Re: [Qemu-devel] [PATCH v2 1/3] hw/acpi-build: build SRAT memory affinity structures for DIMM devices

[Haozhong Zhang]

On 03/01/18 14:01 +0100, Igor Mammedov wrote:
> On Thu, 1 Mar 2018 19:56:51 +0800
> Haozhong Zhang <address@hidden> wrote:
> 
> > On 03/01/18 11:42 +0100, Igor Mammedov wrote:
> > > On Wed, 28 Feb 2018 12:02:58 +0800
> > > Haozhong Zhang <address@hidden> wrote:
> > >   
> > > > ACPI 6.2A Table 5-129 "SPA Range Structure" requires the proximity
> > > > domain of a NVDIMM SPA range must match with corresponding entry in
> > > > SRAT table.
> > > > 
> > > > The address ranges of vNVDIMM in QEMU are allocated from the
> > > > hot-pluggable address space, which is entirely covered by one SRAT
> > > > memory affinity structure. However, users can set the vNVDIMM
> > > > proximity domain in NFIT SPA range structure by the 'node' property of
> > > > '-device nvdimm' to a value different than the one in the above SRAT
> > > > memory affinity structure.
> > > > 
> > > > In order to solve such proximity domain mismatch, this patch builds
> > > > one SRAT memory affinity structure for each static-plugged DIMM device, 
> > > >  
> > > s/static-plugged/present at boot/
> > > since after hotplug and following reset SRAT will be recreated
> > > and include hotplugged DIMMs as well.  
> > 
> > Ah yes, I'll fix the message in the next version.
> > 
> > >   
> > > > including both PC-DIMM and NVDIMM, with the proximity domain specified
> > > > in '-device pc-dimm' or '-device nvdimm'.
> > > > 
> > > > The remaining hot-pluggable address space is covered by one or multiple
> > > > SRAT memory affinity structures with the proximity domain of the last
> > > > node as before.
> > > > 
> > > > Signed-off-by: Haozhong Zhang <address@hidden>
> > > > ---
> > > >  hw/i386/acpi-build.c     | 50 
> > > > ++++++++++++++++++++++++++++++++++++++++++++----
> > > >  hw/mem/pc-dimm.c         |  8 ++++++++
> > > >  include/hw/mem/pc-dimm.h | 10 ++++++++++
> > > >  3 files changed, 64 insertions(+), 4 deletions(-)
> > > > 
> > > > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > > > index deb440f286..a88de06d8f 100644
> > > > --- a/hw/i386/acpi-build.c
> > > > +++ b/hw/i386/acpi-build.c
> > > > @@ -2323,6 +2323,49 @@ build_tpm2(GArray *table_data, BIOSLinker 
> > > > *linker, GArray *tcpalog)
> > > >  #define HOLE_640K_START  (640 * 1024)
> > > >  #define HOLE_640K_END   (1024 * 1024)
> > > >  
> > > > +static void build_srat_hotpluggable_memory(GArray *table_data, 
> > > > uint64_t base,
> > > > +                                           uint64_t len, int 
> > > > default_node)
> > > > +{
> > > > +    GSList *dimms = pc_dimm_get_device_list();
> > > > +    GSList *ent = dimms;
> > > > +    PCDIMMDevice *dev;
> > > > +    Object *obj;
> > > > +    uint64_t end = base + len, addr, size;
> > > > +    int node;
> > > > +    AcpiSratMemoryAffinity *numamem;
> > > > +
> > > > +    while (base < end) {  
> > > It's just matter of taste but wouldn't 'for' loop be better here?
> > > One can see start, end and next step from the begging.  
> > 
> > will switch to a for loop
> > 
> > >   
> > > > +        numamem = acpi_data_push(table_data, sizeof *numamem);
> > > > +
> > > > +        if (!ent) {
> > > > +            build_srat_memory(numamem, base, end - base, default_node,
