[PATCH v3] KVM: arm/arm64: Add VGICv3 save/restore API documentation

[christoffer.dall@linaro.org (Christoffer Dall)]

Factor out the GICv3-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 accesing level triggered IRQ information for GICv3
as well.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
Changes since v2:
 - Changed distributor access to be 32-bits in size
 - Clearly specified data type pointed to by addr field
 - Specified exception behavior for STATUSR registers
 - Added group for level-triggered IRQ status info
 - Removed acks from Marc/Peter as content has changed

 Documentation/virtual/kvm/devices/arm-vgic-v3.txt | 176 ++++++++++++++++++++++
 Documentation/virtual/kvm/devices/arm-vgic.txt    |  21 +--
 2 files changed, 180 insertions(+), 17 deletions(-)
 create mode 100644 Documentation/virtual/kvm/devices/arm-vgic-v3.txt

diff --git a/Documentation/virtual/kvm/devices/arm-vgic-v3.txt b/Documentation/virtual/kvm/devices/arm-vgic-v3.txt
new file mode 100644
index 0000000..69201e8
--- /dev/null
+++ b/Documentation/virtual/kvm/devices/arm-vgic-v3.txt
@@ -0,0 +1,176 @@
+ARM Virtual Generic Interrupt Controller v3 and later (VGICv3)
+==============================================================
+
+
+Device types supported:
+  KVM_DEV_TYPE_ARM_VGIC_V3     ARM Generic Interrupt Controller v3.0
+
+Only one VGIC instance may be instantiated through this 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.  It is not
+possible to create both a GICv3 and GICv2 on the same VM.
+
+Creating a guest GICv3 device requires a host GICv3 as well.
+
+Groups:
+  KVM_DEV_ARM_VGIC_GRP_ADDR
+  Attributes:
+    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_DEV_ARM_VGIC_GRP_DIST_REGS
+  KVM_DEV_ARM_VGIC_GRP_REDIST_REGS
+  Attributes:
+    The attr field of kvm_device_attr encodes two values:
+    bits:     | 63   ....  32  |  31   ....    0 |
+    values:   |      mpidr     |      offset     |
+
+    All distributor regs are (rw, 32-bit) and kvm_device_attr.addr points to a
+    __u32 value.  64-bit registers must be accessed by separately accessing the
+    lower and higher word.
+
+    Writes to read-only registers can be ignored by the kernel.
+
+    KVM_DEV_ARM_VGIC_GRP_DIST_REGS accesses the main distributor registers.
+    KVM_DEV_ARM_VGIC_GRP_REDIST_REGS accesses the redistributor of the CPU
+    specified by the mpidr.
+
+    The offset is relative to the "[Re]Distributor base address" as defined
+    in the GICv3/4 specs.  Getting or setting such a register has the same
+    effect as reading or writing the register on real hardware (except for
+    GICD_STATUS and GICR_STATUSR, see blow), and the mpidr field is used to
+    specify which redistributor is accessed.  The mpidr is ignored for the
+    distributor.
+
+    The mpidr encoding is based on the affinity information in the
+    architecture defined MPIDR, and the field is encoded as follows:
+      | 63 .... 56 | 55 .... 48 | 47 .... 40 | 39 .... 32 |
+      |    Aff3    |    Aff2    |    Aff1    |    Aff0    |
+
+    Note that distributor fields are not banked, but return the same value
+    regardless of the mpidr used to access the register.
+
+    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
+    registers, setting the attributes with the register offsets for these two
+    registers simply sets the non-reserved bits to the value written.
+  Limitations:
+    - Priorities are not implemented, and registers are RAZ/WI
+  Errors:
+    -ENXIO: Getting or setting this register is not yet supported
+    -EBUSY: One or more VCPUs are running
+
+
+  KVM_DEV_ARM_VGIC_CPU_SYSREGS
+  Attributes:
+    The attr field of kvm_device_attr encodes two values:
+    bits:     | 63      ....       32 | 31  ....  16 | 15  ....  0 |
+    values:   |         mpidr         |      RES     |    instr    |
+
+    The mpidr field encodes the CPU ID based on the affinity information in the
+    architecture defined MPIDR, and the field is encoded as follows:
+      | 63 .... 56 | 55 .... 48 | 47 .... 40 | 39 .... 32 |
+      |    Aff3    |    Aff2    |    Aff1    |    Aff0   |
+
+    The instr field encodes the system register to access based on the fields
