Hi Christoffer, > -----Original Message----- > From: kvmarm-bounces@xxxxxxxxxxxxxxxxxxxxx [mailto:kvmarm- > bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Christoffer Dall > Sent: Monday, July 16, 2018 6:36 PM > To: kvmarm@xxxxxxxxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > Cc: kvm@xxxxxxxxxxxxxxx; Marc Zyngier <marc.zyngier@xxxxxxx>; Andre > Przywara <andre.przywara@xxxxxxx> > Subject: [PATCH v4 10/10] KVM: arm/arm64: vgic: Update documentation of > the GIC devices wrt IIDR > > Update the documentation to reflect the ordering requirements of > restoring the GICD_IIDR register before any other registers and the > effects this has on restoring the interrupt groups for an emulated GICv2 > insttance. > > Also remove some outdated limitations in the documentation while we're > at it. > > Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxx> > --- > Documentation/virtual/kvm/devices/arm-vgic-v3.txt | 8 ++++++++ > Documentation/virtual/kvm/devices/arm-vgic.txt | 15 +++++++++------ > 2 files changed, 17 insertions(+), 6 deletions(-) > > diff --git a/Documentation/virtual/kvm/devices/arm-vgic-v3.txt > b/Documentation/virtual/kvm/devices/arm-vgic-v3.txt > index 2408ab7..eba20ae 100644 > --- a/Documentation/virtual/kvm/devices/arm-vgic-v3.txt > +++ b/Documentation/virtual/kvm/devices/arm-vgic-v3.txt > @@ -100,6 +100,14 @@ Groups: > Note that distributor fields are not banked, but return the same value > regardless of the mpidr used to access the register. > > + GICD_IIDR.Revision is updated when the KVM implementation is changed > in a > + way directly observable by the guest or userspace. Userspace should > read > + GICD_IIDR from KVM and write back the read value to confirm its > expected > + behavior is aligned with the KVM implementation. Userspace should set > + GICD_IIDR before setting any other registers. to ensure the expected > + behavior. > + > + > The GICD_STATUSR and GICR_STATUSR registers are architecturally > defined such > that a write of a clear bit has no effect, whereas a write with a set bit > clears that value. To allow userspace to freely set the values of these two > diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt > b/Documentation/virtual/kvm/devices/arm-vgic.txt > index b3ce126..4ff7635 100644 > --- a/Documentation/virtual/kvm/devices/arm-vgic.txt > +++ b/Documentation/virtual/kvm/devices/arm-vgic.txt > @@ -49,9 +49,15 @@ Groups: > index is specified with the vcpu_index field. Note that most distributor > fields are not banked, but return the same value regardless of the > vcpu_index used to access the register. > - Limitations: > - - Priorities are not implemented, and registers are RAZ/WI > - - Currently only implemented for KVM_DEV_TYPE_ARM_VGIC_V2. > + > + GICD_IIDR.Revision is updated when the KVM implementation of an > emulated > + GICv2 is changed in a way directly observable by the guest or userspace. > + Userspace should read GICD_IIDR from KVM and write back the read > value to > + confirm its expected behavior is aligned with the KVM implementation. > + Userspace should set GICD_IIDR before setting any other registers (both > + KVM_DEV_ARM_VGIC_GRP_DIST_REGS and > KVM_DEV_ARM_VGIC_GRP_CPU_REGS) to ensure > + the expected behavior. Unless GICD_IIDR has been set from userspace, > writes > + to the interrupt group registers (GICD_IGROUPR) are ignored. Newer user-space will write to GICD_IIDR, that mean interrupt-groups are supported otherwise not. And when interrupt-groups are not supported then writes to GICD_IGROUPR are ignored (backward compatibility) Is this understanding correct? Thanks -Bharat > Errors: > -ENXIO: Getting or setting this register is not yet supported > -EBUSY: One or more VCPUs are running > @@ -94,9 +100,6 @@ Groups: > use the lower 5 bits to communicate with the KVM device and must shift > the > value left by 3 places to obtain the actual priority mask level. > > - Limitations: > - - Priorities are not implemented, and registers are RAZ/WI > - - Currently only implemented for KVM_DEV_TYPE_ARM_VGIC_V2. > Errors: > -ENXIO: Getting or setting this register is not yet supported > -EBUSY: One or more VCPUs are running > -- > 2.7.4 > > _______________________________________________ > kvmarm mailing list > kvmarm@xxxxxxxxxxxxxxxxxxxxx > https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flist > s.cs.columbia.edu%2Fmailman%2Flistinfo%2Fkvmarm&data=02%7C01% > 7Cbharat.bhushan%40nxp.com%7C55b2ec9f9b7b4d6e530c08d5eb1d0faf%7C > 686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C636673432404483929&am > p;sdata=RSQwNKkEYC02igGgPVIQmp40VsC9hU%2FFeiMcQBvYJOA%3D&am > p;reserved=0
