Re: [Qemu-devel] [PATCH qemu v2] hmp: Print if memory section is registered with an accelerator

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Hi Alexey,

On 12/14/18 3:58 AM, Alexey Kardashevskiy wrote:
> This adds an accelerator name to the "into mtree -f" to tell the user if
> a particular memory section is registered with the accelerator;
> the primary user for this is KVM and such information is useful
> for debugging purposes.
> 
> This adds a has_memory() callback to the accelerator class allowing any
> accelerator to have a label in that memory tree dump.
> 
> Since memory sections are passed to memory listeners and get registered
> in accelerators (rather than memory regions), this only prints new labels
> for flatviews attached to the system address space.
> 
> An example:
>  Root memory region: system
>   0000000000000000-0000002fffffffff (prio 0, ram): /objects/mem0 kvm
>   0000003000000000-0000005fffffffff (prio 0, ram): /objects/mem1 kvm
>   0000200000000020-000020000000003f (prio 1, i/o): virtio-pci
>   0000200080000000-000020008000003f (prio 0, i/o): capabilities
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
> 
> This supercedes "[PATCH qemu] hmp: Print if memory section is registered in KVM"
> 
> ---
> Changes:
> v2:
> * added an accelerator callback instead of hardcoding it to kvm only
> ---
>  include/sysemu/accel.h |  2 ++
>  accel/kvm/kvm-all.c    | 10 ++++++++++
>  memory.c               | 22 ++++++++++++++++++++++
>  3 files changed, 34 insertions(+)
> 
> diff --git a/include/sysemu/accel.h b/include/sysemu/accel.h
> index 637358f..30b456d 100644
> --- a/include/sysemu/accel.h
> +++ b/include/sysemu/accel.h
> @@ -25,6 +25,7 @@
>  
>  #include "qom/object.h"
>  #include "hw/qdev-properties.h"
> +#include "exec/hwaddr.h"
>  
>  typedef struct AccelState {
>      /*< private >*/
> @@ -41,6 +42,7 @@ typedef struct AccelClass {
>      int (*available)(void);
>      int (*init_machine)(MachineState *ms);
>      void (*setup_post)(MachineState *ms, AccelState *accel);
> +    bool (*has_memory)(MachineState *ms, hwaddr start_addr, hwaddr size);
>      bool *allowed;
>      /*
>       * Array of global properties that would be applied when specific
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index 4880a05..634f386 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -2589,11 +2589,21 @@ int kvm_get_one_reg(CPUState *cs, uint64_t id, void *target)
>      return r;
>  }
>  
> +static bool kvm_accel_has_memory(MachineState *ms, hwaddr start_addr,
> +                                 hwaddr size)
> +{
> +    KVMState *kvm = KVM_STATE(ms->accelerator);
> +    KVMMemoryListener *kml = &kvm->memory_listener;
> +
> +    return NULL != kvm_lookup_matching_slot(kml, start_addr, size);
> +}
> +
>  static void kvm_accel_class_init(ObjectClass *oc, void *data)
>  {
>      AccelClass *ac = ACCEL_CLASS(oc);
>      ac->name = "KVM";
>      ac->init_machine = kvm_init;
> +    ac->has_memory = kvm_accel_has_memory;
>      ac->allowed = &kvm_allowed;
>  }
>  
> diff --git a/memory.c b/memory.c
> index d14c6de..61e758a 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -29,7 +29,9 @@
>  #include "exec/ram_addr.h"
>  #include "sysemu/kvm.h"
>  #include "sysemu/sysemu.h"
> +#include "sysemu/accel.h"
>  #include "hw/qdev-properties.h"
> +#include "hw/boards.h"
>  #include "migration/vmstate.h"
>  
>  //#define DEBUG_UNASSIGNED
> @@ -2924,6 +2926,8 @@ struct FlatViewInfo {
>      int counter;
>      bool dispatch_tree;
>      bool owner;
> +    AccelClass *ac;
> +    const char *ac_name;
>  };
>  
>  static void mtree_print_flatview(gpointer key, gpointer value,
> @@ -2939,6 +2943,7 @@ static void mtree_print_flatview(gpointer key, gpointer value,
>      int n = view->nr;
>      int i;
>      AddressSpace *as;
> +    bool system_as = false;
>  
>      p(f, "FlatView #%d\n", fvi->counter);
>      ++fvi->counter;
> @@ -2950,6 +2955,9 @@ static void mtree_print_flatview(gpointer key, gpointer value,
>              p(f, ", alias %s", memory_region_name(as->root->alias));
>          }
>          p(f, "\n");
> +        if (as == &address_space_memory) {
> +            system_as = true;
> +        }
>      }
>  
>      p(f, " Root memory region: %s\n",
> @@ -2985,6 +2993,13 @@ static void mtree_print_flatview(gpointer key, gpointer value,
>          if (fvi->owner) {
>              mtree_print_mr_owner(p, f, mr);
>          }
> +
> +        if (system_as && fvi->ac &&
> +            fvi->ac->has_memory(current_machine,
> +                                int128_get64(range->addr.start),
> +                                MR_SIZE(range->addr.size) + 1)) {
> +            p(f, " %s", fvi->ac_name);

Why not simply display fvi->ac->name?
You could avoid to add the ac_name field.

> +        }
>          p(f, "\n");
>          range++;
>      }
> @@ -3028,6 +3043,13 @@ void mtree_info(fprintf_function mon_printf, void *f, bool flatview,
>          };
>          GArray *fv_address_spaces;
>          GHashTable *views = g_hash_table_new(g_direct_hash, g_direct_equal);
> +        AccelClass *ac = ACCEL_GET_CLASS(current_machine->accelerator);
> +
> +        if (ac->has_memory) {
> +            fvi.ac = ac;
> +            fvi.ac_name = current_machine->accel ? current_machine->accel :
> +                object_class_get_name(OBJECT_CLASS(ac));
> +        }
>  
>          /* Gather all FVs in one table */
>          QTAILQ_FOREACH(as, &address_spaces, address_spaces_link) {
>