Re: [PATCH v7 09/10] hw/arm/virt: add ITS support in virt GIC

[shashi . mallela]

On Fri, 2021-08-06 at 13:09 +0200, Igor Mammedov wrote:
> On Thu,  5 Aug 2021 18:30:01 -0400
> Shashi Mallela <shashi.mallela@linaro.org> wrote:
> 
> > Included creation of ITS as part of virt platform GIC
> > initialization. This Emulated ITS model now co-exists with kvm
> > ITS and is enabled in absence of kvm irq kernel support in a
> > platform.
> > 
> > Signed-off-by: Shashi Mallela <shashi.mallela@linaro.org>
> > Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> > ---
> >  hw/arm/virt.c         | 28 ++++++++++++++++++++++++++--
> >  include/hw/arm/virt.h |  2 ++
> >  target/arm/kvm_arm.h  |  4 ++--
> >  3 files changed, 30 insertions(+), 4 deletions(-)
> > 
> > diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> > index 81eda46b0b..99cf4f9dbd 100644
> > --- a/hw/arm/virt.c
> > +++ b/hw/arm/virt.c
> > @@ -583,6 +583,12 @@ static void create_its(VirtMachineState *vms)
> >      const char *itsclass = its_class_name();
> >      DeviceState *dev;
> >  
> > +    if (!strcmp(itsclass, "arm-gicv3-its")) {
> > +        if (!vms->tcg_its) {
> > +            itsclass = NULL;
> > +        }
> > +    }
> > +
> >      if (!itsclass) {
> >          /* Do nothing if not supported */
> >          return;
> > @@ -620,7 +626,7 @@ static void create_v2m(VirtMachineState *vms)
> >      vms->msi_controller = VIRT_MSI_CTRL_GICV2M;
> >  }
> >  
> > -static void create_gic(VirtMachineState *vms)
> > +static void create_gic(VirtMachineState *vms, MemoryRegion *mem)
> >  {
> >      MachineState *ms = MACHINE(vms);
> >      /* We create a standalone GIC */
> > @@ -654,6 +660,14 @@ static void create_gic(VirtMachineState *vms)
> >                               nb_redist_regions);
> >          qdev_prop_set_uint32(vms->gic, "redist-region-count[0]",
> > redist0_count);
> >  
> > +        if (!kvm_irqchip_in_kernel()) {
> > +            if (vms->tcg_its) {
> > +                object_property_set_link(OBJECT(vms->gic),
> > "sysmem",
> > +                                         OBJECT(mem),
> > &error_fatal);
> > +                qdev_prop_set_bit(vms->gic, "has-lpi", true);
> > +            }
> > +        }
> > +
> >          if (nb_redist_regions == 2) {
> >              uint32_t redist1_capacity =
> >                      vms->memmap[VIRT_HIGH_GIC_REDIST2].size /
> > GICV3_REDIST_SIZE;
> > @@ -2043,7 +2057,7 @@ static void machvirt_init(MachineState
> > *machine)
> >  
> >      virt_flash_fdt(vms, sysmem, secure_sysmem ?: sysmem);
> >  
> > -    create_gic(vms);
> > +    create_gic(vms, sysmem);
> >  
> >      virt_cpu_post_init(vms, sysmem);
> >  
> > @@ -2746,6 +2760,12 @@ static void virt_instance_init(Object *obj)
> >      } else {
> >          /* Default allows ITS instantiation */
> >          vms->its = true;
> > +
> > +        if (vmc->no_tcg_its) {
> > +            vms->tcg_its = false;
> > +        } else {
> > +            vms->tcg_its = true;
> > +        }
> >      }
> >  
> >      /* Default disallows iommu instantiation */
> > @@ -2795,8 +2815,12 @@ DEFINE_VIRT_MACHINE_AS_LATEST(6, 1)
> >  
> >  static void virt_machine_6_0_options(MachineClass *mc)
> >  {
> > +    VirtMachineClass *vmc = VIRT_MACHINE_CLASS(OBJECT_CLASS(mc));
> > +
> >      virt_machine_6_1_options(mc);
> >      compat_props_add(mc->compat_props, hw_compat_6_0,
> > hw_compat_6_0_len);
> > +    /* qemu ITS was introduced with 6.1 */
> > +    vmc->no_tcg_its = true;
> 
> given it's not going to be in 6.1, shouldn't it be moved to
> virt_machine_6_1_options() with updated comment?
Agreed,moved to virt_machine_6_1_options() and updated comment
> 
> >  }
> >  DEFINE_VIRT_MACHINE(6, 0)
> >  
> > diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
> > index 9661c46699..b461b8d261 100644
> > --- a/include/hw/arm/virt.h
> > +++ b/include/hw/arm/virt.h
> > @@ -120,6 +120,7 @@ struct VirtMachineClass {
> >      MachineClass parent;
> >      bool disallow_affinity_adjustment;
> >      bool no_its;
> > +    bool no_tcg_its;
> >      bool no_pmu;
> >      bool claim_edge_triggered_timers;
> >      bool smbios_old_sys_ver;
> > @@ -141,6 +142,7 @@ struct VirtMachineState {
> >      bool highmem;
> >      bool highmem_ecam;
> >      bool its;
> > +    bool tcg_its;
> >      bool virt;
> >      bool ras;
> >      bool mte;
> > diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
> > index 34f8daa377..0613454975 100644
> > --- a/target/arm/kvm_arm.h
> > +++ b/target/arm/kvm_arm.h
> > @@ -525,8 +525,8 @@ static inline const char *its_class_name(void)
> >          /* KVM implementation requires this capability */
> >          return kvm_direct_msi_enabled() ? "arm-its-kvm" : NULL;
> >      } else {
> > -        /* Software emulation is not implemented yet */
> > -        return NULL;
> > +        /* Software emulation based model */
> > +        return "arm-gicv3-its";
> >      }
> >  }
> >