+    defined in the A64 instruction set encoding for system register access
+    (RES means the bits are reserved for future use and should be zero):
+
+      | 15 ... 14 | 13 ... 11 | 10 ... 7 | 6 ... 3 | 2 ... 0 |
+      |   Op 0    |    Op1    |    CRn   |   CRm   |   Op2   |
+
+    All system regs accessed through this API are (rw, 64-bit) and
+    kvm_device_attr.addr points to a __u64 value.
+
+    KVM_DEV_ARM_VGIC_CPU_SYSREGS accesses the CPU interface registers for the
+    CPU specified by the mpidr field.
+
+
+  Limitations:
+    - Priorities are not implemented, and registers are RAZ/WI
+  Errors:
+    -ENXIO: Getting or setting this register is not yet supported
+    -EBUSY: VCPU is running
+    -EINVAL: Invalid mpidr supplied
+
+
+  KVM_DEV_ARM_VGIC_GRP_NR_IRQS
+  Attributes:
+    A value describing the number of interrupts (SGI, PPI and SPI) for
+    this GIC instance, ranging from 64 to 1024, in increments of 32.
+
+    kvm_device_attr.addr points to a __u32 value.
+
+  Errors:
+    -EINVAL: Value set is out of the expected range
+    -EBUSY: Value has already be set.
+
+
+  KVM_DEV_ARM_VGIC_GRP_CTRL
+  Attributes:
+    KVM_DEV_ARM_VGIC_CTRL_INIT
+      request the initialization of the VGIC, no additional parameter in
+      kvm_device_attr.addr.
+  Errors:
+    -ENXIO: VGIC not properly configured as required prior to calling
+     this attribute
+    -ENODEV: no online VCPU
+    -ENOMEM: memory shortage when allocating vgic internal data
+
+
+  KVM_DEV_ARM_VGIC_GRP_LEVEL_INFO
+  Attributes:
+    The attr field of kvm_device_attr encodes the following values:
+    bits:     | 63      ....       32 | 31   ....    10 | 9  ....  0 |
+    values:   |         mpidr         |      info       |   vINTID   |
+
+    The vINTID specifies which set of IRQs is reported on.
+
+    The info field specifies which information userspace wants to get or set
+    using this interface.  Currently we support two different pieces of
+    information:
+
+      VGIC_LEVEL_INFO_LINE_LEVEL:
+        Get/Set the intput level of the IRQ line for a given IRQ.
+	vINTID must be a multiple of 32.
+
+        kvm_device_attr.addr points to a __u32 value which will contain a
+	bitmap where a set bit means the interrupt level is asserted.
+
+	Bit[n] indicates the status for interrupt vINTID + n.
+
+
+      VGIC_LEVEL_INFO_SOFT_PENDING
+        Get/Set the latch state of a GIVEN level-triggered IRQ as manipulated by
+	guest writes to GICD_SPENDR.
+	vINTID must be a multiple of 32.
+
+        kvm_device_attr.addr points to a __u32 value which will contain a
+	bitmap where a set bit means the guest has set the interrupt by writing
+	to the SPENDR.
+
+	Bit[n] indicates the status for interrupt vINTID + n.
+
+
+    SGIs and any interrupt with a higher ID than the number of interrupts
+    supported, will be RAZ/WI.  LPIs are always edge-triggered and are
+    therefore not supported by this interface.
+
+    PPIs are reported per VCPU as specified in the mpidr field, and SPIs are
+    reported with the same value regardless of the mpidr specified.
+
+    The mpidr field encodes the CPU ID based on the affinity information in the
+    architecture defined MPIDR, and the field is encoded as follows:
+      | 63 .... 56 | 55 .... 48 | 47 .... 40 | 39 .... 32 |
+      |    Aff3    |    Aff2    |    Aff1    |    Aff0   |
diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt b/Documentation/virtual/kvm/devices/arm-vgic.txt
index 59541d4..257b854 100644
--- a/Documentation/virtual/kvm/devices/arm-vgic.txt
+++ b/Documentation/virtual/kvm/devices/arm-vgic.txt
@@ -3,16 +3,16 @@ ARM Virtual Generic Interrupt Controller (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
 
 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, see arm-vgic-v3.txt.  It is not possible to create both a GICv3 and
+GICv2 device on the same VM.
 
 Groups:
   KVM_DEV_ARM_VGIC_GRP_ADDR
@@ -27,19 +27,6 @@ Groups:
       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_DEV_ARM_VGIC_GRP_DIST_REGS
   Attributes:
     The attr field of kvm_device_attr encodes two values:
-- 
2.1.2.330.g565301e.dirty