@@ -5034,7 +5034,6 @@ see KVM_XEN_VCPU_SET_ATTR above.
The KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST type may not be used
with the KVM_XEN_VCPU_GET_ATTR ioctl.
-
4.131 KVM_GET_SREGS2
------------------
@@ -5081,6 +5080,195 @@ Writes special registers into the vcpu.
See KVM_GET_SREGS2 for the data structures.
This ioctl (when supported) replaces the KVM_SET_SREGS.
+4.133 KVM_GET_STATS_FD
+----------------------
+
+:Capability: KVM_CAP_STATS_BINARY_FD
+:Architectures: all
+:Type: vm ioctl, vcpu ioctl
+:Parameters: none
+:Returns: statistics file descriptor on success, < 0 on error
+
+Errors:
+
+ ====== ======================================================
+ ENOMEM if the fd could not be created due to lack of memory
+ EMFILE if the number of opened files exceeds the limit
+ ====== ======================================================
+
+The file descriptor can be used to read VM/vCPU statistics data in binary
+format. Please be aware that it is not guaranteed that the four blocks are
+adjacent, that's why offset fields are included in the Header. But the
+order of the four blocks are guaranteed and there is no overlap between any
+two blocks.
+And all four blocks are aligned with 64 bits in the file.
+The file data is organized into three blocks as below:
++-------------+
+| Header |
++-------------+
++-------------+
+| id string |
++-------------+
++-------------+
+| Descriptors |
++-------------+
++-------------+
+| Stats Data |
++-------------+
+
+The Header block is always at the start of the file. It is only needed to be
+read one time for the lifetime of the file descriptor.
+It is in the form of ``struct kvm_stats_header`` as below::
+
+ struct kvm_stats_header {
+ __u32 flags;
+ __u32 name_size;
+ __u32 num_desc;
+ __u32 id_offset;
+ __u32 desc_offset;
+ __u32 data_offset;
+ };
+
+The ``flags`` field is not used at the moment. It is always read as 0.
+
+The ``name_size`` field is the size (in byte) of the statistics name string
+(including trailing '\0') appended to the end of every statistics descriptor.
+It also is the size of id string block.
+
+The ``num_desc`` field is the number of statistics.
+
+The ``id_offset`` field is the offset of the id string from the start of the
+file indicated by the file descriptor. It is a multiple of 8.
+
+The ``desc_offset`` field is the offset of the Descriptors block from the start
+of the file indicated by the file descriptor. It is a multiple of 8.
+
+The ``data_offset`` field is the offset of the Stats Data block from the start
+of the file indicated by the file descriptor. It is a multiple of 8.
+
+The id string is a '\0' terminated string which identifies the corresponding
+KVM statistics. For VM statistics, it is in the form of "kvm-{kvm pid}", like
+"kvm-12345". For VCPU statistics, it is in the form of
+"kvm-{kvm pid}/vcpu-{vcpu id}", like "kvm-12345/vcpu-12".
+The size of id string block is indicated by the ``name_size`` field in Header.
+
+The Descriptors block is only needed to be read once for the lifetime of the
+file descriptor. It is an array of ``struct kvm_stats_desc`` as shown in
+below code block::
+
+ #define KVM_STATS_TYPE_SHIFT 0
+ #define KVM_STATS_TYPE_MASK (0xF << KVM_STATS_TYPE_SHIFT)
+ #define KVM_STATS_TYPE_CUMULATIVE (0x0 << KVM_STATS_TYPE_SHIFT)
+ #define KVM_STATS_TYPE_INSTANT (0x1 << KVM_STATS_TYPE_SHIFT)
+ #define KVM_STATS_TYPE_PEAK (0x2 << KVM_STATS_TYPE_SHIFT)
+ #define KVM_STATS_TYPE_MAX KVM_STATS_TYPE_PEAK
+
+ #define KVM_STATS_UNIT_SHIFT 4
+ #define KVM_STATS_UNIT_MASK (0xF << KVM_STATS_UNIT_SHIFT)
+ #define KVM_STATS_UNIT_NONE (0x0 << KVM_STATS_UNIT_SHIFT)
+ #define KVM_STATS_UNIT_BYTES (0x1 << KVM_STATS_UNIT_SHIFT)
+ #define KVM_STATS_UNIT_SECONDS (0x2 << KVM_STATS_UNIT_SHIFT)
+ #define KVM_STATS_UNIT_CYCLES (0x3 << KVM_STATS_UNIT_SHIFT)
+ #define KVM_STATS_UNIT_MAX KVM_STATS_UNIT_CYCLES
+
+ #define KVM_STATS_BASE_SHIFT 8
+ #define KVM_STATS_BASE_MASK (0xF << KVM_STATS_BASE_SHIFT)
+ #define KVM_STATS_BASE_POW10 (0x0 << KVM_STATS_BASE_SHIFT)
+ #define KVM_STATS_BASE_POW2 (0x1 << KVM_STATS_BASE_SHIFT)
+ #define KVM_STATS_BASE_MAX KVM_STATS_BASE_POW2
+
+ struct kvm_stats_desc {
+ __u32 flags;
+ __s16 exponent;
+ __u16 size;
+ __u32 offset;
+ __u32 unused;
+ char name[];
+ };
+
+The ``flags`` field contains the type and unit of the statistics data described
+by this descriptor. Its endianness is CPU native.
