On Tue, Apr 24, 2018 at 05:50:37PM +0100, Peter Maydell wrote: > On 24 April 2018 at 17:46, Christoffer Dall <christoffer.dall@xxxxxxx> wrote: > > On Fri, Apr 13, 2018 at 10:20:48AM +0200, Eric Auger wrote: > >> --- a/Documentation/virtual/kvm/devices/arm-vgic-v3.txt > >> +++ b/Documentation/virtual/kvm/devices/arm-vgic-v3.txt > >> @@ -27,9 +27,32 @@ Groups: > >> VCPU and all of the redistributor pages are contiguous. > >> Only valid for KVM_DEV_TYPE_ARM_VGIC_V3. > >> This address needs to be 64K aligned. > >> + > >> + KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION (rw, 64-bit) > >> + The attr field of kvm_device_attr encodes 3 values: > >> + bits: | 63 .... 52 | 51 .... 16 | 15 - 12 |11 - 0 > >> + values: | count | base | flags | index > >> + - index encodes the unique redistributor region index > > > > I'm not entirely sure I understand the purpose of the index field. > > Isn't a redistributor region identified uniquely by its base address? > > You need a way to tell the difference beween: > (1) redistributors for CPUs 0..63 at 0x40000000, redistributors > for 64..127 at 0x80000000 > (2) redistributors for CPUs 0..63 at 0x80000000, redistributors > for 64..127 at 0x40000000 > > The index field tells you which order the redistributor > regions go in. ah, right. This could be implied by the order creating the regions though, but ok, in that case it's nicer for userspace to state it explicitly. Thanks, -Christoffer
