docs: kvm: convert devices/vm.txt to ReST

- Use title markups;
- adjust indentation and add blank lines as needed;
- use :field: markups;
- Use cross-references;
- mark code blocks as such.
Signed-off-by: NMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: NCornelia Huck <cohuck@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Documentation/virt/kvm/devices/index.rst

@@ -14,3 +14,4 @@ Devices
    s390_flic
    vcpu
    vfio
+   vm

Documentation/virt/kvm/devices/vm.txt → Documentation/virt/kvm/devices/vm.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+====================
 Generic vm interface
-====================================
+====================
 
 The virtual machine "device" also accepts the ioctls KVM_SET_DEVICE_ATTR,
 KVM_GET_DEVICE_ATTR, and KVM_HAS_DEVICE_ATTR. The interface uses the same
@@ -10,30 +13,38 @@ The groups and attributes per virtual machine, if any, are architecture
 specific.
 
 1. GROUP: KVM_S390_VM_MEM_CTRL
-Architectures: s390
+==============================
+
+:Architectures: s390
 
 1.1. ATTRIBUTE: KVM_S390_VM_MEM_ENABLE_CMMA
-Parameters: none
-Returns: -EBUSY if a vcpu is already defined, otherwise 0
+-------------------------------------------
+
+:Parameters: none
+:Returns: -EBUSY if a vcpu is already defined, otherwise 0
 
 Enables Collaborative Memory Management Assist (CMMA) for the virtual machine.
 
 1.2. ATTRIBUTE: KVM_S390_VM_MEM_CLR_CMMA
-Parameters: none
-Returns: -EINVAL if CMMA was not enabled
-         0 otherwise
+----------------------------------------
+
+:Parameters: none
+:Returns: -EINVAL if CMMA was not enabled;
+	  0 otherwise
 
 Clear the CMMA status for all guest pages, so any pages the guest marked
 as unused are again used any may not be reclaimed by the host.
 
 1.3. ATTRIBUTE KVM_S390_VM_MEM_LIMIT_SIZE
-Parameters: in attr->addr the address for the new limit of guest memory
-Returns: -EFAULT if the given address is not accessible
-         -EINVAL if the virtual machine is of type UCONTROL
-         -E2BIG if the given guest memory is to big for that machine
-         -EBUSY if a vcpu is already defined
-         -ENOMEM if not enough memory is available for a new shadow guest mapping
-          0 otherwise
+-----------------------------------------
+
+:Parameters: in attr->addr the address for the new limit of guest memory
+:Returns: -EFAULT if the given address is not accessible;
+	  -EINVAL if the virtual machine is of type UCONTROL;
+	  -E2BIG if the given guest memory is to big for that machine;
+	  -EBUSY if a vcpu is already defined;
+	  -ENOMEM if not enough memory is available for a new shadow guest mapping;
+	  0 otherwise.
 
 Allows userspace to query the actual limit and set a new limit for
 the maximum guest memory size. The limit will be rounded up to
@@ -42,78 +53,92 @@ the number of page table levels. In the case that there is no limit we will set
 the limit to KVM_S390_NO_MEM_LIMIT (U64_MAX).
 
 2. GROUP: KVM_S390_VM_CPU_MODEL
-Architectures: s390
+===============================
+
+:Architectures: s390
 
 2.1. ATTRIBUTE: KVM_S390_VM_CPU_MACHINE (r/o)
+---------------------------------------------
 
-Allows user space to retrieve machine and kvm specific cpu related information:
+Allows user space to retrieve machine and kvm specific cpu related information::
 
-struct kvm_s390_vm_cpu_machine {
+  struct kvm_s390_vm_cpu_machine {
        __u64 cpuid;           # CPUID of host
        __u32 ibc;             # IBC level range offered by host
        __u8  pad[4];
        __u64 fac_mask[256];   # set of cpu facilities enabled by KVM
        __u64 fac_list[256];   # set of cpu facilities offered by host
-}
+  }
 
-Parameters: address of buffer to store the machine related cpu data
-            of type struct kvm_s390_vm_cpu_machine*
-Returns:    -EFAULT if the given address is not accessible from kernel space
-	    -ENOMEM if not enough memory is available to process the ioctl
-	    0 in case of success
+:Parameters: address of buffer to store the machine related cpu data
+	     of type struct kvm_s390_vm_cpu_machine*
+:Returns:   -EFAULT if the given address is not accessible from kernel space;
+	    -ENOMEM if not enough memory is available to process the ioctl;
+	    0 in case of success.
 
