Re: [Qemu-devel] [RFC PATCH 3/4] hw/arm/virt: Enable pc-dimm hotplug support

[Igor Mammedov <imammedo@redhat.com>]

On Fri, 1 Mar 2019 10:51:45 +0000
Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com> wrote:

> > -----Original Message-----
> > From: Qemu-devel
> > [mailto:qemu-devel-bounces+shameerali.kolothum.thodi=huawei.com@nongn
> > u.org] On Behalf Of Igor Mammedov
> > Sent: 01 March 2019 10:34
> > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> > Cc: peter.maydell@linaro.org; shannon.zhaosl@gmail.com;
> > qemu-devel@nongnu.org; Linuxarm <linuxarm@huawei.com>;
> > eric.auger@redhat.com; qemu-arm@nongnu.org; xuwei (O)
> > <xuwei5@huawei.com>
> > Subject: Re: [Qemu-devel] [RFC PATCH 3/4] hw/arm/virt: Enable pc-dimm
> > hotplug support
> > 
> > On Fri, 1 Mar 2019 11:26:35 +0100
> > Igor Mammedov <imammedo@redhat.com> wrote:
> >   
> > > On Fri, 1 Mar 2019 09:23:11 +0000
> > > Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>  
> > wrote:  
> > >  
> > > > > -----Original Message-----
> > > > > From: Igor Mammedov [mailto:imammedo@redhat.com]
> > > > > Sent: 01 March 2019 09:12
> > > > > To: Shameerali Kolothum Thodi  
> > <shameerali.kolothum.thodi@huawei.com>  
> > > > > Cc: eric.auger@redhat.com; shannon.zhaosl@gmail.com;
> > > > > peter.maydell@linaro.org; qemu-devel@nongnu.org;  
> > qemu-arm@nongnu.org;  
> > > > > Linuxarm <linuxarm@huawei.com>; xuwei (O) <xuwei5@huawei.com>
> > > > > Subject: Re: [Qemu-devel] [RFC PATCH 3/4] hw/arm/virt: Enable pc-dimm
> > > > > hotplug support
> > > > >
> > > > > On Mon, 28 Jan 2019 11:05:45 +0000
> > > > > Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> wrote:
> > > > >  
> > > > > > pc-dimm memory hotplug is enabled using GPIO(Pin 2) based ACPI
> > > > > > event. Hot removal functionality is not yet supported.
> > > > > >
> > > > > > Signed-off-by: Shameer Kolothum  
> > <shameerali.kolothum.thodi@huawei.com>  
> > > > > > ---
> > > > > >  hw/arm/virt.c | 57  
> > > > > +++++++++++++++++++++++++++++++++++++++++++++++++++++++--  
> > > > > >  1 file changed, 55 insertions(+), 2 deletions(-)
> > > > > >
> > > > > > diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> > > > > > index 884960d..cf64554 100644
> > > > > > --- a/hw/arm/virt.c
> > > > > > +++ b/hw/arm/virt.c
> > > > > > @@ -62,6 +62,7 @@
> > > > > >  #include "hw/mem/pc-dimm.h"
> > > > > >  #include "hw/mem/nvdimm.h"
> > > > > >  #include "hw/acpi/acpi.h"
> > > > > > +#include "hw/acpi/pc-hotplug.h"  
> > > > > it looks like x86 specific file, what is this here for?  
> > > >
> > > > Yes. That is for ACPI_MEMORY_HOTPLUG_BASE which is only used by x86
> > > > at the moment. I guess, it can be moved to hw/acpi/memory_hotplug.h ?  
> > > it's GPA and pc/q35 impl. specific so you should use it,  
> > s/should/should not/
> >   
> > > this address will always be board specific one.
> > > Makeup a virt specific one  
> 
> Ok. I was under the impression that the offsets can be reused as it is defined
> here docs/specs/acpi_mem_hotplug.txt(though that is GPE and pc/q35 acpi dev 
> specific). But agree, it doesn't make sense to make it generic.
Offsets defined by docs/specs/acpi_mem_hotplug.txt are meant to be reused
but IO port address (0xa00) where interface's address space starts is board specific.


> > > >  
> > > > > >
> > > > > >  #define DEFINE_VIRT_MACHINE_LATEST(major, minor, latest) \
> > > > > >      static void virt_##major##_##minor##_class_init(ObjectClass *oc,  
> > \  
> > > > > > @@ -1651,7 +1652,14 @@ static void machvirt_init(MachineState  
> > > > > *machine)  
> > > > > >          nvdimm_init_acpi_state(acpi_nvdimm_state, sysmem,
> > > > > >                                 vms->fw_cfg, OBJECT(vms));
> > > > > >      }
> > > > > > +    if (vms->acpi_memhp_state.is_enabled) {
> > > > > > +        MemHotplugState *state =  &vms->acpi_memhp_state;
> > > > > > +        hwaddr base;
> > > > > >
> > > > > > +        state->hw_reduced_acpi = true;
> > > > > > +        base = vms->memmap[VIRT_ACPI_IO].base +  
> > > > > ACPI_MEMORY_HOTPLUG_BASE;  
> > > well, this is confusing, why adding 2 base addresses?
> > > If vms->memmap[VIRT_ACPI_IO].base is already set than why not use it
> > > as is without adding an offset?  
> 
> Well, Eric's work on which this was based had one NVDIMM_ACPI_IO_BASE offset
> from what appears to be a generic VIRT_ACPI_IO region. Now I see that, it is
> renamed to VIRT_NVDIMM_ACPI_IO. Do we really need two separate regions?
I'm afraid we can't reuse MMIO regions as ther might be used at the same time
and do different things (we would have done this for x86 if it was possible)

As for naming try to find some consensus/coordinate it with Eric


> Thanks,
> Shameer
> 
> > >  
> > > > > > +        acpi_memory_hotplug_init(sysmem, OBJECT(vms), state,  
> > base);  
> > > > > > +    }
> > > > > >      vms->bootinfo.ram_size = machine->ram_size;
> > > > > >      vms->bootinfo.kernel_filename = machine->kernel_filename;
> > > > > >      vms->bootinfo.kernel_cmdline = machine->kernel_cmdline;  
> > > > > [...]  
> > >
> > >  
> >   
>