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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
instance.

Also remove some outdated limitations in the documentation while we're
at it.

Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Christoffer Dall 2018-07-16 15:06:27 +02:00 committed by Marc Zyngier
parent 32f8777ed9
commit 327432c246
2 changed files with 17 additions and 6 deletions
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8
Documentation/virtual/kvm/devices/arm-vgic-v3.txt
View File

@ -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

15
Documentation/virtual/kvm/devices/arm-vgic.txt
View File

@ -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.
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