Re: [PATCH v8 4/7] spapr_numa.c: rename numa_assoc_array to FORM1_assoc_array

[Daniel Henrique Barboza]

On 9/20/21 06:21, Greg Kurz wrote:
> On Fri, 17 Sep 2021 18:27:59 -0300
> Daniel Henrique Barboza <danielhb413@gmail.com> wrote:
>
> > Introducing a new NUMA affinity, FORM2, requires a new mechanism to
> > switch between affinity modes after CAS. Also, we want FORM2 data
> > structures and functions to be completely separated from the existing
> > FORM1 code, allowing us to avoid adding new code that inherits the
> > existing complexity of FORM1.
> >
> > The idea of switching values used by the write_dt() functions in
> > spapr_numa.c was already introduced in the previous patch, and
> > the same approach will be used when dealing with the FORM1 and FORM2
> > arrays.
> >
> > We can accomplish that by that by renaming the existing numa_assoc_array
> > to FORM1_assoc_array, which now is used exclusively to handle FORM1 affinity
> > data. A new helper get_associativity() is then introduced to be used by the
> > write_dt() functions to retrieve the current ibm,associativity array of
> > a given node, after considering affinity selection that might have been
> > done during CAS. All code that was using numa_assoc_array now needs to
> > retrieve the array by calling this function.
> >
> > This will allow for an easier plug of FORM2 data later on.
> >
> > Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> > ---
>
> This looks good. Just one suggestion, see below.
>
> >   hw/ppc/spapr_hcall.c   |  1 +
> >   hw/ppc/spapr_numa.c    | 38 +++++++++++++++++++++++++-------------
> >   include/hw/ppc/spapr.h |  2 +-
> >   3 files changed, 27 insertions(+), 14 deletions(-)
> >
> > diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> > index 0e9a5b2e40..9056644890 100644
> > --- a/hw/ppc/spapr_hcall.c
> > +++ b/hw/ppc/spapr_hcall.c
> > @@ -17,6 +17,7 @@
> >   #include "kvm_ppc.h"
> >   #include "hw/ppc/fdt.h"
> >   #include "hw/ppc/spapr_ovec.h"
> > +#include "hw/ppc/spapr_numa.h"
> >   #include "mmu-book3s-v3.h"
> >   #include "hw/mem/memory-device.h"
> >   
> > diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c
> > index 08e2d6aed8..7339d00d20 100644
> > --- a/hw/ppc/spapr_numa.c
> > +++ b/hw/ppc/spapr_numa.c
> > @@ -46,6 +46,15 @@ static int get_vcpu_assoc_size(SpaprMachineState *spapr)
> >       return get_numa_assoc_size(spapr) + 1;
> >   }
> >   
> > +/*
> > + * Retrieves the ibm,associativity array of NUMA node 'node_id'
> > + * for the current NUMA affinity.
> > + */
> > +static uint32_t *get_associativity(SpaprMachineState *spapr, int node_id)
> > +{
> > +    return spapr->FORM1_assoc_array[node_id];
> > +}
>
> All users of this helper only need to read the content of the
> associativity array. And since these arrays are static, the
> returned pointer should certainly not be passed to g_free()
> for example. This wouldn't be detected by compilers though,
> unless you have the helper to return a pointer to const
> data. So I suggest you just do that for extra safety.

Good point. I'll be more vigilant about the use of const pointers in these
cases. The extra safety is always welcome.


