diff options
Diffstat (limited to 'Documentation/virtual/kvm/hypercalls.txt')
| -rw-r--r-- | Documentation/virtual/kvm/hypercalls.txt | 154 |
1 files changed, 0 insertions, 154 deletions
diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt deleted file mode 100644 index da210651f714..000000000000 --- a/Documentation/virtual/kvm/hypercalls.txt +++ /dev/null @@ -1,154 +0,0 @@ -Linux KVM Hypercall: -=================== -X86: - KVM Hypercalls have a three-byte sequence of either the vmcall or the vmmcall - instruction. The hypervisor can replace it with instructions that are - guaranteed to be supported. - - Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively. - The hypercall number should be placed in rax and the return value will be - placed in rax. No other registers will be clobbered unless explicitly stated - by the particular hypercall. - -S390: - R2-R7 are used for parameters 1-6. In addition, R1 is used for hypercall - number. The return value is written to R2. - - S390 uses diagnose instruction as hypercall (0x500) along with hypercall - number in R1. - - For further information on the S390 diagnose call as supported by KVM, - refer to Documentation/virtual/kvm/s390-diag.txt. - - PowerPC: - It uses R3-R10 and hypercall number in R11. R4-R11 are used as output registers. - Return value is placed in R3. - - KVM hypercalls uses 4 byte opcode, that are patched with 'hypercall-instructions' - property inside the device tree's /hypervisor node. - For more information refer to Documentation/virtual/kvm/ppc-pv.txt - -MIPS: - KVM hypercalls use the HYPCALL instruction with code 0 and the hypercall - number in $2 (v0). Up to four arguments may be placed in $4-$7 (a0-a3) and - the return value is placed in $2 (v0). - -KVM Hypercalls Documentation -=========================== -The template for each hypercall is: -1. Hypercall name. -2. Architecture(s) -3. Status (deprecated, obsolete, active) -4. Purpose - -1. KVM_HC_VAPIC_POLL_IRQ ------------------------- -Architecture: x86 -Status: active -Purpose: Trigger guest exit so that the host can check for pending -interrupts on reentry. - -2. KVM_HC_MMU_OP ------------------------- -Architecture: x86 -Status: deprecated. -Purpose: Support MMU operations such as writing to PTE, -flushing TLB, release PT. - -3. KVM_HC_FEATURES ------------------------- -Architecture: PPC -Status: active -Purpose: Expose hypercall availability to the guest. On x86 platforms, cpuid -used to enumerate which hypercalls are available. On PPC, either device tree -based lookup ( which is also what EPAPR dictates) OR KVM specific enumeration -mechanism (which is this hypercall) can be used. - -4. KVM_HC_PPC_MAP_MAGIC_PAGE ------------------------- -Architecture: PPC -Status: active -Purpose: To enable communication between the hypervisor and guest there is a -shared page that contains parts of supervisor visible register state. -The guest can map this shared page to access its supervisor register through -memory using this hypercall. - -5. KVM_HC_KICK_CPU ------------------------- -Architecture: x86 -Status: active -Purpose: Hypercall used to wakeup a vcpu from HLT state -Usage example : A vcpu of a paravirtualized guest that is busywaiting in guest -kernel mode for an event to occur (ex: a spinlock to become available) can -execute HLT instruction once it has busy-waited for more than a threshold -time-interval. Execution of HLT instruction would cause the hypervisor to put -the vcpu to sleep until occurrence of an appropriate event. Another vcpu of the -same guest can wakeup the sleeping vcpu by issuing KVM_HC_KICK_CPU hypercall, -specifying APIC ID (a1) of the vcpu to be woken up. An additional argument (a0) -is used in the hypercall for future use. - - -6. KVM_HC_CLOCK_PAIRING ------------------------- -Architecture: x86 -Status: active -Purpose: Hypercall used to synchronize host and guest clocks. -Usage: - -a0: guest physical address where host copies -"struct kvm_clock_offset" structure. - -a1: clock_type, ATM only KVM_CLOCK_PAIRING_WALLCLOCK (0) -is supported (corresponding to the host's CLOCK_REALTIME clock). - - struct kvm_clock_pairing { - __s64 sec; - __s64 nsec; - __u64 tsc; - __u32 flags; - __u32 pad[9]; - }; - - Where: - * sec: seconds from clock_type clock. - * nsec: nanoseconds from clock_type clock. - * tsc: guest TSC value used to calculate sec/nsec pair - * flags: flags, unused (0) at the moment. - -The hypercall lets a guest compute a precise timestamp across -host and guest. The guest can use the returned TSC value to -compute the CLOCK_REALTIME for its clock, at the same instant. - -Returns KVM_EOPNOTSUPP if the host does not use TSC clocksource, -or if clock type is different than KVM_CLOCK_PAIRING_WALLCLOCK. - -6. KVM_HC_SEND_IPI ------------------------- -Architecture: x86 -Status: active -Purpose: Send IPIs to multiple vCPUs. - -a0: lower part of the bitmap of destination APIC IDs -a1: higher part of the bitmap of destination APIC IDs -a2: the lowest APIC ID in bitmap -a3: APIC ICR - -The hypercall lets a guest send multicast IPIs, with at most 128 -128 destinations per hypercall in 64-bit mode and 64 vCPUs per -hypercall in 32-bit mode. The destinations are represented by a -bitmap contained in the first two arguments (a0 and a1). Bit 0 of -a0 corresponds to the APIC ID in the third argument (a2), bit 1 -corresponds to the APIC ID a2+1, and so on. - -Returns the number of CPUs to which the IPIs were delivered successfully. - -7. KVM_HC_SCHED_YIELD ------------------------- -Architecture: x86 -Status: active -Purpose: Hypercall used to yield if the IPI target vCPU is preempted - -a0: destination APIC ID - -Usage example: When sending a call-function IPI-many to vCPUs, yield if -any of the IPI target vCPUs was preempted. |