
momentarily hits 0 if it wants to get any more interrupts.

Jonathan


> 
> Signed-off-by: Fan Ni <fan.ni@samsung.com>
> ---
>  hw/cxl/cxl-events.c         | 8 ++++++++
>  include/hw/cxl/cxl_events.h | 1 +
>  2 files changed, 9 insertions(+)
> 
> diff --git a/hw/cxl/cxl-events.c b/hw/cxl/cxl-events.c
> index 12dee2e467..90536c0e68 100644
> --- a/hw/cxl/cxl-events.c
> +++ b/hw/cxl/cxl-events.c
> @@ -135,6 +135,14 @@ bool cxl_event_insert(CXLDeviceState *cxlds, CXLEventLogType log_type,
>      QSIMPLEQ_INSERT_TAIL(&log->events, entry, node);
>      cxl_event_set_status(cxlds, log_type, true);
>  
> +    /*
> +     * For dynamic capacity event records grouped via More flag,
> +     * Only raise interrupt after inserting the last record in the log.
> +     */
> +    if (log_type == CXL_EVENT_TYPE_DYNAMIC_CAP) {
> +        CXLEventDynamicCapacity *dCap = (CXLEventDynamicCapacity *)event;
> +        return (dCap->flags & MORE_FLAG) ? false : true;
> +    }
>      /* Count went from 0 to 1 */
>      return cxl_event_count(log) == 1;

If there are multiple this will fail I think as cxl_event_count(log) will go from 0
to X not 1.

>  }
> diff --git a/include/hw/cxl/cxl_events.h b/include/hw/cxl/cxl_events.h
> index 38cadaa0f3..b0e5cc89c0 100644
> --- a/include/hw/cxl/cxl_events.h
> +++ b/include/hw/cxl/cxl_events.h
> @@ -170,6 +170,7 @@ typedef struct CXLEventMemoryModule {
>   * CXL r3.1 section Table 8-50: Dynamic Capacity Event Record
>   * All fields little endian.
>   */
> +#define MORE_FLAG BIT_MASK(0)
>  typedef struct CXLEventDynamicCapacity {
>      CXLEventRecordHdr hdr;
>      uint8_t type;
Ira Weiny Sept. 4, 2024, 4:37 p.m. UTC | #2 
Jonathan Cameron wrote:
> On Tue, 27 Aug 2024 09:40:05 -0700
> nifan.cxl@gmail.com wrote:
> 
> > From: Fan Ni <fan.ni@samsung.com>
> > 
> > When inserting multiple dynamic capacity event records grouped via More flag,
> > we should only trigger interrupt after the last record is inserted into the
> > event log. Achieving the goal by letting cxl_event_insert return true only
> > for the insertion of the last dynamic capacity event record in the sequence.
> 
> I'm not sure this one is accurate.  We might well have a slow
> system provisioning capacity one extent at time (and interrupting).
> 
> The event buffer might also not be large enough to hold all records so
> the device might 'wait' before figuring out the next extent for there
> to be somewhere to put the record.
> 
> Overall I think we can interrupt on each one and it should 'work'
> as should interrupt only once there are lots of them or
> every (n).

Indeed I think it should work.  But you won't see any extents as they will
be pending in the memdev.

Did this fail in some way?  I'm sorry I did not try and use qemu to test
the more bit.  Rather I used cxl_test for that.