Daniel

> > +
> >   static bool spapr_numa_is_symmetrical(MachineState *ms)
> >   {
> >       int src, dst;
> > @@ -124,7 +133,7 @@ static void 
> > spapr_numa_define_FORM1_domains(SpaprMachineState *spapr)
> >        */
> >       for (i = 1; i < nb_numa_nodes; i++) {
> >           for (j = 1; j < FORM1_DIST_REF_POINTS; j++) {
> > -            spapr->numa_assoc_array[i][j] = cpu_to_be32(i);
> > +            spapr->FORM1_assoc_array[i][j] = cpu_to_be32(i);
> >           }
> >       }
> >   
> > @@ -176,8 +185,8 @@ static void spapr_numa_define_FORM1_domains(SpaprMachineState *spapr)
> >                * and going up to 0x1.
> >                */
> >               for (i = n_level; i > 0; i--) {
> > -                assoc_src = spapr->numa_assoc_array[src][i];
> > -                spapr->numa_assoc_array[dst][i] = assoc_src;
> > +                assoc_src = spapr->FORM1_assoc_array[src][i];
> > +                spapr->FORM1_assoc_array[dst][i] = assoc_src;
> >               }
> >           }
> >       }
> > @@ -204,8 +213,8 @@ static void 
> > spapr_numa_FORM1_affinity_init(SpaprMachineState *spapr,
> >        * 'i' will be a valid node_id set by the user.
> >        */
> >       for (i = 0; i < nb_numa_nodes; i++) {
> > -        spapr->numa_assoc_array[i][0] = cpu_to_be32(FORM1_DIST_REF_POINTS);
> > -        spapr->numa_assoc_array[i][FORM1_DIST_REF_POINTS] = cpu_to_be32(i);
> > +        spapr->FORM1_assoc_array[i][0] = cpu_to_be32(FORM1_DIST_REF_POINTS);
> > +        spapr->FORM1_assoc_array[i][FORM1_DIST_REF_POINTS] = cpu_to_be32(i);
> >       }
> >   
> >       /*
> > @@ -219,15 +228,15 @@ static void 
> > spapr_numa_FORM1_affinity_init(SpaprMachineState *spapr,
> >       max_nodes_with_gpus = nb_numa_nodes + NVGPU_MAX_NUM;
> >   
> >       for (i = nb_numa_nodes; i < max_nodes_with_gpus; i++) {
> > -        spapr->numa_assoc_array[i][0] = cpu_to_be32(FORM1_DIST_REF_POINTS);
> > +        spapr->FORM1_assoc_array[i][0] = cpu_to_be32(FORM1_DIST_REF_POINTS);
> >   
> >           for (j = 1; j < FORM1_DIST_REF_POINTS; j++) {
> >               uint32_t gpu_assoc = smc->pre_5_1_assoc_refpoints ?
> >                                    SPAPR_GPU_NUMA_ID : cpu_to_be32(i);
> > -            spapr->numa_assoc_array[i][j] = gpu_assoc;
> > +            spapr->FORM1_assoc_array[i][j] = gpu_assoc;
> >           }
> >   
> > -        spapr->numa_assoc_array[i][FORM1_DIST_REF_POINTS] = cpu_to_be32(i);
> > +        spapr->FORM1_assoc_array[i][FORM1_DIST_REF_POINTS] = cpu_to_be32(i);
> >       }
> >   
> >       /*
> > @@ -259,8 +268,10 @@ void spapr_numa_associativity_init(SpaprMachineState 
> > *spapr,
> >   void spapr_numa_write_associativity_dt(SpaprMachineState *spapr, void *fdt,
> >                                          int offset, int nodeid)
> >   {
> > +    uint32_t *associativity = get_associativity(spapr, nodeid);
> > +
> >       _FDT((fdt_setprop(fdt, offset, "ibm,associativity",
> > -                      spapr->numa_assoc_array[nodeid],
> > +                      associativity,
> >                         get_numa_assoc_size(spapr) * sizeof(uint32_t))));
> >   }
> >   
> > @@ -270,6 +281,7 @@ static uint32_t *spapr_numa_get_vcpu_assoc(SpaprMachineState *spapr,
> >       int max_distance_ref_points = get_max_dist_ref_points(spapr);
> >       int vcpu_assoc_size = get_vcpu_assoc_size(spapr);
> >       uint32_t *vcpu_assoc = g_new(uint32_t, vcpu_assoc_size);
> > +    uint32_t *associativity = get_associativity(spapr, cpu->node_id);
> >       int index = spapr_get_vcpu_id(cpu);
> >   
> >       /*
> > @@ -280,7 +292,7 @@ static uint32_t 
> > *spapr_numa_get_vcpu_assoc(SpaprMachineState *spapr,
> >        */
> >       vcpu_assoc[0] = cpu_to_be32(max_distance_ref_points + 1);
> >       vcpu_assoc[vcpu_assoc_size - 1] = cpu_to_be32(index);
> > -    memcpy(vcpu_assoc + 1, spapr->numa_assoc_array[cpu->node_id] + 1,
> > +    memcpy(vcpu_assoc + 1, associativity + 1,
> >              (vcpu_assoc_size - 2) * sizeof(uint32_t));
> >   
> >       return vcpu_assoc;
> > @@ -319,10 +331,10 @@ int 
> > spapr_numa_write_assoc_lookup_arrays(SpaprMachineState *spapr, void *fdt,
> >       cur_index += 2;
> >       for (i = 0; i < nr_nodes; i++) {
> >           /*
> > -         * For the lookup-array we use the ibm,associativity array,
> > -         * from numa_assoc_array. without the first element (size).
> > +         * For the lookup-array we use the ibm,associativity array of the
> > +         * current NUMA affinity, without the first element (size).
> >            */
> > -        uint32_t *associativity = spapr->numa_assoc_array[i];
> > +        uint32_t *associativity = get_associativity(spapr, i);
> >           memcpy(cur_index, ++associativity,
> >                  sizeof(uint32_t) * max_distance_ref_points);
> >           cur_index += max_distance_ref_points;
> > diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> > index 814e087e98..6b3dfc5dc2 100644
> > --- a/include/hw/ppc/spapr.h
> > +++ b/include/hw/ppc/spapr.h
> > @@ -249,7 +249,7 @@ struct SpaprMachineState {
> >       unsigned gpu_numa_id;
> >       SpaprTpmProxy *tpm_proxy;
> >   
> > -    uint32_t numa_assoc_array[NUMA_NODES_MAX_NUM][FORM1_NUMA_ASSOC_SIZE];
> > +    uint32_t FORM1_assoc_array[NUMA_NODES_MAX_NUM][FORM1_NUMA_ASSOC_SIZE];
> >   
> >       Error *fwnmi_migration_blocker;
> >   };