Re: [PATCH v6 13/20] ppc/pnv: Clarify how the TIMA is accessed on a multichip system

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Nov 27, 2019 at 07:57:31AM +0100, Cédric Le Goater wrote:
> On 27/11/2019 06:23, David Gibson wrote:
> > On Mon, Nov 25, 2019 at 07:58:13AM +0100, Cédric Le Goater wrote:
> >> The TIMA region gives access to the thread interrupt context registers
> >> of a CPU. It is mapped at the same address on all chips and can be
> >> accessed by any CPU of the system. To identify the chip from which the
> >> access is being done, the PowerBUS uses a 'chip' field in the
> >> load/store messages. QEMU does not model these messages, instead, we
> >> extract the chip id from the CPU PIR and do a lookup at the machine
> >> level to fetch the targeted interrupt controller.
> >>
> >> Introduce pnv_get_chip() and pnv_xive_tm_get_xive() helpers to clarify
> >> this process in pnv_xive_get_tctx(). The latter will be removed in the
> >> subsequent patches but the same principle will be kept.
> >>
> >> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> >> ---
> >>  include/hw/ppc/pnv.h |  3 +++
> >>  hw/intc/pnv_xive.c   | 40 +++++++++++++++++++++++-----------------
> >>  hw/ppc/pnv.c         | 14 ++++++++++++++
> >>  3 files changed, 40 insertions(+), 17 deletions(-)
> >>
> >> diff --git a/include/hw/ppc/pnv.h b/include/hw/ppc/pnv.h
> >> index a58cfea3f2fd..3a7bc3c57e0d 100644
> >> --- a/include/hw/ppc/pnv.h
> >> +++ b/include/hw/ppc/pnv.h
> >> @@ -103,6 +103,7 @@ typedef struct Pnv9Chip {
> >>   * A SMT8 fused core is a pair of SMT4 cores.
> >>   */
> >>  #define PNV9_PIR2FUSEDCORE(pir) (((pir) >> 3) & 0xf)
> >> +#define PNV9_PIR2CHIP(pir)      (((pir) >> 8) & 0x7f)
> >>  
> >>  typedef struct PnvChipClass {
> >>      /*< private >*/
> >> @@ -197,6 +198,8 @@ static inline bool pnv_is_power9(PnvMachineState *pnv)
> >>      return pnv_chip_is_power9(pnv->chips[0]);
> >>  }
> >>  
> >> +PnvChip *pnv_get_chip(uint32_t chip_id);
> >> +
> >>  #define PNV_FDT_ADDR          0x01000000
> >>  #define PNV_TIMEBASE_FREQ     512000000ULL
> >>  
> >> diff --git a/hw/intc/pnv_xive.c b/hw/intc/pnv_xive.c
> >> index 95e9de312cd9..db9d9c11a8f4 100644
> >> --- a/hw/intc/pnv_xive.c
> >> +++ b/hw/intc/pnv_xive.c
> >> @@ -439,31 +439,37 @@ static int pnv_xive_match_nvt(XivePresenter *xptr, uint8_t format,
> >>      return count;
> >>  }
> >>  
> >> +/*
> >> + * The TIMA MMIO space is shared among the chips and to identify the
> >> + * chip from which the access is being done, we extract the chip id
> >> + * from the PIR.
> >> + */
> >> +static PnvXive *pnv_xive_tm_get_xive(PowerPCCPU *cpu)
> >> +{
> >> +    int pir = ppc_cpu_pir(cpu);
> >> +    PnvChip *chip;
> >> +    PnvXive *xive;
> >> +
> >> +    chip = pnv_get_chip(PNV9_PIR2CHIP(pir));
> >> +    assert(chip);
> >> +    xive = &PNV9_CHIP(chip)->xive;
> >> +
> >> +    if (!pnv_xive_is_cpu_enabled(xive, cpu)) {
> >> +        xive_error(xive, "IC: CPU %x is not enabled", pir);
> >> +    }
> >> +    return xive;
> >> +}
> >> +
> >>  static XiveTCTX *pnv_xive_get_tctx(XiveRouter *xrtr, CPUState *cs)
> >>  {
> >>      PowerPCCPU *cpu = POWERPC_CPU(cs);
> >> -    XiveTCTX *tctx = XIVE_TCTX(pnv_cpu_state(cpu)->intc);
> >> -    PnvXive *xive = NULL;
> >> -    CPUPPCState *env = &cpu->env;
> >> -    int pir = env->spr_cb[SPR_PIR].default_value;
> >> +    PnvXive *xive = pnv_xive_tm_get_xive(cpu);
> >>  
> >> -    /*
> >> -     * Perform an extra check on the HW thread enablement.
> >> -     *
> >> -     * The TIMA is shared among the chips and to identify the chip
> >> -     * from which the access is being done, we extract the chip id
> >> -     * from the PIR.
> >> -     */
> >> -    xive = pnv_xive_get_ic((pir >> 8) & 0xf);
> >>      if (!xive) {
> >>          return NULL;
> >>      }
> >>  
> >> -    if (!(xive->regs[PC_THREAD_EN_REG0 >> 3] & PPC_BIT(pir & 0x3f))) {
> > 
> > I'm not seeing any code which will replace this check on the thread
> > enabled register.  Is that really what you intend?
> 
> it is calling pnv_xive_tm_get_xive() which calls pnv_xive_is_cpu_enabled()
> which does the same check in better.

Ah, yes of course, thanks.

Applied to ppc-for-5.0.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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