Based on kernel version 4.16.1. Page generated on 2018-04-09 11:53 EST.
1 ARM Virtual Interrupt Translation Service (ITS) 2 =============================================== 3 4 Device types supported: 5 KVM_DEV_TYPE_ARM_VGIC_ITS ARM Interrupt Translation Service Controller 6 7 The ITS allows MSI(-X) interrupts to be injected into guests. This extension is 8 optional. Creating a virtual ITS controller also requires a host GICv3 (see 9 arm-vgic-v3.txt), but does not depend on having physical ITS controllers. 10 11 There can be multiple ITS controllers per guest, each of them has to have 12 a separate, non-overlapping MMIO region. 13 14 15 Groups: 16 KVM_DEV_ARM_VGIC_GRP_ADDR 17 Attributes: 18 KVM_VGIC_ITS_ADDR_TYPE (rw, 64-bit) 19 Base address in the guest physical address space of the GICv3 ITS 20 control register frame. 21 This address needs to be 64K aligned and the region covers 128K. 22 Errors: 23 -E2BIG: Address outside of addressable IPA range 24 -EINVAL: Incorrectly aligned address 25 -EEXIST: Address already configured 26 -EFAULT: Invalid user pointer for attr->addr. 27 -ENODEV: Incorrect attribute or the ITS is not supported. 28 29 30 KVM_DEV_ARM_VGIC_GRP_CTRL 31 Attributes: 32 KVM_DEV_ARM_VGIC_CTRL_INIT 33 request the initialization of the ITS, no additional parameter in 34 kvm_device_attr.addr. 35 36 KVM_DEV_ARM_ITS_CTRL_RESET 37 reset the ITS, no additional parameter in kvm_device_attr.addr. 38 See "ITS Reset State" section. 39 40 KVM_DEV_ARM_ITS_SAVE_TABLES 41 save the ITS table data into guest RAM, at the location provisioned 42 by the guest in corresponding registers/table entries. 43 44 The layout of the tables in guest memory defines an ABI. The entries 45 are laid out in little endian format as described in the last paragraph. 46 47 KVM_DEV_ARM_ITS_RESTORE_TABLES 48 restore the ITS tables from guest RAM to ITS internal structures. 49 50 The GICV3 must be restored before the ITS and all ITS registers but 51 the GITS_CTLR must be restored before restoring the ITS tables. 52 53 The GITS_IIDR read-only register must also be restored before 54 calling KVM_DEV_ARM_ITS_RESTORE_TABLES as the IIDR revision field 55 encodes the ABI revision. 56 57 The expected ordering when restoring the GICv3/ITS is described in section 58 "ITS Restore Sequence". 59 60 Errors: 61 -ENXIO: ITS not properly configured as required prior to setting 62 this attribute 63 -ENOMEM: Memory shortage when allocating ITS internal data 64 -EINVAL: Inconsistent restored data 65 -EFAULT: Invalid guest ram access 66 -EBUSY: One or more VCPUS are running 67 -EACCES: The virtual ITS is backed by a physical GICv4 ITS, and the 68 state is not available 69 70 KVM_DEV_ARM_VGIC_GRP_ITS_REGS 71 Attributes: 72 The attr field of kvm_device_attr encodes the offset of the 73 ITS register, relative to the ITS control frame base address 74 (ITS_base). 75 76 kvm_device_attr.addr points to a __u64 value whatever the width 77 of the addressed register (32/64 bits). 64 bit registers can only 78 be accessed with full length. 79 80 Writes to read-only registers are ignored by the kernel except for: 81 - GITS_CREADR. It must be restored otherwise commands in the queue 82 will be re-executed after restoring CWRITER. GITS_CREADR must be 83 restored before restoring the GITS_CTLR which is likely to enable the 84 ITS. Also it must be restored after GITS_CBASER since a write to 85 GITS_CBASER resets GITS_CREADR. 86 - GITS_IIDR. The Revision field encodes the table layout ABI revision. 