diff options
Diffstat (limited to 'Documentation/virt')
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 46 | ||||
| -rw-r--r-- | Documentation/virt/kvm/devices/vm.rst | 4 |
2 files changed, 41 insertions, 9 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 1b1f721e3fd9..62de0768d6aa 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -3736,7 +3736,7 @@ The fields in each entry are defined as follows: :Parameters: struct kvm_s390_mem_op (in) :Returns: = 0 on success, < 0 on generic error (e.g. -EFAULT or -ENOMEM), - > 0 if an exception occurred while walking the page tables + 16 bit program exception code if the access causes such an exception Read or write data from/to the VM's memory. The KVM_CAP_S390_MEM_OP_EXTENSION capability specifies what functionality is @@ -3754,6 +3754,8 @@ Parameters are specified via the following structure:: struct { __u8 ar; /* the access register number */ __u8 key; /* access key, ignored if flag unset */ + __u8 pad1[6]; /* ignored */ + __u64 old_addr; /* ignored if flag unset */ }; __u32 sida_offset; /* offset into the sida */ __u8 reserved[32]; /* ignored */ @@ -3781,6 +3783,7 @@ Possible operations are: * ``KVM_S390_MEMOP_ABSOLUTE_WRITE`` * ``KVM_S390_MEMOP_SIDA_READ`` * ``KVM_S390_MEMOP_SIDA_WRITE`` + * ``KVM_S390_MEMOP_ABSOLUTE_CMPXCHG`` Logical read/write: ^^^^^^^^^^^^^^^^^^^ @@ -3829,7 +3832,7 @@ the checks required for storage key protection as one operation (as opposed to user space getting the storage keys, performing the checks, and accessing memory thereafter, which could lead to a delay between check and access). Absolute accesses are permitted for the VM ioctl if KVM_CAP_S390_MEM_OP_EXTENSION -is > 0. +has the KVM_S390_MEMOP_EXTENSION_CAP_BASE bit set. Currently absolute accesses are not permitted for VCPU ioctls. Absolute accesses are permitted for non-protected guests only. @@ -3837,7 +3840,26 @@ Supported flags: * ``KVM_S390_MEMOP_F_CHECK_ONLY`` * ``KVM_S390_MEMOP_F_SKEY_PROTECTION`` -The semantics of the flags are as for logical accesses. +The semantics of the flags common with logical accesses are as for logical +accesses. + +Absolute cmpxchg: +^^^^^^^^^^^^^^^^^ + +Perform cmpxchg on absolute guest memory. Intended for use with the +KVM_S390_MEMOP_F_SKEY_PROTECTION flag. +Instead of doing an unconditional write, the access occurs only if the target +location contains the value pointed to by "old_addr". +This is performed as an atomic cmpxchg with the length specified by the "size" +parameter. "size" must be a power of two up to and including 16. +If the exchange did not take place because the target value doesn't match the +old value, the value "old_addr" points to is replaced by the target value. +User space can tell if an exchange took place by checking if this replacement +occurred. The cmpxchg op is permitted for the VM ioctl if +KVM_CAP_S390_MEM_OP_EXTENSION has flag KVM_S390_MEMOP_EXTENSION_CAP_CMPXCHG set. + +Supported flags: + * ``KVM_S390_MEMOP_F_SKEY_PROTECTION`` SIDA read/write: ^^^^^^^^^^^^^^^^ @@ -4457,6 +4479,18 @@ not holding a previously reported uncorrected error). :Parameters: struct kvm_s390_cmma_log (in, out) :Returns: 0 on success, a negative value on error +Errors: + + ====== ============================================================= + ENOMEM not enough memory can be allocated to complete the task + ENXIO if CMMA is not enabled + EINVAL if KVM_S390_CMMA_PEEK is not set but migration mode was not enabled + EINVAL if KVM_S390_CMMA_PEEK is not set but dirty tracking has been + disabled (and thus migration mode was automatically disabled) + EFAULT if the userspace address is invalid or if no page table is + present for the addresses (e.g. when using hugepages). + ====== ============================================================= + This ioctl is used to get the values of the CMMA bits on the s390 architecture. It is meant to be used in two scenarios: @@ -4537,12 +4571,6 @@ mask is unused. values points to the userspace buffer where the result will be stored. -This ioctl can fail with -ENOMEM if not enough memory can be allocated to -complete the task, with -ENXIO if CMMA is not enabled, with -EINVAL if -KVM_S390_CMMA_PEEK is not set but migration mode was not enabled, with --EFAULT if the userspace address is invalid or if no page table is -present for the addresses (e.g. when using hugepages). - 4.108 KVM_S390_SET_CMMA_BITS ---------------------------- diff --git a/Documentation/virt/kvm/devices/vm.rst b/Documentation/virt/kvm/devices/vm.rst index 60acc39e0e93..147efec626e5 100644 --- a/Documentation/virt/kvm/devices/vm.rst +++ b/Documentation/virt/kvm/devices/vm.rst @@ -302,6 +302,10 @@ Allows userspace to start migration mode, needed for PGSTE migration. Setting this attribute when migration mode is already active will have no effects. +Dirty tracking must be enabled on all memslots, else -EINVAL is returned. When +dirty tracking is disabled on any memslot, migration mode is automatically +stopped. + :Parameters: none :Returns: -ENOMEM if there is not enough free memory to start migration mode; -EINVAL if the state of the VM is invalid (e.g. no memory defined); |