Hi Will,
On 26/01/15 11:30, Will Deacon wrote:
> On Fri, Jan 23, 2015 at 04:35:10PM +0000, Andre Przywara wrote:
>> Add the command line parameter "--gicv3" to request GICv3 emulation
>> in the kernel. Connect that to the already existing GICv3 code.
>>
>> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
>> ---
>> tools/kvm/arm/aarch64/arm-cpu.c | 5 ++++-
>> .../kvm/arm/aarch64/include/kvm/kvm-config-arch.h | 4 +++-
>> tools/kvm/arm/gic.c | 14 ++++++++++++++
>> tools/kvm/arm/include/arm-common/kvm-config-arch.h | 1 +
>> tools/kvm/arm/kvm-cpu.c | 2 +-
>> tools/kvm/arm/kvm.c | 3 ++-
>> 6 files changed, 25 insertions(+), 4 deletions(-)
>>
>> diff --git a/tools/kvm/arm/aarch64/arm-cpu.c b/tools/kvm/arm/aarch64/arm-cpu.c
>> index a70d6bb..46d6d6a 100644
>> --- a/tools/kvm/arm/aarch64/arm-cpu.c
>> +++ b/tools/kvm/arm/aarch64/arm-cpu.c
>> @@ -12,7 +12,10 @@
>> static void generate_fdt_nodes(void *fdt, struct kvm *kvm, u32 gic_phandle)
>> {
>> int timer_interrupts[4] = {13, 14, 11, 10};
>> - gic__generate_fdt_nodes(fdt, gic_phandle, KVM_DEV_TYPE_ARM_VGIC_V2);
>> + gic__generate_fdt_nodes(fdt, gic_phandle,
>> + kvm->cfg.arch.gicv3 ?
>> + KVM_DEV_TYPE_ARM_VGIC_V3 :
>> + KVM_DEV_TYPE_ARM_VGIC_V2);
>> timer__generate_fdt_nodes(fdt, kvm, timer_interrupts);
>> }
>>
>> diff --git a/tools/kvm/arm/aarch64/include/kvm/kvm-config-arch.h b/tools/kvm/arm/aarch64/include/kvm/kvm-config-arch.h
>> index 89860ae..106e52f 100644
>> --- a/tools/kvm/arm/aarch64/include/kvm/kvm-config-arch.h
>> +++ b/tools/kvm/arm/aarch64/include/kvm/kvm-config-arch.h
>> @@ -3,7 +3,9 @@
>>
>> #define ARM_OPT_ARCH_RUN(cfg) \
>> OPT_BOOLEAN('\0', "aarch32", &(cfg)->aarch32_guest, \
>> - "Run AArch32 guest"),
>> + "Run AArch32 guest"), \
>> + OPT_BOOLEAN('\0', "gicv3", &(cfg)->gicv3, \
>> + "Use a GICv3 interrupt controller in the guest"),
>
> On a GICv3-capable system, why would I *not* want to enable this option?
> In other words, could we make this the default behaviour on systems that
> support it, and if you need an override then it should be something like
> --force-gicv2.
Well, you could have a guest kernel < 3.17, which does not have GICv3
support. In general I consider GICv2 better tested, so I reckon that
people will only want to use GICv3 emulation if there is a need for it
(non-compat GICv3 host or more than 8 VCPUs in the guest). That probably
changes over time, but for the time being I'd better keep the default at
GICv2 emulation.
Having said that, there could be a fallback in case GICv2 emulation is
not available. Let me take a look at that.
Also thinking about the future (ITS emulation) I found that I'd like to
replace this option with something more generic like --irqchip=.
Cheers,
Andre.
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