Re: [Qemu-devel] [RFC PATCH v0 4/5] xics: Use arch_id instead of cpu_index in XICS code

[Igor Mammedov]

On Tue, 5 Jul 2016 14:59:20 +1000
David Gibson <address@hidden> wrote:

> On Tue, Jul 05, 2016 at 10:12:51AM +0530, Bharata B Rao wrote:
> > xics maintains an array of ICPState structures which is indexed
> > by cpu_index. Change this to index the ICPState array by arch_id
> > for pseries-2.7 onwards. This allows migration of guest to suceed
> > when there are holes in cpu_index range due to CPU hot removal.
> > 
> > Signed-off-by: Bharata B Rao <address@hidden>
> > ---
> >  hw/intc/xics.c       | 14 ++++++++++----
> >  hw/intc/xics_kvm.c   | 12 ++++++------
> >  hw/intc/xics_spapr.c | 33 ++++++++++++++++++++++++++-------
> >  3 files changed, 42 insertions(+), 17 deletions(-)
> > 
> > diff --git a/hw/intc/xics.c b/hw/intc/xics.c
> > index cd48f42..6b79a8e 100644
> > --- a/hw/intc/xics.c
> > +++ b/hw/intc/xics.c
> > @@ -50,9 +50,12 @@ int xics_get_cpu_index_by_dt_id(int cpu_dt_id)
> >  void xics_cpu_destroy(XICSState *xics, PowerPCCPU *cpu)
> >  {
> >      CPUState *cs = CPU(cpu);
> > -    ICPState *ss = &xics->ss[cs->cpu_index];
> > +    CPUClass *cc = CPU_GET_CLASS(cs);
> > +    int server = cs->prefer_arch_id_over_cpu_index ?
> > cc->get_arch_id(cs) :
> > +                 cs->cpu_index;
> 
> Requiring this conditional in all the callsites is pretty ugly.  I'd
> prefer to see a get_arch_id() helper that implements this fallback
> internally.
A cpu can look at prefer_arch_id_over_cpu_index and switch
behavior of get_arch_id() internally.

