api.txt

Target: vcpu
Parameters: args[0] is the address of a struct kvm_config_tlb
Returns: 0 on success; -1 on error

struct kvm_config_tlb {
	__u64 params;
	__u64 array;
	__u32 mmu_type;
	__u32 array_len;
};

Configures the virtual CPU's TLB array, establishing a shared memory area
between userspace and KVM.  The "params" and "array" fields are userspace
addresses of mmu-type-specific data structures.  The "array_len" field is an
safety mechanism, and should be set to the size in bytes of the memory that
userspace has reserved for the array.  It must be at least the size dictated
by "mmu_type" and "params".

While KVM_RUN is active, the shared region is under control of KVM.  Its
contents are undefined, and any modification by userspace results in
boundedly undefined behavior.

On return from KVM_RUN, the shared region will reflect the current state of
the guest's TLB.  If userspace makes any changes, it must call KVM_DIRTY_TLB
to tell KVM which entries have been changed, prior to calling KVM_RUN again
on this vcpu.

For mmu types KVM_MMU_FSL_BOOKE_NOHV and KVM_MMU_FSL_BOOKE_HV:
 - The "params" field is of type "struct kvm_book3e_206_tlb_params".
 - The "array" field points to an array of type "struct
   kvm_book3e_206_tlb_entry".
 - The array consists of all entries in the first TLB, followed by all
   entries in the second TLB.
 - Within a TLB, entries are ordered first by increasing set number.  Within a
   set, entries are ordered by way (increasing ESEL).
 - The hash for determining set number in TLB0 is: (MAS2 >> 12) & (num_sets - 1)
   where "num_sets" is the tlb_sizes[] value divided by the tlb_ways[] value.
 - The tsize field of mas1 shall be set to 4K on TLB0, even though the
   hardware ignores this value for TLB0.

6.4 KVM_CAP_S390_CSS_SUPPORT

Architectures: s390
Target: vcpu
Parameters: none
Returns: 0 on success; -1 on error

This capability enables support for handling of channel I/O instructions.

TEST PENDING INTERRUPTION and the interrupt portion of TEST SUBCHANNEL are
handled in-kernel, while the other I/O instructions are passed to userspace.

When this capability is enabled, KVM_EXIT_S390_TSCH will occur on TEST
SUBCHANNEL intercepts.

Note that even though this capability is enabled per-vcpu, the complete
virtual machine is affected.

6.5 KVM_CAP_PPC_EPR

Architectures: ppc
Target: vcpu
Parameters: args[0] defines whether the proxy facility is active
Returns: 0 on success; -1 on error

This capability enables or disables the delivery of interrupts through the
external proxy facility.

When enabled (args[0] != 0), every time the guest gets an external interrupt
delivered, it automatically exits into user space with a KVM_EXIT_EPR exit
to receive the topmost interrupt vector.

When disabled (args[0] == 0), behavior is as if this facility is unsupported.

When this capability is enabled, KVM_EXIT_EPR can occur.

6.6 KVM_CAP_IRQ_MPIC

Architectures: ppc
Parameters: args[0] is the MPIC device fd
            args[1] is the MPIC CPU number for this vcpu

This capability connects the vcpu to an in-kernel MPIC device.

6.7 KVM_CAP_IRQ_XICS

Architectures: ppc
Target: vcpu
Parameters: args[0] is the XICS device fd
            args[1] is the XICS CPU number (server ID) for this vcpu

This capability connects the vcpu to an in-kernel XICS device.

6.8 KVM_CAP_S390_IRQCHIP

Architectures: s390
Target: vm
Parameters: none

This capability enables the in-kernel irqchip for s390. Please refer to
"4.24 KVM_CREATE_IRQCHIP" for details.

7. Capabilities that can be enabled on VMs
------------------------------------------

There are certain capabilities that change the behavior of the virtual
machine when enabled. To enable them, please see section 4.37. Below
you can find a list of capabilities and what their effect on the VM
is when enabling them.

The following information is provided along with the description:

  Architectures: which instruction set architectures provide this ioctl.
      x86 includes both i386 and x86_64.

  Parameters: what parameters are accepted by the capability.

  Returns: the return value.  General error numbers (EBADF, ENOMEM, EINVAL)
      are not detailed, but errors with specific meanings are.


7.1 KVM_CAP_PPC_ENABLE_HCALL

Architectures: ppc
Parameters: args[0] is the sPAPR hcall number
	    args[1] is 0 to disable, 1 to enable in-kernel handling

This capability controls whether individual sPAPR hypercalls (hcalls)
get handled by the kernel or not.  Enabling or disabling in-kernel
handling of an hcall is effective across the VM.  On creation, an
initial set of hcalls are enabled for in-kernel handling, which
consists of those hcalls for which in-kernel handlers were implemented
before this capability was implemented.  If disabled, the kernel will
not to attempt to handle the hcall, but will always exit to userspace
to handle it.  Note that it may not make sense to enable some and
disable others of a group of related hcalls, but KVM does not prevent
userspace from doing that.

If the hcall number specified is not one that has an in-kernel
implementation, the KVM_ENABLE_CAP ioctl will fail with an EINVAL
error.