[PATCH v6] KVM: arm/arm64: Add VGICv3 save/restore API documentation
Christoffer Dall
christoffer.dall at linaro.org
Tue Jul 26 04:21:03 PDT 2016
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: Peter Maydell <peter.maydell at linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
---
Changes since v5:
- Rearrange ITS description
- Fix typos
- Add Peter's reviewed-by tag.
Changes since v4:
- Clarify register reads as per Peter's comments on v4
- Factored out ITS documenation into separate file
- Clarified error conditions on all GRP_ADDR groups
- Renamed KVM_VGIC_V3_ADDR_TYPE_ITS to KVM_VGIC_ITS_ADDR_TYPE in the
documentation to be in line with the code.
- Did not apply Peter's reviewed-by due to the conflicts and updates
related to the ITS.
Changes since v3:
- Fix typos
- Clarified level register containing 32 IRQs
- Removed limitations about priority support which are no longer true
- Special-case the SPENDR register accesses to access the latch state
and the CPENDR register accesses to be RAZ/WI.
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-its.txt | 38 ++++
Documentation/virtual/kvm/devices/arm-vgic-v3.txt | 207 +++++++++++++++++++++
Documentation/virtual/kvm/devices/arm-vgic.txt | 52 ++----
3 files changed, 262 insertions(+), 35 deletions(-)
create mode 100644 Documentation/virtual/kvm/devices/arm-vgic-its.txt
create mode 100644 Documentation/virtual/kvm/devices/arm-vgic-v3.txt
diff --git a/Documentation/virtual/kvm/devices/arm-vgic-its.txt b/Documentation/virtual/kvm/devices/arm-vgic-its.txt
new file mode 100644
index 0000000..6081a5b
--- /dev/null
+++ b/Documentation/virtual/kvm/devices/arm-vgic-its.txt
@@ -0,0 +1,38 @@
+ARM Virtual Interrupt Translation Service (ITS)
+===============================================
+
+Device types supported:
+ KVM_DEV_TYPE_ARM_VGIC_ITS ARM Interrupt Translation Service Controller
+
+The ITS allows MSI(-X) interrupts to be injected into guests. This extension is
+optional. Creating a virtual ITS controller also requires a host GICv3 (see
+arm-vgic-v3.txt), 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
+ Attributes:
+ KVM_VGIC_ITS_ADDR_TYPE (rw, 64-bit)
+ Base address in the guest physical address space of the GICv3 ITS
+ control register frame.
+ 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
+ -EFAULT: Invalid user pointer for attr->addr.
+ -ENODEV: Incorrect attribute or the ITS is not supported.
+
+
+ KVM_DEV_ARM_VGIC_GRP_CTRL
+ Attributes:
+ KVM_DEV_ARM_VGIC_CTRL_INIT
+ request the initialization of the ITS, no additional parameter in
+ kvm_device_attr.addr.
+ Errors:
+ -ENXIO: ITS not properly configured as required prior to setting
+ this attribute
+ -ENOMEM: Memory shortage when allocating ITS internal data
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..017e085
--- /dev/null
+++ b/Documentation/virtual/kvm/devices/arm-vgic-v3.txt
@@ -0,0 +1,207 @@
+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.
+ 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
+ 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 are 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 the
+ following registers: GICD_STATUSR, GICR_STATUSR, GICD_ISPENDR,
+ GICR_ISPENDR0, GICD_ICPENDR, and GICR_ICPENDR0. These registers behave
+ differently when accessed via this interface compared to their
+ architecturally defined behavior to allow software a full view of the
+ VGIC's internal state.
+
+ 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.
+
+
+ Accesses (reads and writes) to the GICD_ISPENDR register region and
+ GICR_ISPENDR0 registers get/set the value of the latched pending state for
+ the interrupts.
+
+ This is identical to the value returned by a guest read from ISPENDR for an
+ edge triggered interrupt, but may differ for level triggered interrupts.
+ For edge triggered interrupts, once an interrupt becomes pending (whether
+ because of an edge detected on the input line or because of a guest write
+ to ISPENDR) this state is "latched", and only cleared when either the
+ interrupt is activated or when the guest writes to ICPENDR. A level
+ triggered interrupt may be pending either because the level input is held
+ high by a device, or because of a guest write to the ISPENDR register. Only
+ ISPENDR writes are latched; if the device lowers the line level then the
+ interrupt is no longer pending unless the guest also wrote to ISPENDR, and
+ conversely writes to ICPENDR or activations of the interrupt do not clear
+ the pending status if the line level is still being held high. (These
+ rules are documented in the GICv3 specification descriptions of the ICPENDR
+ and ISPENDR registers.) For a level triggered interrupt the value accessed
+ here is that of the latch which is set by ISPENDR and cleared by ICPENDR or
+ interrupt activation, whereas the value returned by a guest read from
+ ISPENDR is the logical OR of the latch value and the input line level.
+
+ Raw access to the latch state is provided to userspace so that it can save
+ and restore the entire GIC internal state (which is defined by the
+ combination of the current input line level and the latch state, and cannot
+ be deduced from purely the line level and the value of the ISPENDR
+ registers).
+
+ Accesses to GICD_ICPENDR register region and GICR_ICPENDR0 registers have
+ RAZ/WI semantics, meaning that reads always return 0 and writes are always
+ ignored.
+
+ 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.
+
+ 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 input level of the IRQ line for a set of 32 contiguously
+ numbered interrupts.
+ 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.
+
+ 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 89182f8..76e61c8 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:
--
2.9.0
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