 2.2. ATTRIBUTE: KVM_S390_VM_CPU_PROCESSOR (r/w)
+===============================================
 
-Allows user space to retrieve or request to change cpu related information for a vcpu:
+Allows user space to retrieve or request to change cpu related information for a vcpu::
 
-struct kvm_s390_vm_cpu_processor {
+  struct kvm_s390_vm_cpu_processor {
        __u64 cpuid;           # CPUID currently (to be) used by this vcpu
        __u16 ibc;             # IBC level currently (to be) used by this vcpu
        __u8  pad[6];
        __u64 fac_list[256];   # set of cpu facilities currently (to be) used
-                              # by this vcpu
-}
+			      # by this vcpu
+  }
 
 KVM does not enforce or limit the cpu model data in any form. Take the information
 retrieved by means of KVM_S390_VM_CPU_MACHINE as hint for reasonable configuration
 setups. Instruction interceptions triggered by additionally set facility bits that
 are not handled by KVM need to by imlemented in the VM driver code.
 
-Parameters: address of buffer to store/set the processor related cpu
-	    data of type struct kvm_s390_vm_cpu_processor*.
-Returns:    -EBUSY in case 1 or more vcpus are already activated (only in write case)
-	    -EFAULT if the given address is not accessible from kernel space
-	    -ENOMEM if not enough memory is available to process the ioctl
-	    0 in case of success
+:Parameters: address of buffer to store/set the processor related cpu
+	     data of type struct kvm_s390_vm_cpu_processor*.
+:Returns:  -EBUSY in case 1 or more vcpus are already activated (only in write case);
+	   -EFAULT if the given address is not accessible from kernel space;
+	   -ENOMEM if not enough memory is available to process the ioctl;
+	   0 in case of success.
+
+.. _KVM_S390_VM_CPU_MACHINE_FEAT:
 
 2.3. ATTRIBUTE: KVM_S390_VM_CPU_MACHINE_FEAT (r/o)
+--------------------------------------------------
 
 Allows user space to retrieve available cpu features. A feature is available if
 provided by the hardware and supported by kvm. In theory, cpu features could
 even be completely emulated by kvm.
 
-struct kvm_s390_vm_cpu_feat {
-        __u64 feat[16]; # Bitmap (1 = feature available), MSB 0 bit numbering
-};
+::
 
-Parameters: address of a buffer to load the feature list from.
-Returns:    -EFAULT if the given address is not accessible from kernel space.
-	    0 in case of success.
+  struct kvm_s390_vm_cpu_feat {
+	__u64 feat[16]; # Bitmap (1 = feature available), MSB 0 bit numbering
+  };
+
+:Parameters: address of a buffer to load the feature list from.
+:Returns:  -EFAULT if the given address is not accessible from kernel space;
+	   0 in case of success.
 
 2.4. ATTRIBUTE: KVM_S390_VM_CPU_PROCESSOR_FEAT (r/w)
+----------------------------------------------------
 
 Allows user space to retrieve or change enabled cpu features for all VCPUs of a
 VM. Features that are not available cannot be enabled.
 
-See 2.3. for a description of the parameter struct.
+See :ref:`KVM_S390_VM_CPU_MACHINE_FEAT` for
+a description of the parameter struct.
 