87 In the future we might implement direct injection of virtual LPIs. 88 This will require an upgrade of the table layout and an evolution of 89 the ABI. GITS_IIDR must be restored before calling 90 KVM_DEV_ARM_ITS_RESTORE_TABLES. 91 92 For other registers, getting or setting a register has the same 93 effect as reading/writing the register on real hardware. 94 Errors: 95 -ENXIO: Offset does not correspond to any supported register 96 -EFAULT: Invalid user pointer for attr->addr 97 -EINVAL: Offset is not 64-bit aligned 98 -EBUSY: one or more VCPUS are running 99 100 ITS Restore Sequence: 101 ------------------------- 102 103 The following ordering must be followed when restoring the GIC and the ITS: 104 a) restore all guest memory and create vcpus 105 b) restore all redistributors 106 c) provide the its base address 107 (KVM_DEV_ARM_VGIC_GRP_ADDR) 108 d) restore the ITS in the following order: 109 1. Restore GITS_CBASER 110 2. Restore all other GITS_ registers, except GITS_CTLR! 111 3. Load the ITS table data (KVM_DEV_ARM_ITS_RESTORE_TABLES) 112 4. Restore GITS_CTLR 113 114 Then vcpus can be started. 115 116 ITS Table ABI REV0: 117 ------------------- 118 119 Revision 0 of the ABI only supports the features of a virtual GICv3, and does 120 not support a virtual GICv4 with support for direct injection of virtual 121 interrupts for nested hypervisors. 122 123 The device table and ITT are indexed by the DeviceID and EventID, 124 respectively. The collection table is not indexed by CollectionID, and the 125 entries in the collection are listed in no particular order. 126 All entries are 8 bytes. 127 128 Device Table Entry (DTE): 129 130 bits: | 63| 62 ... 49 | 48 ... 5 | 4 ... 0 | 131 values: | V | next | ITT_addr | Size | 132 133 where; 134 - V indicates whether the entry is valid. If not, other fields 135 are not meaningful. 136 - next: equals to 0 if this entry is the last one; otherwise it 137 corresponds to the DeviceID offset to the next DTE, capped by 138 2^14 -1. 139 - ITT_addr matches bits [51:8] of the ITT address (256 Byte aligned). 140 - Size specifies the supported number of bits for the EventID, 141 minus one 142 143 Collection Table Entry (CTE): 144 145 bits: | 63| 62 .. 52 | 51 ... 16 | 15 ... 0 | 146 values: | V | RES0 | RDBase | ICID | 147 148 where: 149 - V indicates whether the entry is valid. If not, other fields are 150 not meaningful. 151 - RES0: reserved field with Should-Be-Zero-or-Preserved behavior. 152 - RDBase is the PE number (GICR_TYPER.Processor_Number semantic), 153 - ICID is the collection ID 154 155 Interrupt Translation Entry (ITE): 156 157 bits: | 63 ... 48 | 47 ... 16 | 15 ... 0 | 158 values: | next | pINTID | ICID | 159 160 where: 161 - next: equals to 0 if this entry is the last one; otherwise it corresponds 162 to the EventID offset to the next ITE capped by 2^16 -1. 163 - pINTID is the physical LPI ID; if zero, it means the entry is not valid 164 and other fields are not meaningful. 165 - ICID is the collection ID 166 167 ITS Reset State: 168 ---------------- 169 170 RESET returns the ITS to the same state that it was when first created and 171 initialized. When the RESET command returns, the following things are 172 guaranteed: 173 174 - The ITS is not enabled and quiescent 175 GITS_CTLR.Enabled = 0 .Quiescent=1 176 - There is no internally cached state 177 - No collection or device table are used 178 GITS_BASER<n>.Valid = 0 179 - GITS_CBASER = 0, GITS_CREADR = 0, GITS_CWRITER = 0 180 - The ABI version is unchanged and remains the one set when the ITS 181 device was first created.