> > > > +                              MEM_AFFINITY_HOTPLUGGABLE | 
> > > > MEM_AFFINITY_ENABLED);
> > > > +            break;
> > > > +        }
> > > > +
> > > > +        dev = PC_DIMM(ent->data);
> > > > +        obj = OBJECT(dev);
> > > > +        addr = object_property_get_uint(obj, PC_DIMM_ADDR_PROP, NULL);
> > > > +        size = object_property_get_uint(obj, PC_DIMM_SIZE_PROP, NULL);
> > > > +        node = object_property_get_uint(obj, PC_DIMM_NODE_PROP, NULL);
> > > > +
> > > > +        if (base < addr) {
> > > > +            build_srat_memory(numamem, base, addr - base, default_node,
> > > > +                              MEM_AFFINITY_HOTPLUGGABLE | 
> > > > MEM_AFFINITY_ENABLED);
> > > > +            numamem = acpi_data_push(table_data, sizeof *numamem);
> > > > +        }
> > > > +        build_srat_memory(numamem, addr, size, node,
> > > > +                          MEM_AFFINITY_HOTPLUGGABLE | 
> > > > MEM_AFFINITY_ENABLED |  
> > > Is NVDIMM hotplug supported in QEMU?
> > > If not we might need make MEM_AFFINITY_HOTPLUGGABLE conditional too.  
> > 
> > Yes, it's supported.
> > 
> > >   
> > > > +                          (object_dynamic_cast(obj, TYPE_NVDIMM) ?
> > > > +                           MEM_AFFINITY_NON_VOLATILE : 0));  
> > > it might be cleaner without inline flags duplication
> > > 
> > >   flags = MEM_AFFINITY_ENABLED;
> > >   ...
> > >   if (!ent) {
> > >       flags |= MEM_AFFINITY_HOTPLUGGABLE
> > >   }
> > >   ...
> > >   if (PCDIMMDeviceInfo::hotpluggable) { // see ***
> > >       flags |= MEM_AFFINITY_HOTPLUGGABLE
> > >   }
> > >   ...
> > >   if (object_dynamic_cast(obj, TYPE_NVDIMM))
> > >       flags |= MEM_AFFINITY_NON_VOLATILE
> > >   }  
> > 
> > I'm fine for such changes, except ***
> > 
> > [..]
> > > > diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
> > > > index 6e74b61cb6..9fd901e87a 100644
> > > > --- a/hw/mem/pc-dimm.c
> > > > +++ b/hw/mem/pc-dimm.c
> > > > @@ -276,6 +276,14 @@ static int pc_dimm_built_list(Object *obj, void 
> > > > *opaque)
> > > >      return 0;
> > > >  }
> > > >  
> > > > +GSList *pc_dimm_get_device_list(void)
> > > > +{
> > > > +    GSList *list = NULL;
> > > > +
> > > > +    object_child_foreach(qdev_get_machine(), pc_dimm_built_list, 
> > > > &list);
> > > > +    return list;
> > > > +}  
> > > (***)
> > > see http://lists.gnu.org/archive/html/qemu-ppc/2018-02/msg00271.html
> > > You could do that in separate patch, so that it won't matter
> > > whose patch got merged first and it won't affect the rest of patches.  
> > 
> > Sure, I can separate this part, but I would still like to use a list
> > of PCDIMMDevice rather than a list of MemoryDeviceInfo. The latter
> > would need to be extended to include NVDIMM information (e.g., adding
> > a NVDIMMDeviceInfo to the union).
> You don't have to add NVDIMMDeviceInfo until there would be
> need to expose NVDIMM specific information.

Well, I need to know whether a memory device is NVDIMM in order to
decide whether the non-volatile flag is need in SRAT.

> 
> qmp_pc_dimm_device_list() API is sufficient in this case
> (modulo missing sorting).

sorting is not a big issue and can be easily added by using
pc_dimm_built_list in qmp_pc_dimm_device_list().

Haozhong

> 
> Suggestion has been made to keep number of public APIs that do
> almost the same at minimum.