-Parameters: address of a buffer to store/load the feature list from.
-Returns:    -EFAULT if the given address is not accessible from kernel space.
-	    -EINVAL if a cpu feature that is not available is to be enabled.
-	    -EBUSY if at least one VCPU has already been defined.
+:Parameters: address of a buffer to store/load the feature list from.
+:Returns:   -EFAULT if the given address is not accessible from kernel space;
+	    -EINVAL if a cpu feature that is not available is to be enabled;
+	    -EBUSY if at least one VCPU has already been defined;
 	    0 in case of success.
 
+.. _KVM_S390_VM_CPU_MACHINE_SUBFUNC:
+
 2.5. ATTRIBUTE: KVM_S390_VM_CPU_MACHINE_SUBFUNC (r/o)
+-----------------------------------------------------
 
 Allows user space to retrieve available cpu subfunctions without any filtering
 done by a set IBC. These subfunctions are indicated to the guest VCPU via
@@ -126,7 +151,9 @@ contained in the returned struct. If the affected instruction
 indicates subfunctions via a "test bit" mechanism, the subfunction codes are
 contained in the returned struct in MSB 0 bit numbering.
 
-struct kvm_s390_vm_cpu_subfunc {
+::
+
+  struct kvm_s390_vm_cpu_subfunc {
        u8 plo[32];           # always valid (ESA/390 feature)
        u8 ptff[16];          # valid with TOD-clock steering
        u8 kmac[16];          # valid with Message-Security-Assist
@@ -143,13 +170,14 @@ struct kvm_s390_vm_cpu_subfunc {
        u8 kma[16];           # valid with Message-Security-Assist-Extension 8
        u8 kdsa[16];          # valid with Message-Security-Assist-Extension 9
        u8 reserved[1792];    # reserved for future instructions
-};
+  };
 
-Parameters: address of a buffer to load the subfunction blocks from.
-Returns:    -EFAULT if the given address is not accessible from kernel space.
+:Parameters: address of a buffer to load the subfunction blocks from.
+:Returns:   -EFAULT if the given address is not accessible from kernel space;
 	    0 in case of success.
 
 2.6. ATTRIBUTE: KVM_S390_VM_CPU_PROCESSOR_SUBFUNC (r/w)
+-------------------------------------------------------
 
 Allows user space to retrieve or change cpu subfunctions to be indicated for
 all VCPUs of a VM. This attribute will only be available if kernel and
@@ -164,107 +192,125 @@ As long as no data has been written, a read will fail. The IBC will be used
 to determine available subfunctions in this case, this will guarantee backward
 compatibility.
 
-See 2.5. for a description of the parameter struct.
+See :ref:`KVM_S390_VM_CPU_MACHINE_SUBFUNC` for a
+description of the parameter struct.
 
-Parameters: address of a buffer to store/load the subfunction blocks from.
-Returns:    -EFAULT if the given address is not accessible from kernel space.
-	    -EINVAL when reading, if there was no write yet.
-	    -EBUSY if at least one VCPU has already been defined.
+:Parameters: address of a buffer to store/load the subfunction blocks from.
+:Returns:   -EFAULT if the given address is not accessible from kernel space;
+	    -EINVAL when reading, if there was no write yet;
+	    -EBUSY if at least one VCPU has already been defined;
 	    0 in case of success.
 
 3. GROUP: KVM_S390_VM_TOD
-Architectures: s390
+=========================
+
+:Architectures: s390
 
 3.1. ATTRIBUTE: KVM_S390_VM_TOD_HIGH
+------------------------------------
 
 Allows user space to set/get the TOD clock extension (u8) (superseded by
 KVM_S390_VM_TOD_EXT).
 
-Parameters: address of a buffer in user space to store the data (u8) to
-Returns:    -EFAULT if the given address is not accessible from kernel space
+:Parameters: address of a buffer in user space to store the data (u8) to
+:Returns:   -EFAULT if the given address is not accessible from kernel space;
 	    -EINVAL if setting the TOD clock extension to != 0 is not supported
 
 3.2. ATTRIBUTE: KVM_S390_VM_TOD_LOW
+-----------------------------------
 
 Allows user space to set/get bits 0-63 of the TOD clock register as defined in
 the POP (u64).
 
