Re: [PATCH v4 13/25] ppc/xive: Introduce a xive_tctx_ipb_update() helper

["Cédric Le Goater" <clg@kaod.org>]

On 03/10/2019 04:11, David Gibson wrote:
> On Wed, Sep 18, 2019 at 06:06:33PM +0200, Cédric Le Goater wrote:
>> We will use it to resend missed interrupts when a vCPU context is
>> pushed a HW thread.
>>
>> Signed-off-by: Cédric Le Goater <clg@kaod.org>
>> ---
>>  include/hw/ppc/xive.h |  1 +
>>  hw/intc/xive.c        | 15 +++++++++++----
>>  2 files changed, 12 insertions(+), 4 deletions(-)
>>
>> diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h
>> index f35ff3b64791..a461753f5da5 100644
>> --- a/include/hw/ppc/xive.h
>> +++ b/include/hw/ppc/xive.h
>> @@ -467,6 +467,7 @@ uint64_t xive_tctx_tm_read(XivePresenter *xptr, XiveTCTX *tctx, hwaddr offset,
>>  
>>  void xive_tctx_pic_print_info(XiveTCTX *tctx, Monitor *mon);
>>  Object *xive_tctx_create(Object *cpu, XiveRouter *xrtr, Error **errp);
>> +void xive_tctx_ipb_update(XiveTCTX *tctx, uint8_t ring, uint8_t ipb);
>>  
>>  static inline uint32_t xive_nvt_cam_line(uint8_t nvt_blk, uint32_t nvt_idx)
>>  {
>> diff --git a/hw/intc/xive.c b/hw/intc/xive.c
>> index 68d3361d1c3f..5f7c37b091a7 100644
>> --- a/hw/intc/xive.c
>> +++ b/hw/intc/xive.c
>> @@ -135,6 +135,15 @@ static void xive_tctx_set_cppr(XiveTCTX *tctx, uint8_t ring, uint8_t cppr)
>>      xive_tctx_notify(tctx, ring);
>>  }
>>  
>> +void xive_tctx_ipb_update(XiveTCTX *tctx, uint8_t ring, uint8_t ipb)
>> +{
>> +    uint8_t *regs = &tctx->regs[ring];
>> +
>> +    regs[TM_IPB] |= ipb;
>> +    regs[TM_PIPR] = ipb_to_pipr(regs[TM_IPB]);
> 
> You're opencoding the existing ipb_update() here, but not eliminating
> it.  That doesn't seem like a good idea.
 It is in patch 15 when the IPB is correctly recorded in the NVT. 

I can move that part before patch 13 to make things clearer.


C. 

>> +    xive_tctx_notify(tctx, ring);
>> +}
>> +
>>  static inline uint32_t xive_tctx_word2(uint8_t *ring)
>>  {
>>      return *((uint32_t *) &ring[TM_WORD2]);
>> @@ -336,8 +345,7 @@ static void xive_tm_set_os_cppr(XivePresenter *xptr, XiveTCTX *tctx,
>>  static void xive_tm_set_os_pending(XivePresenter *xptr, XiveTCTX *tctx,
>>                                     hwaddr offset, uint64_t value, unsigned size)
>>  {
>> -    ipb_update(&tctx->regs[TM_QW1_OS], value & 0xff);
>> -    xive_tctx_notify(tctx, TM_QW1_OS);
>> +    xive_tctx_ipb_update(tctx, TM_QW1_OS, priority_to_ipb(value & 0xff));
>>  }
>>  
>>  static uint64_t xive_tm_pull_os_ctx(XivePresenter *xptr, XiveTCTX *tctx,
>> @@ -1382,8 +1390,7 @@ static bool xive_presenter_notify(uint8_t format,
>>  
>>      /* handle CPU exception delivery */
>>      if (count) {
>> -        ipb_update(&match.tctx->regs[match.ring], priority);
>> -        xive_tctx_notify(match.tctx, match.ring);
>> +        xive_tctx_ipb_update(match.tctx, match.ring, priority_to_ipb(priority));
>>      }
>>  
>>      return count;
>