> 
> > +    ICPState *ss = &xics->ss[server];
> >  
> > -    assert(cs->cpu_index < xics->nr_servers);
> > +    assert(server < xics->nr_servers);
> >      assert(cs == ss->cs);
> >  
> >      ss->output = NULL;
> > @@ -63,10 +66,13 @@ void xics_cpu_setup(XICSState *xics, PowerPCCPU
> > *cpu) {
> >      CPUState *cs = CPU(cpu);
> >      CPUPPCState *env = &cpu->env;
> > -    ICPState *ss = &xics->ss[cs->cpu_index];
> > +    CPUClass *cc = CPU_GET_CLASS(cs);
> > +    int server = cs->prefer_arch_id_over_cpu_index ?
> > cc->get_arch_id(cs) :
> > +                 cs->cpu_index;
> > +    ICPState *ss = &xics->ss[server];
> >      XICSStateClass *info = XICS_COMMON_GET_CLASS(xics);
> >  
> > -    assert(cs->cpu_index < xics->nr_servers);
> > +    assert(server < xics->nr_servers);
> >  
> >      ss->cs = cs;
> >  
> > diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
> > index edbd62f..2610458 100644
> > --- a/hw/intc/xics_kvm.c
> > +++ b/hw/intc/xics_kvm.c
> > @@ -326,14 +326,14 @@ static const TypeInfo ics_kvm_info = {
> >   */
> >  static void xics_kvm_cpu_setup(XICSState *xics, PowerPCCPU *cpu)
> >  {
> > -    CPUState *cs;
> > -    ICPState *ss;
> > +    CPUState *cs = CPU(cpu);
> >      KVMXICSState *xicskvm = XICS_SPAPR_KVM(xics);
> > +    CPUClass *cc = CPU_GET_CLASS(cs);
> > +    int server = cs->prefer_arch_id_over_cpu_index ?
> > cc->get_arch_id(cs) :
> > +                 cs->cpu_index;
> > +    ICPState *ss = ss = &xics->ss[server];
> >  
> > -    cs = CPU(cpu);
> > -    ss = &xics->ss[cs->cpu_index];
> > -
> > -    assert(cs->cpu_index < xics->nr_servers);
> > +    assert(server < xics->nr_servers);
> >      if (xicskvm->kernel_xics_fd == -1) {
> >          abort();
> >      }
> > diff --git a/hw/intc/xics_spapr.c b/hw/intc/xics_spapr.c
> > index 618826d..fbc8205 100644
> > --- a/hw/intc/xics_spapr.c
> > +++ b/hw/intc/xics_spapr.c
> > @@ -43,16 +43,21 @@ static target_ulong h_cppr(PowerPCCPU *cpu,
> > sPAPRMachineState *spapr, target_ulong opcode, target_ulong *args)
> >  {
> >      CPUState *cs = CPU(cpu);
> > +    CPUClass *cc = CPU_GET_CLASS(cs);
> > +    int server = cs->prefer_arch_id_over_cpu_index ?
> > cc->get_arch_id(cs) :
> > +                 cs->cpu_index;
> >      target_ulong cppr = args[0];
> >  
> > -    icp_set_cppr(spapr->xics, cs->cpu_index, cppr);
> > +    icp_set_cppr(spapr->xics, server, cppr);
> >      return H_SUCCESS;
> >  }
> >  
> >  static target_ulong h_ipi(PowerPCCPU *cpu, sPAPRMachineState
> > *spapr, target_ulong opcode, target_ulong *args)
> >  {
> > -    target_ulong server = xics_get_cpu_index_by_dt_id(args[0]);
> > +    CPUState *cs = CPU(cpu);
> > +    target_ulong server = cs->prefer_arch_id_over_cpu_index ?
> > args[0] :
> > +                          xics_get_cpu_index_by_dt_id(args[0]);
> >      target_ulong mfrr = args[1];
> >  
> >      if (server >= spapr->xics->nr_servers) {
> > @@ -67,7 +72,10 @@ static target_ulong h_xirr(PowerPCCPU *cpu,
> > sPAPRMachineState *spapr, target_ulong opcode, target_ulong *args)
> >  {
> >      CPUState *cs = CPU(cpu);
> > -    uint32_t xirr = icp_accept(spapr->xics->ss + cs->cpu_index);
> > +    CPUClass *cc = CPU_GET_CLASS(cs);
> > +    int server = cs->prefer_arch_id_over_cpu_index ?
> > cc->get_arch_id(cs) :
> > +                 cs->cpu_index;
> > +    uint32_t xirr = icp_accept(spapr->xics->ss + server);
> >  
> >      args[0] = xirr;
> >      return H_SUCCESS;
> > @@ -77,7 +85,10 @@ static target_ulong h_xirr_x(PowerPCCPU *cpu,
> > sPAPRMachineState *spapr, target_ulong opcode, target_ulong *args)
> >  {
> >      CPUState *cs = CPU(cpu);
> > -    ICPState *ss = &spapr->xics->ss[cs->cpu_index];
> > +    CPUClass *cc = CPU_GET_CLASS(cs);
> > +    int server = cs->prefer_arch_id_over_cpu_index ?
> > cc->get_arch_id(cs) :
> > +                 cs->cpu_index;
> > +    ICPState *ss = &spapr->xics->ss[server];
> >      uint32_t xirr = icp_accept(ss);
> >  
> >      args[0] = xirr;
> > @@ -89,9 +100,12 @@ static target_ulong h_eoi(PowerPCCPU *cpu,
> > sPAPRMachineState *spapr, target_ulong opcode, target_ulong *args)
> >  {
> >      CPUState *cs = CPU(cpu);
> > +    CPUClass *cc = CPU_GET_CLASS(cs);
> > +    int server = cs->prefer_arch_id_over_cpu_index ?
> > cc->get_arch_id(cs) :
> > +                 cs->cpu_index;
> >      target_ulong xirr = args[0];
> >  
> > -    icp_eoi(spapr->xics, cs->cpu_index, xirr);
> > +    icp_eoi(spapr->xics, server, xirr);
> >      return H_SUCCESS;
> >  }
> >  
> > @@ -99,8 +113,11 @@ static target_ulong h_ipoll(PowerPCCPU *cpu,
> > sPAPRMachineState *spapr, target_ulong opcode, target_ulong *args)
> >  {
> >      CPUState *cs = CPU(cpu);
> > +    CPUClass *cc = CPU_GET_CLASS(cs);
> > +    int server = cs->prefer_arch_id_over_cpu_index ?
> > cc->get_arch_id(cs) :
> > +                 cs->cpu_index;
> >      uint32_t mfrr;
> > -    uint32_t xirr = icp_ipoll(spapr->xics->ss + cs->cpu_index,
> > &mfrr);
> > +    uint32_t xirr = icp_ipoll(spapr->xics->ss + server, &mfrr);
> >  
> >      args[0] = xirr;
> >      args[1] = mfrr;
> > @@ -113,6 +130,7 @@ static void rtas_set_xive(PowerPCCPU *cpu,
> > sPAPRMachineState *spapr, uint32_t nargs, target_ulong args,
> >                            uint32_t nret, target_ulong rets)
> >  {
> > +    CPUState *cs = CPU(cpu);
> >      ICSState *ics = spapr->xics->ics;
> >      uint32_t nr, server, priority;
> >  
> > @@ -122,7 +140,8 @@ static void rtas_set_xive(PowerPCCPU *cpu,
> > sPAPRMachineState *spapr, }
> >  
> >      nr = rtas_ld(args, 0);
> > -    server = xics_get_cpu_index_by_dt_id(rtas_ld(args, 1));
> > +    server = cs->prefer_arch_id_over_cpu_index ? rtas_ld(args, 1) :
> > +             xics_get_cpu_index_by_dt_id(rtas_ld(args, 1));
> >      priority = rtas_ld(args, 2);
> >  
> >      if (!ics_valid_irq(ics, nr) || (server >=
> > ics->xics->nr_servers)
>