-Parameters: address of a buffer in user space to store the data (u64) to
-Returns:    -EFAULT if the given address is not accessible from kernel space
+:Parameters: address of a buffer in user space to store the data (u64) to
+:Returns:    -EFAULT if the given address is not accessible from kernel space
 
 3.3. ATTRIBUTE: KVM_S390_VM_TOD_EXT
+-----------------------------------
+
 Allows user space to set/get bits 0-63 of the TOD clock register as defined in
 the POP (u64). If the guest CPU model supports the TOD clock extension (u8), it
 also allows user space to get/set it. If the guest CPU model does not support
 it, it is stored as 0 and not allowed to be set to a value != 0.
 
-Parameters: address of a buffer in user space to store the data
-            (kvm_s390_vm_tod_clock) to
-Returns:    -EFAULT if the given address is not accessible from kernel space
+:Parameters: address of a buffer in user space to store the data
+	     (kvm_s390_vm_tod_clock) to
+:Returns:   -EFAULT if the given address is not accessible from kernel space;
 	    -EINVAL if setting the TOD clock extension to != 0 is not supported
 
 4. GROUP: KVM_S390_VM_CRYPTO
-Architectures: s390
+============================
+
+:Architectures: s390
 
 4.1. ATTRIBUTE: KVM_S390_VM_CRYPTO_ENABLE_AES_KW (w/o)
+------------------------------------------------------
 
 Allows user space to enable aes key wrapping, including generating a new
 wrapping key.
 
-Parameters: none
-Returns:    0
+:Parameters: none
+:Returns:    0
 
 4.2. ATTRIBUTE: KVM_S390_VM_CRYPTO_ENABLE_DEA_KW (w/o)
+------------------------------------------------------
 
 Allows user space to enable dea key wrapping, including generating a new
 wrapping key.
 
-Parameters: none
-Returns:    0
+:Parameters: none
+:Returns:    0
 
 4.3. ATTRIBUTE: KVM_S390_VM_CRYPTO_DISABLE_AES_KW (w/o)
+-------------------------------------------------------
 
 Allows user space to disable aes key wrapping, clearing the wrapping key.
 
-Parameters: none
-Returns:    0
+:Parameters: none
+:Returns:    0
 
 4.4. ATTRIBUTE: KVM_S390_VM_CRYPTO_DISABLE_DEA_KW (w/o)
+-------------------------------------------------------
 
 Allows user space to disable dea key wrapping, clearing the wrapping key.
 
-Parameters: none
-Returns:    0
+:Parameters: none
+:Returns:    0
 
 5. GROUP: KVM_S390_VM_MIGRATION
-Architectures: s390
+===============================
+
+:Architectures: s390
 
 5.1. ATTRIBUTE: KVM_S390_VM_MIGRATION_STOP (w/o)
+------------------------------------------------
 
 Allows userspace to stop migration mode, needed for PGSTE migration.
 Setting this attribute when migration mode is not active will have no
 effects.
 
-Parameters: none
-Returns:    0
+:Parameters: none
+:Returns:    0
 
 5.2. ATTRIBUTE: KVM_S390_VM_MIGRATION_START (w/o)
+-------------------------------------------------
 
 Allows userspace to start migration mode, needed for PGSTE migration.
 Setting this attribute when migration mode is already active will have
 no effects.
 
-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)
+: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);
 	    0 in case of success.
 
 5.3. ATTRIBUTE: KVM_S390_VM_MIGRATION_STATUS (r/o)
+--------------------------------------------------
 
 Allows userspace to query the status of migration mode.
 
-Parameters: address of a buffer in user space to store the data (u64) to;
-	    the data itself is either 0 if migration mode is disabled or 1
-	    if it is enabled
-Returns:    -EFAULT if the given address is not accessible from kernel space
+:Parameters: address of a buffer in user space to store the data (u64) to;
+	     the data itself is either 0 if migration mode is disabled or 1
+	     if it is enabled
+:Returns:   -EFAULT if the given address is not accessible from kernel space;
 	    0 in case of success.