From ccc7910fe564d99415def7c041fa261e62a43011 Mon Sep 17 00:00:00 2001 From: Carsten Otte Date: Wed, 4 Jan 2012 10:25:26 +0100 Subject: KVM: s390: ucontrol: interface to inject faults on a vcpu page table This patch allows the user to fault in pages on a virtual cpus address space for user controlled virtual machines. Typically this is superfluous because userspace can just create a mapping and let the kernel's page fault logic take are of it. There is one exception: SIE won't start if the lowcore is not present. Normally the kernel takes care of this [handle_validity() in arch/s390/kvm/intercept.c] but since the kernel does not handle intercepts for user controlled virtual machines, userspace needs to be able to handle this condition. Signed-off-by: Carsten Otte Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- Documentation/virtual/kvm/api.txt | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'Documentation/virtual') diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 5ebf47d99e56..a67fb35993fa 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1539,6 +1539,22 @@ This ioctl unmaps the memory in the vcpu's address space starting at "vcpu_addr" with the length "length". The field "user_addr" is ignored. All parameters need to be alligned by 1 megabyte. +4.66 KVM_S390_VCPU_FAULT + +Capability: KVM_CAP_S390_UCONTROL +Architectures: s390 +Type: vcpu ioctl +Parameters: vcpu absolute address (in) +Returns: 0 in case of success + +This call creates a page table entry on the virtual cpu's address space +(for user controlled virtual machines) or the virtual machine's address +space (for regular virtual machines). This only works for minor faults, +thus it's recommended to access subject memory page via the user page +table upfront. This is useful to handle validity intercepts for user +controlled virtual machines to fault in the virtual cpu's lowcore pages +prior to calling the KVM_RUN ioctl. + 5. The kvm_run structure Application code obtains a pointer to the kvm_run structure by -- cgit v1.2.3