+The following flags are supported:
+
+Bits 0-3 of ``flags`` encode the type:
+ * ``KVM_STATS_TYPE_CUMULATIVE``
+ The statistics data is cumulative. The value of data can only be increased.
+ Most of the counters used in KVM are of this type.
+ The corresponding ``size`` field for this type is always 1.
+ All cumulative statistics data are read/write.
+ * ``KVM_STATS_TYPE_INSTANT``
+ The statistics data is instantaneous. Its value can be increased or
+ decreased. This type is usually used as a measurement of some resources,
+ like the number of dirty pages, the number of large pages, etc.
+ All instant statistics are read only.
+ The corresponding ``size`` field for this type is always 1.
+ * ``KVM_STATS_TYPE_PEAK``
+ The statistics data is peak, which is used as read/write instant statistics.
+ The corresponding ``size`` field for this type is always 1.
+
+Bits 4-7 of ``flags`` encode the unit:
+ * ``KVM_STATS_UNIT_NONE``
+ There is no unit for the value of statistics data. This usually means that
+ the value is a simple counter of an event.
+ * ``KVM_STATS_UNIT_BYTES``
+ It indicates that the statistics data is used to measure memory size, in the
+ unit of Byte, KiByte, MiByte, GiByte, etc. The unit of the data is
+ determined by the ``exponent`` field in the descriptor. The
+ ``KVM_STATS_BASE_POW2`` flag is valid in this case. The unit of the data is
+ determined by ``pow(2, exponent)``. For example, if value is 10,
+ ``exponent`` is 20, which means the unit of statistics data is MiByte, we
+ can get the statistics data in the unit of Byte by
+ ``value * pow(2, exponent) = 10 * pow(2, 20) = 10 MiByte`` which is
+ 10 * 1024 * 1024 Bytes.
+ * ``KVM_STATS_UNIT_SECONDS``
+ It indicates that the statistics data is used to measure time/latency, in
+ the unit of nanosecond, microsecond, millisecond and second. The unit of the
+ data is determined by the ``exponent`` field in the descriptor. The
+ ``KVM_STATS_BASE_POW10`` flag is valid in this case. The unit of the data
+ is determined by ``pow(10, exponent)``. For example, if value is 2000000,
+ ``exponent`` is -6, which means the unit of statistics data is microsecond,
+ we can get the statistics data in the unit of second by
+ ``value * pow(10, exponent) = 2000000 * pow(10, -6) = 2 seconds``.
+ * ``KVM_STATS_UNIT_CYCLES``
+ It indicates that the statistics data is used to measure CPU clock cycles.
+ The ``KVM_STATS_BASE_POW10`` flag is valid in this case. For example, if
+ value is 200, ``exponent`` is 4, we can get the number of CPU clock cycles
+ by ``value * pow(10, exponent) = 200 * pow(10, 4) = 2000000``.
+
+Bits 8-11 of ``flags`` encode the base:
+ * ``KVM_STATS_BASE_POW10``
+ The scale is based on power of 10. It is used for measurement of time and
+ CPU clock cycles.
+ * ``KVM_STATS_BASE_POW2``
+ The scale is based on power of 2. It is used for measurement of memory size.
+
+The ``exponent`` field is the scale of corresponding statistics data. For
+example, if the unit is ``KVM_STATS_UNIT_BYTES``, the base is
+``KVM_STATS_BASE_POW2``, the ``exponent`` is 10, then we know that the real
+unit of the statistics data is KBytes a.k.a pow(2, 10) = 1024 bytes.
+If the unit is ``KVM_STATS_UNIT_SECONDS``, the base is ``KVM_STATS_BASE_POW10``,
+the ``exponent`` is -6, then we know that the real unit of the statistics data
+is microsecond a.k.a 1 second * pow(10, -6) = 1 microsecond.
+
+The ``size`` field is the number of values of this statistics data. Its
+value is usually 1 for most of simple statistics. 1 means it contains an
+unsigned 64bit data.
+
+The ``offset`` field is the offset from the start of Data Block to the start of
+the corresponding statistics data.
+
+The ``unused`` fields are reserved for future support for other types of
+statistics data, like log/linear histogram. Its current value is always 0.
+
+The ``name`` field is the name string of the statistics data. The name string
+starts at the end of ``struct kvm_stats_desc``.
+The maximum length (including trailing '\0') is indicated by ``name_size``
+in ``struct kvm_stats_header``.
+
+The Stats Data block contains an array of statistics data whose type is __u64.
+It would be read out by userspace periodically.
+The order of data value in Stats Data block is the same as the order of
+descriptors in Descriptors block.
5. The kvm_run structure
========================
@@ -6969,3 +7157,11 @@ The argument to KVM_ENABLE_CAP is also a bitmask, and must be a subset
of the result of KVM_CHECK_EXTENSION. KVM will forward to userspace
the hypercalls whose corresponding bit is in the argument, and return
ENOSYS for the others.
+
+8.35 KVM_CAP_STATS_BINARY_FD
+----------------------------
+
+:Architectures: all
+
+This capability indicates the feature that userspace can create get a file
+descriptor for every VM and VCPU to read statistics data in binary format.