mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 03:10:12 +00:00
![Daniel Mack](/assets/img/avatar_default.png)
In particular, several occurances of funny versions of 'success', 'unknown', 'therefore', 'acknowledge', 'argument', 'achieve', 'address', 'beginning', 'desirable', 'separate' and 'necessary' are fixed. Signed-off-by: Daniel Mack <daniel@caiaq.de> Cc: Joe Perches <joe@perches.com> Cc: Junio C Hamano <gitster@pobox.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
125 lines
5.5 KiB
Text
125 lines
5.5 KiB
Text
*** BIG FAT WARNING ***
|
|
The kvm module is currently in EXPERIMENTAL state for s390. This means that
|
|
the interface to the module is not yet considered to remain stable. Thus, be
|
|
prepared that we keep breaking your userspace application and guest
|
|
compatibility over and over again until we feel happy with the result. Make sure
|
|
your guest kernel, your host kernel, and your userspace launcher are in a
|
|
consistent state.
|
|
|
|
This Documentation describes the unique ioctl calls to /dev/kvm, the resulting
|
|
kvm-vm file descriptors, and the kvm-vcpu file descriptors that differ from x86.
|
|
|
|
1. ioctl calls to /dev/kvm
|
|
KVM does support the following ioctls on s390 that are common with other
|
|
architectures and do behave the same:
|
|
KVM_GET_API_VERSION
|
|
KVM_CREATE_VM (*) see note
|
|
KVM_CHECK_EXTENSION
|
|
KVM_GET_VCPU_MMAP_SIZE
|
|
|
|
Notes:
|
|
* KVM_CREATE_VM may fail on s390, if the calling process has multiple
|
|
threads and has not called KVM_S390_ENABLE_SIE before.
|
|
|
|
In addition, on s390 the following architecture specific ioctls are supported:
|
|
ioctl: KVM_S390_ENABLE_SIE
|
|
args: none
|
|
see also: include/linux/kvm.h
|
|
This call causes the kernel to switch on PGSTE in the user page table. This
|
|
operation is needed in order to run a virtual machine, and it requires the
|
|
calling process to be single-threaded. Note that the first call to KVM_CREATE_VM
|
|
will implicitly try to switch on PGSTE if the user process has not called
|
|
KVM_S390_ENABLE_SIE before. User processes that want to launch multiple threads
|
|
before creating a virtual machine have to call KVM_S390_ENABLE_SIE, or will
|
|
observe an error calling KVM_CREATE_VM. Switching on PGSTE is a one-time
|
|
operation, is not reversible, and will persist over the entire lifetime of
|
|
the calling process. It does not have any user-visible effect other than a small
|
|
performance penalty.
|
|
|
|
2. ioctl calls to the kvm-vm file descriptor
|
|
KVM does support the following ioctls on s390 that are common with other
|
|
architectures and do behave the same:
|
|
KVM_CREATE_VCPU
|
|
KVM_SET_USER_MEMORY_REGION (*) see note
|
|
KVM_GET_DIRTY_LOG (**) see note
|
|
|
|
Notes:
|
|
* kvm does only allow exactly one memory slot on s390, which has to start
|
|
at guest absolute address zero and at a user address that is aligned on any
|
|
page boundary. This hardware "limitation" allows us to have a few unique
|
|
optimizations. The memory slot doesn't have to be filled
|
|
with memory actually, it may contain sparse holes. That said, with different
|
|
user memory layout this does still allow a large flexibility when
|
|
doing the guest memory setup.
|
|
** KVM_GET_DIRTY_LOG doesn't work properly yet. The user will receive an empty
|
|
log. This ioctl call is only needed for guest migration, and we intend to
|
|
implement this one in the future.
|
|
|
|
In addition, on s390 the following architecture specific ioctls for the kvm-vm
|
|
file descriptor are supported:
|
|
ioctl: KVM_S390_INTERRUPT
|
|
args: struct kvm_s390_interrupt *
|
|
see also: include/linux/kvm.h
|
|
This ioctl is used to submit a floating interrupt for a virtual machine.
|
|
Floating interrupts may be delivered to any virtual cpu in the configuration.
|
|
Only some interrupt types defined in include/linux/kvm.h make sense when
|
|
submitted as floating interrupts. The following interrupts are not considered
|
|
to be useful as floating interrupts, and a call to inject them will result in
|
|
-EINVAL error code: program interrupts and interprocessor signals. Valid
|
|
floating interrupts are:
|
|
KVM_S390_INT_VIRTIO
|
|
KVM_S390_INT_SERVICE
|
|
|
|
3. ioctl calls to the kvm-vcpu file descriptor
|
|
KVM does support the following ioctls on s390 that are common with other
|
|
architectures and do behave the same:
|
|
KVM_RUN
|
|
KVM_GET_REGS
|
|
KVM_SET_REGS
|
|
KVM_GET_SREGS
|
|
KVM_SET_SREGS
|
|
KVM_GET_FPU
|
|
KVM_SET_FPU
|
|
|
|
In addition, on s390 the following architecture specific ioctls for the
|
|
kvm-vcpu file descriptor are supported:
|
|
ioctl: KVM_S390_INTERRUPT
|
|
args: struct kvm_s390_interrupt *
|
|
see also: include/linux/kvm.h
|
|
This ioctl is used to submit an interrupt for a specific virtual cpu.
|
|
Only some interrupt types defined in include/linux/kvm.h make sense when
|
|
submitted for a specific cpu. The following interrupts are not considered
|
|
to be useful, and a call to inject them will result in -EINVAL error code:
|
|
service processor calls and virtio interrupts. Valid interrupt types are:
|
|
KVM_S390_PROGRAM_INT
|
|
KVM_S390_SIGP_STOP
|
|
KVM_S390_RESTART
|
|
KVM_S390_SIGP_SET_PREFIX
|
|
KVM_S390_INT_EMERGENCY
|
|
|
|
ioctl: KVM_S390_STORE_STATUS
|
|
args: unsigned long
|
|
see also: include/linux/kvm.h
|
|
This ioctl stores the state of the cpu at the guest real address given as
|
|
argument, unless one of the following values defined in include/linux/kvm.h
|
|
is given as argument:
|
|
KVM_S390_STORE_STATUS_NOADDR - the CPU stores its status to the save area in
|
|
absolute lowcore as defined by the principles of operation
|
|
KVM_S390_STORE_STATUS_PREFIXED - the CPU stores its status to the save area in
|
|
its prefix page just like the dump tool that comes with zipl. This is useful
|
|
to create a system dump for use with lkcdutils or crash.
|
|
|
|
ioctl: KVM_S390_SET_INITIAL_PSW
|
|
args: struct kvm_s390_psw *
|
|
see also: include/linux/kvm.h
|
|
This ioctl can be used to set the processor status word (psw) of a stopped cpu
|
|
prior to running it with KVM_RUN. Note that this call is not required to modify
|
|
the psw during sie intercepts that fall back to userspace because struct kvm_run
|
|
does contain the psw, and this value is evaluated during reentry of KVM_RUN
|
|
after the intercept exit was recognized.
|
|
|
|
ioctl: KVM_S390_INITIAL_RESET
|
|
args: none
|
|
see also: include/linux/kvm.h
|
|
This ioctl can be used to perform an initial cpu reset as defined by the
|
|
principles of operation. The target cpu has to be in stopped state.
|