Ira

> 
> Interrupt only fires on a 0 to >= 1 transition anyway, not
> on repeats after that unless the log has been cleared.
> It's up to OS to keep clearing records until it at least
> momentarily hits 0 if it wants to get any more interrupts.
> 
> Jonathan
> 
> 
> > 
> > Signed-off-by: Fan Ni <fan.ni@samsung.com>
> > ---
> >  hw/cxl/cxl-events.c         | 8 ++++++++
> >  include/hw/cxl/cxl_events.h | 1 +
> >  2 files changed, 9 insertions(+)
> > 
> > diff --git a/hw/cxl/cxl-events.c b/hw/cxl/cxl-events.c
> > index 12dee2e467..90536c0e68 100644
> > --- a/hw/cxl/cxl-events.c
> > +++ b/hw/cxl/cxl-events.c
> > @@ -135,6 +135,14 @@ bool cxl_event_insert(CXLDeviceState *cxlds, CXLEventLogType log_type,
> >      QSIMPLEQ_INSERT_TAIL(&log->events, entry, node);
> >      cxl_event_set_status(cxlds, log_type, true);
> >  
> > +    /*
> > +     * For dynamic capacity event records grouped via More flag,
> > +     * Only raise interrupt after inserting the last record in the log.
> > +     */
> > +    if (log_type == CXL_EVENT_TYPE_DYNAMIC_CAP) {
> > +        CXLEventDynamicCapacity *dCap = (CXLEventDynamicCapacity *)event;
> > +        return (dCap->flags & MORE_FLAG) ? false : true;
> > +    }
> >      /* Count went from 0 to 1 */
> >      return cxl_event_count(log) == 1;
> 
> If there are multiple this will fail I think as cxl_event_count(log) will go from 0
> to X not 1.
> 
> >  }
> > diff --git a/include/hw/cxl/cxl_events.h b/include/hw/cxl/cxl_events.h
> > index 38cadaa0f3..b0e5cc89c0 100644
> > --- a/include/hw/cxl/cxl_events.h
> > +++ b/include/hw/cxl/cxl_events.h
> > @@ -170,6 +170,7 @@ typedef struct CXLEventMemoryModule {
> >   * CXL r3.1 section Table 8-50: Dynamic Capacity Event Record
> >   * All fields little endian.
> >   */
> > +#define MORE_FLAG BIT_MASK(0)
> >  typedef struct CXLEventDynamicCapacity {
> >      CXLEventRecordHdr hdr;
> >      uint8_t type;
>
Fan Ni Sept. 4, 2024, 4:50 p.m. UTC | #3 
On Wed, Sep 04, 2024 at 11:37:33AM -0500, Ira Weiny wrote:
> Jonathan Cameron wrote:
> > On Tue, 27 Aug 2024 09:40:05 -0700
> > nifan.cxl@gmail.com wrote:
> > 
> > > From: Fan Ni <fan.ni@samsung.com>
> > > 
> > > When inserting multiple dynamic capacity event records grouped via More flag,
> > > we should only trigger interrupt after the last record is inserted into the
> > > event log. Achieving the goal by letting cxl_event_insert return true only
> > > for the insertion of the last dynamic capacity event record in the sequence.
> > 
> > I'm not sure this one is accurate.  We might well have a slow
> > system provisioning capacity one extent at time (and interrupting).
> > 
> > The event buffer might also not be large enough to hold all records so
> > the device might 'wait' before figuring out the next extent for there
> > to be somewhere to put the record.
> > 
> > Overall I think we can interrupt on each one and it should 'work'
> > as should interrupt only once there are lots of them or
> > every (n).
> 
> Indeed I think it should work.  But you won't see any extents as they will
> be pending in the memdev.
> 
> Did this fail in some way?  I'm sorry I did not try and use qemu to test
> the more bit.  Rather I used cxl_test for that.
> 
> Ira

It works with or without this fix in my test. Until the last extent is
notified to the OS, the extents will be pending as you mentioned. 

