diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/virt/kvm/hypercalls.rst (renamed from Documentation/virt/kvm/hypercalls.txt) | 129 | ||||
| -rw-r--r-- | Documentation/virt/kvm/index.rst | 2 |
2 files changed, 75 insertions, 56 deletions
diff --git a/Documentation/virt/kvm/hypercalls.txt b/Documentation/virt/kvm/hypercalls.rst index 5f6d291bd004..dbaf207e560d 100644 --- a/Documentation/virt/kvm/hypercalls.txt +++ b/Documentation/virt/kvm/hypercalls.rst @@ -1,5 +1,9 @@ -Linux KVM Hypercall: +.. SPDX-License-Identifier: GPL-2.0 + +=================== +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 @@ -20,7 +24,7 @@ S390: For further information on the S390 diagnose call as supported by KVM, refer to Documentation/virt/kvm/s390-diag.txt. - PowerPC: +PowerPC: It uses R3-R10 and hypercall number in R11. R4-R11 are used as output registers. Return value is placed in R3. @@ -34,7 +38,8 @@ MIPS: the return value is placed in $2 (v0). KVM Hypercalls Documentation -=========================== +============================ + The template for each hypercall is: 1. Hypercall name. 2. Architecture(s) @@ -43,56 +48,64 @@ The template for each hypercall is: 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. + +: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. +---------------- + +: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. +------------------ + +: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. +---------------------------- + +: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. +------------------ + +: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. +----------------------- +:Architecture: x86 +:Status: active +:Purpose: Hypercall used to synchronize host and guest clocks. + Usage: a0: guest physical address where host copies @@ -101,6 +114,8 @@ a0: guest physical address where host copies 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; @@ -123,15 +138,16 @@ 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. +------------------ + +: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 +- 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 @@ -143,12 +159,13 @@ 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 +--------------------- + +: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. +:Usage example: When sending a call-function IPI-many to vCPUs, yield if + any of the IPI target vCPUs was preempted. diff --git a/Documentation/virt/kvm/index.rst b/Documentation/virt/kvm/index.rst index 6fe79185b9bc..ac83bc588f7e 100644 --- a/Documentation/virt/kvm/index.rst +++ b/Documentation/virt/kvm/index.rst @@ -11,8 +11,10 @@ KVM amd-memory-encryption cpuid halt-polling + hypercalls msr vcpu-requests arm/index + devices/index |