Re: [PATCH v6 6/7] hw/cxl/events: Add injection of DRAM events

[Ira Weiny <ira.weiny@intel.com>]

Jonathan Cameron wrote:
> On Fri, 19 May 2023 17:34:20 +0200
> Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
> 
> > Hi Jonathan,
> > 
> > On 19/5/23 16:30, Jonathan Cameron wrote:
> > > Defined in CXL r3.0 8.2.9.2.1.2 DRAM Event Record, this event
> > > provides information related to DRAM devices.
> > > 
> > > Example injection command in QMP:
> > > 
> > > { "execute": "cxl-inject-dram-event",
> > >      "arguments": {
> > >          "path": "/machine/peripheral/cxl-mem0",
> > >          "log": "informational",
> > >          "flags": 1,
> > >          "physaddr": 1000,
> > >          "descriptor": 3,
> > >          "type": 3,
> > >          "transaction-type": 192,
> > >          "channel": 3,
> > >          "rank": 17,
> > >          "nibble-mask": 37421234,
> > >          "bank-group": 7,
> > >          "bank": 11,
> > >          "row": 2,
> > >          "column": 77,
> > >          "correction-mask": [33, 44, 55,66]
> > >      }}
> > > 
> > > Reviewed-by: Ira Weiny <ira.weiny@intel.com>
> > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > > ---
> > >   hw/mem/cxl_type3.c          | 116 ++++++++++++++++++++++++++++++++++++
> > >   hw/mem/cxl_type3_stubs.c    |  13 ++++
> > >   include/hw/cxl/cxl_events.h |  23 +++++++
> > >   qapi/cxl.json               |  35 +++++++++++
> > >   4 files changed, 187 insertions(+)  
> > 
> > 
> > > diff --git a/qapi/cxl.json b/qapi/cxl.json
> > > index 7e1e6257ce..5e82097e76 100644
> > > --- a/qapi/cxl.json
> > > +++ b/qapi/cxl.json
> > > @@ -55,6 +55,41 @@
> > >               '*device': 'uint32', '*component-id': 'str'
> > >               }}
> > >   
> > > +##
> > > +# @cxl-inject-dram-event:
> > > +#
> > > +# Inject an event record for a DRAM Event (CXL r3.0 8.2.9.2.1.2)
> > > +# This event type is reported via one of the event logs specified via
> > > +# the log parameter.
> > > +#
> > > +# @path: CXL type 3 device canonical QOM path
> > > +# @log: Event Log to add the event to
> > > +# @flags: header flags
> > > +# @physaddr: Physical Address  
> > 
> > Could this be a clearer description?
> > 
> > "Physical Address (relative to @path device)"
> 
> Makes sense.
> 
> > 
> > > +# @descriptor: Descriptor
> > > +# @type: Type
> > > +# @transaction-type: Transaction Type
> > > +# @channel: Channel
> > > +# @rank: Rank
> > > +# @nibble-mask: Identify one or more nibbles that the error affects  
> > 
> > > +# @bank-group: Bank group
> > > +# @bank: Bank
> > > +# @row: Row
> > > +# @column: Column  
> > 
> > Why do we need bank/raw/col if we have physaddr?
> 
> Yes we need them. We don't know the device geometry / internal interleaving
> / address hashing applied to smooth out access patterns etc.
> 
> I really don't want to put that level of complexity into the command
> line for a device - so just left it to the test tools to squirt in
> something valid.
> 

I agree.  I don't think anyone is trying to emulate their exact memory
device internals.  However, it does not prevent them from doing so with
additional device types and/or qemu flags to get that behavior.

Ira