Fan

> 
> > 
> > Interrupt only fires on a 0 to >= 1 transition anyway, not
> > on repeats after that unless the log has been cleared.
> > It's up to OS to keep clearing records until it at least
> > momentarily hits 0 if it wants to get any more interrupts.
> > 
> > Jonathan
> > 
> > 
> > > 
> > > Signed-off-by: Fan Ni <fan.ni@samsung.com>
> > > ---
> > >  hw/cxl/cxl-events.c         | 8 ++++++++
> > >  include/hw/cxl/cxl_events.h | 1 +
> > >  2 files changed, 9 insertions(+)
> > > 
> > > diff --git a/hw/cxl/cxl-events.c b/hw/cxl/cxl-events.c
> > > index 12dee2e467..90536c0e68 100644
> > > --- a/hw/cxl/cxl-events.c
> > > +++ b/hw/cxl/cxl-events.c
> > > @@ -135,6 +135,14 @@ bool cxl_event_insert(CXLDeviceState *cxlds, CXLEventLogType log_type,
> > >      QSIMPLEQ_INSERT_TAIL(&log->events, entry, node);
> > >      cxl_event_set_status(cxlds, log_type, true);
> > >  
> > > +    /*
> > > +     * For dynamic capacity event records grouped via More flag,
> > > +     * Only raise interrupt after inserting the last record in the log.
> > > +     */
> > > +    if (log_type == CXL_EVENT_TYPE_DYNAMIC_CAP) {
> > > +        CXLEventDynamicCapacity *dCap = (CXLEventDynamicCapacity *)event;
> > > +        return (dCap->flags & MORE_FLAG) ? false : true;
> > > +    }
> > >      /* Count went from 0 to 1 */
> > >      return cxl_event_count(log) == 1;
> > 
> > If there are multiple this will fail I think as cxl_event_count(log) will go from 0
> > to X not 1.
> > 
> > >  }
> > > diff --git a/include/hw/cxl/cxl_events.h b/include/hw/cxl/cxl_events.h
> > > index 38cadaa0f3..b0e5cc89c0 100644
> > > --- a/include/hw/cxl/cxl_events.h
> > > +++ b/include/hw/cxl/cxl_events.h
> > > @@ -170,6 +170,7 @@ typedef struct CXLEventMemoryModule {
> > >   * CXL r3.1 section Table 8-50: Dynamic Capacity Event Record
> > >   * All fields little endian.
> > >   */
> > > +#define MORE_FLAG BIT_MASK(0)
> > >  typedef struct CXLEventDynamicCapacity {
> > >      CXLEventRecordHdr hdr;
> > >      uint8_t type;
> > 
> 
>
diff mbox series

Patch

diff --git a/hw/cxl/cxl-events.c b/hw/cxl/cxl-events.c
index 12dee2e467..90536c0e68 100644
--- a/hw/cxl/cxl-events.c
+++ b/hw/cxl/cxl-events.c
@@ -135,6 +135,14 @@  bool cxl_event_insert(CXLDeviceState *cxlds, CXLEventLogType log_type,
     QSIMPLEQ_INSERT_TAIL(&log->events, entry, node);
     cxl_event_set_status(cxlds, log_type, true);
 
+    /*
+     * For dynamic capacity event records grouped via More flag,
+     * Only raise interrupt after inserting the last record in the log.
+     */
+    if (log_type == CXL_EVENT_TYPE_DYNAMIC_CAP) {
+        CXLEventDynamicCapacity *dCap = (CXLEventDynamicCapacity *)event;
+        return (dCap->flags & MORE_FLAG) ? false : true;
+    }
     /* Count went from 0 to 1 */
     return cxl_event_count(log) == 1;
 }
diff --git a/include/hw/cxl/cxl_events.h b/include/hw/cxl/cxl_events.h
index 38cadaa0f3..b0e5cc89c0 100644
--- a/include/hw/cxl/cxl_events.h
+++ b/include/hw/cxl/cxl_events.h
@@ -170,6 +170,7 @@  typedef struct CXLEventMemoryModule {
  * CXL r3.1 section Table 8-50: Dynamic Capacity Event Record
  * All fields little endian.
  */
+#define MORE_FLAG BIT_MASK(0)
 typedef struct CXLEventDynamicCapacity {
     CXLEventRecordHdr hdr;
     uint8_t type;