KVM: arm/arm64: Add VGICv3 save/restore API documentation

Factor out the GICv3 and ITS-specific documentation into a separate
documentation file.  Add description for how to access distributor,
redistributor, and CPU interface registers for GICv3 in this new file,
and add a group for accessing level triggered IRQ information for GICv3
as well.

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

1 files changed, 17 insertions, 35 deletions

diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt b/Documentation/virtual/kvm/devices/arm-vgic.txt
index 89182f80cc7f..76e61c883347 100644
--- a/Documentation/virtual/kvm/devices/arm-vgic.txt
+++ b/Documentation/virtual/kvm/devices/arm-vgic.txt
@@ -1,24 +1,19 @@
-ARM Virtual Generic Interrupt Controller (VGIC)
-===============================================
+ARM Virtual Generic Interrupt Controller v2 (VGIC)
+==================================================
 
 Device types supported:
   KVM_DEV_TYPE_ARM_VGIC_V2     ARM Generic Interrupt Controller v2.0
-  KVM_DEV_TYPE_ARM_VGIC_V3     ARM Generic Interrupt Controller v3.0
-  KVM_DEV_TYPE_ARM_VGIC_ITS    ARM Interrupt Translation Service Controller
 
-Only one VGIC instance of the V2/V3 types above may be instantiated through
-either this API or the legacy KVM_CREATE_IRQCHIP api.  The created VGIC will
-act as the VM interrupt controller, requiring emulated user-space devices to
-inject interrupts to the VGIC instead of directly to CPUs.
+Only one VGIC instance may be instantiated through either this API or the
+legacy KVM_CREATE_IRQCHIP API.  The created VGIC will act as the VM interrupt
+controller, requiring emulated user-space devices to inject interrupts to the
+VGIC instead of directly to CPUs.
 
-Creating a guest GICv3 device requires a host GICv3 as well.
-GICv3 implementations with hardware compatibility support allow a guest GICv2
-as well.
+GICv3 implementations with hardware compatibility support allow creating a
+guest GICv2 through this interface.  For information on creating a guest GICv3
+device and guest ITS devices, see arm-vgic-v3.txt.  It is not possible to
+create both a GICv3 and GICv2 device on the same VM.
 
-Creating a virtual ITS controller requires a host GICv3 (but does not depend
-on having physical ITS controllers).
-There can be multiple ITS controllers per guest, each of them has to have
-a separate, non-overlapping MMIO region.
 
 Groups:
   KVM_DEV_ARM_VGIC_GRP_ADDR
@@ -32,26 +27,13 @@ Groups:
       Base address in the guest physical address space of the GIC virtual cpu
       interface register mappings. Only valid for KVM_DEV_TYPE_ARM_VGIC_V2.
       This address needs to be 4K aligned and the region covers 4 KByte.
-
-    KVM_VGIC_V3_ADDR_TYPE_DIST (rw, 64-bit)
-      Base address in the guest physical address space of the GICv3 distributor
-      register mappings. Only valid for KVM_DEV_TYPE_ARM_VGIC_V3.
-      This address needs to be 64K aligned and the region covers 64 KByte.
-
-    KVM_VGIC_V3_ADDR_TYPE_REDIST (rw, 64-bit)
-      Base address in the guest physical address space of the GICv3
-      redistributor register mappings. There are two 64K pages for each
-      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_ITS (rw, 64-bit)
-      Base address in the guest physical address space of the GICv3 ITS
-      control register frame. The ITS allows MSI(-X) interrupts to be
-      injected into guests. This extension is optional. If the kernel
-      does not support the ITS, the call returns -ENODEV.
-      Only valid for KVM_DEV_TYPE_ARM_VGIC_ITS.
-      This address needs to be 64K aligned and the region covers 128K.
+  Errors:
+    -E2BIG:  Address outside of addressable IPA range
+    -EINVAL: Incorrectly aligned address
+    -EEXIST: Address already configured
+    -ENXIO:  The group or attribute is unknown/unsupported for this device
+             or hardware support is missing.
+    -EFAULT: Invalid user pointer for attr->addr.
 
   KVM_DEV_ARM_VGIC_GRP_DIST_REGS
   Attributes: