diff mbox series

[RFC,2/4] KVM: stats: Define APIs for aggregated stats retrieval in binary format

Message ID 20210310003024.2026253-3-jingzhangos@google.com
State Not Applicable
Headers show
Series [RFC,1/4] KVM: stats: Separate statistics name strings from debugfs code | expand

Commit Message

Jing Zhang March 10, 2021, 12:30 a.m. UTC
Define ioctl commands for VM/vCPU aggregated statistics data retrieval
in binary format and update corresponding API documentation.

The capability and ioctl are not enabled for now.
No functional change intended.

Signed-off-by: Jing Zhang <jingzhangos@google.com>
---
 Documentation/virt/kvm/api.rst | 79 ++++++++++++++++++++++++++++++++++
 include/linux/kvm_host.h       |  1 -
 include/uapi/linux/kvm.h       | 60 ++++++++++++++++++++++++++
 3 files changed, 139 insertions(+), 1 deletion(-)

Comments

Marc Zyngier March 10, 2021, 2:58 p.m. UTC | #1
On Wed, 10 Mar 2021 00:30:22 +0000,
Jing Zhang <jingzhangos@google.com> wrote:
> 
> Define ioctl commands for VM/vCPU aggregated statistics data retrieval
> in binary format and update corresponding API documentation.
> 
> The capability and ioctl are not enabled for now.
> No functional change intended.
> 
> Signed-off-by: Jing Zhang <jingzhangos@google.com>
> ---
>  Documentation/virt/kvm/api.rst | 79 ++++++++++++++++++++++++++++++++++
>  include/linux/kvm_host.h       |  1 -
>  include/uapi/linux/kvm.h       | 60 ++++++++++++++++++++++++++
>  3 files changed, 139 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index 1a2b5210cdbf..aa4b5270c966 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -4938,6 +4938,76 @@ 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_STATS_GET_INFO
> +------------------------
> +
> +:Capability: KVM_CAP_STATS_BINARY_FORM
> +:Architectures: all
> +:Type: vm ioctl, vcpu ioctl
> +:Parameters: struct kvm_stats_info (out)
> +:Returns: 0 on success, < 0 on error


Missing description of the errors (this is throughout the document).

> +
> +::
> +
> +  struct kvm_stats_info {
> +        __u32 num_stats;
> +  };
> +
> +This ioctl is used to get the information about VM or vCPU statistics data.
> +The number of statistics data would be returned in field num_stats in
> +struct kvm_stats_info. This ioctl only needs to be called once on running
> +VMs on the same architecture.

Is this allowed to be variable across VMs? Or is that a constant for a
given host system boot?

Given that this returns a single field, is there any value in copying
this structure across? Could it be returned by the ioctl itself
instead, at the expense of only being a 31bit value?

> +
> +4.132 KVM_STATS_GET_NAMES
> +-------------------------
> +
> +:Capability: KVM_CAP_STATS_BINARY_FORM
> +:Architectures: all
> +:Type: vm ioctl, vcpu ioctl
> +:Parameters: struct kvm_stats_names (in/out)
> +:Returns: 0 on success, < 0 on error
> +
> +::
> +
> +  #define KVM_STATS_NAME_LEN		32
> +  struct kvm_stats_names {
> +	__u32 size;
> +	__u8  names[0];
> +  };
> +
> +This ioctl is used to get the string names of all the statistics data for VM
> +or vCPU. Users must use KVM_STATS_GET_INFO to find the number of statistics.
> +They must allocate a buffer of the size num_stats * KVM_STATS_NAME_LEN
> +immediately following struct kvm_stats_names. The size field of kvm_stats_name
> +must contain the buffer size as an input.

What is the unit for the buffer size? bytes? or number of "names"?

> +The buffer can be treated like a string array, each name string is null-padded
> +to a size of KVM_STATS_NAME_LEN;

Is this allowed to query fewer strings than described by
kvm_stats_info? If it isn't, I question the need for the "size"
field. Either there is enough space in the buffer passed by userspace,
or -EFAULT is returned.

> +This ioclt only needs to be called once on running VMs on the same architecture.

Same question about the immutability of these names.

> +
> +4.133 KVM_STATS_GET_DATA
> +-------------------------
> +
> +:Capability: KVM_CAP_STATS_BINARY_FORM
> +:Architectures: all
> +:Type: vm ioctl, vcpu ioctl
> +:Parameters: struct kvm_stats_data (in/out)
> +:Returns: 0 on success, < 0 on error
> +
> +::
> +
> +  struct kvm_stats_data {
> +	__u32 size;

Same question about the actual need for this field.

> +	__u64 data[0];

So userspace always sees a 64bit quantify per stat. My earlier comment
about the ulong/u64 discrepancy stands! ;-)

> +  };
> +
> +This ioctl is used to get the aggregated statistics data for VM or vCPU.
> +Users must use KVM_STATS_GET_INFO to find the number of statistics.
> +They must allocate a buffer of the appropriate size num_stats * sizeof(data[0])
> +immediately following struct kvm_stats_data. The size field of kvm_stats_data
> +must contain the buffer size as an input.
> +The data buffer 1-1 maps to name strings buffer in sequential order.
> +This ioctl is usually called periodically to pull statistics data.

Is there any provision to reset the counters on read?

> +
>  5. The kvm_run structure
>  ========================
>  
> @@ -6721,3 +6791,12 @@ vcpu_info is set.
>  The KVM_XEN_HVM_CONFIG_RUNSTATE flag indicates that the runstate-related
>  features KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR/_CURRENT/_DATA/_ADJUST are
>  supported by the KVM_XEN_VCPU_SET_ATTR/KVM_XEN_VCPU_GET_ATTR ioctls.
> +
> +8.31 KVM_CAP_STATS_BINARY_FORM
> +------------------------------
> +
> +:Architectures: all
> +
> +This capability indicates that KVM supports retrieving aggregated statistics
> +data in binary format with corresponding VM/VCPU ioctl KVM_STATS_GET_INFO,
> +KVM_STATS_GET_NAMES and KVM_STATS_GET_DATA.

nit: for ease of reviewing, consider splitting the documentation in a
separate patch.

> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 1ea297458306..f2dabf457717 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1164,7 +1164,6 @@ static inline bool kvm_is_error_gpa(struct kvm *kvm, gpa_t gpa)
>  
>  #define VM_STAT_COUNT		(sizeof(struct kvm_vm_stat)/sizeof(ulong))
>  #define VCPU_STAT_COUNT		(sizeof(struct kvm_vcpu_stat)/sizeof(u64))
> -#define KVM_STATS_NAME_LEN	32
>  
>  /* Make sure it is synced with fields in struct kvm_vm_stat. */
>  extern const char kvm_vm_stat_strings[][KVM_STATS_NAME_LEN];
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index f6afee209620..ad185d4c5e42 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1078,6 +1078,7 @@ struct kvm_ppc_resize_hpt {
>  #define KVM_CAP_DIRTY_LOG_RING 192
>  #define KVM_CAP_X86_BUS_LOCK_EXIT 193
>  #define KVM_CAP_PPC_DAWR1 194
> +#define KVM_CAP_STATS_BINARY_FORM 195
>  
>  #ifdef KVM_CAP_IRQ_ROUTING
>  
> @@ -1853,4 +1854,63 @@ struct kvm_dirty_gfn {
>  #define KVM_BUS_LOCK_DETECTION_OFF             (1 << 0)
>  #define KVM_BUS_LOCK_DETECTION_EXIT            (1 << 1)
>  
> +/* Available with KVM_CAP_STATS_BINARY_FORM */
> +
> +#define KVM_STATS_NAME_LEN		32
> +
> +/**
> + * struct kvm_stats_info - statistics information
> + *
> + * Used as parameter for ioctl %KVM_STATS_GET_INFO.
> + *
> + * @num_stats: On return, the number of statistics data of vm or vcpu.
> + *
> + */
> +struct kvm_stats_info {
> +	__u32 num_stats;
> +};
> +
> +/**
> + * struct kvm_stats_names - string list of statistics names
> + *
> + * Used as parameter for ioctl %KVM_STATS_GET_NAMES.
> + *
> + * @size: Input from user, indicating the size of buffer after the struture.
> + * @names: Buffer of name string list for vm or vcpu. Each string is
> + *	null-padded to a size of %KVM_STATS_NAME_LEN.
> + *
> + * Users must use %KVM_STATS_GET_INFO to find the number of
> + * statistics. They must allocate a buffer of the appropriate
> + * size (>= &struct kvm_stats_info @num_stats * %KVM_STATS_NAME_LEN)
> + * immediately following this struture.
> + */
> +struct kvm_stats_names {
> +	__u32 size;
> +	__u8  names[0];
> +};
> +
> +/**
> + * struct kvm_stats_data - statistics data array
> + *
> + * Used as parameter for ioctl %KVM_STATS_GET_DATA.
> + *
> + * @size: Input from user, indicating the size of buffer after the struture.
> + * @data: Buffer of statistics data for vm or vcpu.
> + *
> + * Users must use %KVM_STATS_GET_INFO to find the number of
> + * statistics. They must allocate a buffer of the appropriate
> + * size (>= &struct kvm_stats_info @num_stats * sizeof(@data[0])
> + * immediately following this structure.
> + * &struct kvm_stats_names @names 1-1 maps to &structkvm_stats_data
> + * @data in sequential order.
> + */
> +struct kvm_stats_data {
> +	__u32 size;
> +	__u64 data[0];
> +};
> +
> +#define KVM_STATS_GET_INFO		_IOR(KVMIO, 0xcc, struct kvm_stats_info)
> +#define KVM_STATS_GET_NAMES		_IOR(KVMIO, 0xcd, struct kvm_stats_names)
> +#define KVM_STATS_GET_DATA		_IOR(KVMIO, 0xce, struct kvm_stats_data)
> +
>  #endif /* __LINUX_KVM_H */
> -- 
> 2.30.1.766.gb4fecdf3b7-goog
> 
> 

Thanks,

	M.
Jing Zhang March 10, 2021, 7:36 p.m. UTC | #2
Hi Marc,

On Wed, Mar 10, 2021 at 8:58 AM Marc Zyngier <maz@kernel.org> wrote:
>
> On Wed, 10 Mar 2021 00:30:22 +0000,
> Jing Zhang <jingzhangos@google.com> wrote:
> >
> > Define ioctl commands for VM/vCPU aggregated statistics data retrieval
> > in binary format and update corresponding API documentation.
> >
> > The capability and ioctl are not enabled for now.
> > No functional change intended.
> >
> > Signed-off-by: Jing Zhang <jingzhangos@google.com>
> > ---
> >  Documentation/virt/kvm/api.rst | 79 ++++++++++++++++++++++++++++++++++
> >  include/linux/kvm_host.h       |  1 -
> >  include/uapi/linux/kvm.h       | 60 ++++++++++++++++++++++++++
> >  3 files changed, 139 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> > index 1a2b5210cdbf..aa4b5270c966 100644
> > --- a/Documentation/virt/kvm/api.rst
> > +++ b/Documentation/virt/kvm/api.rst
> > @@ -4938,6 +4938,76 @@ 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_STATS_GET_INFO
> > +------------------------
> > +
> > +:Capability: KVM_CAP_STATS_BINARY_FORM
> > +:Architectures: all
> > +:Type: vm ioctl, vcpu ioctl
> > +:Parameters: struct kvm_stats_info (out)
> > +:Returns: 0 on success, < 0 on error
>
>
> Missing description of the errors (this is throughout the document).
Will add errors description.
>
> > +
> > +::
> > +
> > +  struct kvm_stats_info {
> > +        __u32 num_stats;
> > +  };
> > +
> > +This ioctl is used to get the information about VM or vCPU statistics data.
> > +The number of statistics data would be returned in field num_stats in
> > +struct kvm_stats_info. This ioctl only needs to be called once on running
> > +VMs on the same architecture.
>
> Is this allowed to be variable across VMs? Or is that a constant for a
> given host system boot?
It is a constant for a given host system boot.
>
> Given that this returns a single field, is there any value in copying
> this structure across? Could it be returned by the ioctl itself
> instead, at the expense of only being a 31bit value?
It is done in this way for potential information we need in the future.
One candidate is the length of stats names. I am considering to return
the length of name string in this info structure instead of as a constant
exported by uapi, which would be more flexible and put no limit on the
length of stats names.
>
> > +
> > +4.132 KVM_STATS_GET_NAMES
> > +-------------------------
> > +
> > +:Capability: KVM_CAP_STATS_BINARY_FORM
> > +:Architectures: all
> > +:Type: vm ioctl, vcpu ioctl
> > +:Parameters: struct kvm_stats_names (in/out)
> > +:Returns: 0 on success, < 0 on error
> > +
> > +::
> > +
> > +  #define KVM_STATS_NAME_LEN         32
> > +  struct kvm_stats_names {
> > +     __u32 size;
> > +     __u8  names[0];
> > +  };
> > +
> > +This ioctl is used to get the string names of all the statistics data for VM
> > +or vCPU. Users must use KVM_STATS_GET_INFO to find the number of statistics.
> > +They must allocate a buffer of the size num_stats * KVM_STATS_NAME_LEN
> > +immediately following struct kvm_stats_names. The size field of kvm_stats_name
> > +must contain the buffer size as an input.
>
> What is the unit for the buffer size? bytes? or number of "names"?
The unit for the buffer size is bytes. Will clearly indicate the unit.
>
> > +The buffer can be treated like a string array, each name string is null-padded
> > +to a size of KVM_STATS_NAME_LEN;
>
> Is this allowed to query fewer strings than described by
> kvm_stats_info? If it isn't, I question the need for the "size"
> field. Either there is enough space in the buffer passed by userspace,
> or -EFAULT is returned.
It isn't. Will remove the size field.
>
> > +This ioclt only needs to be called once on running VMs on the same architecture.
>
> Same question about the immutability of these names.
The names are immutable for a given system boot.
>
> > +
> > +4.133 KVM_STATS_GET_DATA
> > +-------------------------
> > +
> > +:Capability: KVM_CAP_STATS_BINARY_FORM
> > +:Architectures: all
> > +:Type: vm ioctl, vcpu ioctl
> > +:Parameters: struct kvm_stats_data (in/out)
> > +:Returns: 0 on success, < 0 on error
> > +
> > +::
> > +
> > +  struct kvm_stats_data {
> > +     __u32 size;
>
> Same question about the actual need for this field.
Will remove size field.
>
> > +     __u64 data[0];
>
> So userspace always sees a 64bit quantify per stat. My earlier comment
> about the ulong/u64 discrepancy stands! ;-)
Yes, userspace always sees a 64 bit, but the ulong in KVM would be
64bit or 32bit.
>
> > +  };
> > +
> > +This ioctl is used to get the aggregated statistics data for VM or vCPU.
> > +Users must use KVM_STATS_GET_INFO to find the number of statistics.
> > +They must allocate a buffer of the appropriate size num_stats * sizeof(data[0])
> > +immediately following struct kvm_stats_data. The size field of kvm_stats_data
> > +must contain the buffer size as an input.
> > +The data buffer 1-1 maps to name strings buffer in sequential order.
> > +This ioctl is usually called periodically to pull statistics data.
>
> Is there any provision to reset the counters on read?
Nope.
>
> > +
> >  5. The kvm_run structure
> >  ========================
> >
> > @@ -6721,3 +6791,12 @@ vcpu_info is set.
> >  The KVM_XEN_HVM_CONFIG_RUNSTATE flag indicates that the runstate-related
> >  features KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR/_CURRENT/_DATA/_ADJUST are
> >  supported by the KVM_XEN_VCPU_SET_ATTR/KVM_XEN_VCPU_GET_ATTR ioctls.
> > +
> > +8.31 KVM_CAP_STATS_BINARY_FORM
> > +------------------------------
> > +
> > +:Architectures: all
> > +
> > +This capability indicates that KVM supports retrieving aggregated statistics
> > +data in binary format with corresponding VM/VCPU ioctl KVM_STATS_GET_INFO,
> > +KVM_STATS_GET_NAMES and KVM_STATS_GET_DATA.
>
> nit: for ease of reviewing, consider splitting the documentation in a
> separate patch.
Will do.
>
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index 1ea297458306..f2dabf457717 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -1164,7 +1164,6 @@ static inline bool kvm_is_error_gpa(struct kvm *kvm, gpa_t gpa)
> >
> >  #define VM_STAT_COUNT                (sizeof(struct kvm_vm_stat)/sizeof(ulong))
> >  #define VCPU_STAT_COUNT              (sizeof(struct kvm_vcpu_stat)/sizeof(u64))
> > -#define KVM_STATS_NAME_LEN   32
> >
> >  /* Make sure it is synced with fields in struct kvm_vm_stat. */
> >  extern const char kvm_vm_stat_strings[][KVM_STATS_NAME_LEN];
> > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> > index f6afee209620..ad185d4c5e42 100644
> > --- a/include/uapi/linux/kvm.h
> > +++ b/include/uapi/linux/kvm.h
> > @@ -1078,6 +1078,7 @@ struct kvm_ppc_resize_hpt {
> >  #define KVM_CAP_DIRTY_LOG_RING 192
> >  #define KVM_CAP_X86_BUS_LOCK_EXIT 193
> >  #define KVM_CAP_PPC_DAWR1 194
> > +#define KVM_CAP_STATS_BINARY_FORM 195
> >
> >  #ifdef KVM_CAP_IRQ_ROUTING
> >
> > @@ -1853,4 +1854,63 @@ struct kvm_dirty_gfn {
> >  #define KVM_BUS_LOCK_DETECTION_OFF             (1 << 0)
> >  #define KVM_BUS_LOCK_DETECTION_EXIT            (1 << 1)
> >
> > +/* Available with KVM_CAP_STATS_BINARY_FORM */
> > +
> > +#define KVM_STATS_NAME_LEN           32
> > +
> > +/**
> > + * struct kvm_stats_info - statistics information
> > + *
> > + * Used as parameter for ioctl %KVM_STATS_GET_INFO.
> > + *
> > + * @num_stats: On return, the number of statistics data of vm or vcpu.
> > + *
> > + */
> > +struct kvm_stats_info {
> > +     __u32 num_stats;
> > +};
> > +
> > +/**
> > + * struct kvm_stats_names - string list of statistics names
> > + *
> > + * Used as parameter for ioctl %KVM_STATS_GET_NAMES.
> > + *
> > + * @size: Input from user, indicating the size of buffer after the struture.
> > + * @names: Buffer of name string list for vm or vcpu. Each string is
> > + *   null-padded to a size of %KVM_STATS_NAME_LEN.
> > + *
> > + * Users must use %KVM_STATS_GET_INFO to find the number of
> > + * statistics. They must allocate a buffer of the appropriate
> > + * size (>= &struct kvm_stats_info @num_stats * %KVM_STATS_NAME_LEN)
> > + * immediately following this struture.
> > + */
> > +struct kvm_stats_names {
> > +     __u32 size;
> > +     __u8  names[0];
> > +};
> > +
> > +/**
> > + * struct kvm_stats_data - statistics data array
> > + *
> > + * Used as parameter for ioctl %KVM_STATS_GET_DATA.
> > + *
> > + * @size: Input from user, indicating the size of buffer after the struture.
> > + * @data: Buffer of statistics data for vm or vcpu.
> > + *
> > + * Users must use %KVM_STATS_GET_INFO to find the number of
> > + * statistics. They must allocate a buffer of the appropriate
> > + * size (>= &struct kvm_stats_info @num_stats * sizeof(@data[0])
> > + * immediately following this structure.
> > + * &struct kvm_stats_names @names 1-1 maps to &structkvm_stats_data
> > + * @data in sequential order.
> > + */
> > +struct kvm_stats_data {
> > +     __u32 size;
> > +     __u64 data[0];
> > +};
> > +
> > +#define KVM_STATS_GET_INFO           _IOR(KVMIO, 0xcc, struct kvm_stats_info)
> > +#define KVM_STATS_GET_NAMES          _IOR(KVMIO, 0xcd, struct kvm_stats_names)
> > +#define KVM_STATS_GET_DATA           _IOR(KVMIO, 0xce, struct kvm_stats_data)
> > +
> >  #endif /* __LINUX_KVM_H */
> > --
> > 2.30.1.766.gb4fecdf3b7-goog
> >
> >
>
> Thanks,
>
>         M.
>
> --
> Without deviation from the norm, progress is not possible.

Thanks,
Jing
diff mbox series

Patch

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 1a2b5210cdbf..aa4b5270c966 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4938,6 +4938,76 @@  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_STATS_GET_INFO
+------------------------
+
+:Capability: KVM_CAP_STATS_BINARY_FORM
+:Architectures: all
+:Type: vm ioctl, vcpu ioctl
+:Parameters: struct kvm_stats_info (out)
+:Returns: 0 on success, < 0 on error
+
+::
+
+  struct kvm_stats_info {
+        __u32 num_stats;
+  };
+
+This ioctl is used to get the information about VM or vCPU statistics data.
+The number of statistics data would be returned in field num_stats in
+struct kvm_stats_info. This ioctl only needs to be called once on running
+VMs on the same architecture.
+
+4.132 KVM_STATS_GET_NAMES
+-------------------------
+
+:Capability: KVM_CAP_STATS_BINARY_FORM
+:Architectures: all
+:Type: vm ioctl, vcpu ioctl
+:Parameters: struct kvm_stats_names (in/out)
+:Returns: 0 on success, < 0 on error
+
+::
+
+  #define KVM_STATS_NAME_LEN		32
+  struct kvm_stats_names {
+	__u32 size;
+	__u8  names[0];
+  };
+
+This ioctl is used to get the string names of all the statistics data for VM
+or vCPU. Users must use KVM_STATS_GET_INFO to find the number of statistics.
+They must allocate a buffer of the size num_stats * KVM_STATS_NAME_LEN
+immediately following struct kvm_stats_names. The size field of kvm_stats_name
+must contain the buffer size as an input.
+The buffer can be treated like a string array, each name string is null-padded
+to a size of KVM_STATS_NAME_LEN;
+This ioclt only needs to be called once on running VMs on the same architecture.
+
+4.133 KVM_STATS_GET_DATA
+-------------------------
+
+:Capability: KVM_CAP_STATS_BINARY_FORM
+:Architectures: all
+:Type: vm ioctl, vcpu ioctl
+:Parameters: struct kvm_stats_data (in/out)
+:Returns: 0 on success, < 0 on error
+
+::
+
+  struct kvm_stats_data {
+	__u32 size;
+	__u64 data[0];
+  };
+
+This ioctl is used to get the aggregated statistics data for VM or vCPU.
+Users must use KVM_STATS_GET_INFO to find the number of statistics.
+They must allocate a buffer of the appropriate size num_stats * sizeof(data[0])
+immediately following struct kvm_stats_data. The size field of kvm_stats_data
+must contain the buffer size as an input.
+The data buffer 1-1 maps to name strings buffer in sequential order.
+This ioctl is usually called periodically to pull statistics data.
+
 5. The kvm_run structure
 ========================
 
@@ -6721,3 +6791,12 @@  vcpu_info is set.
 The KVM_XEN_HVM_CONFIG_RUNSTATE flag indicates that the runstate-related
 features KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR/_CURRENT/_DATA/_ADJUST are
 supported by the KVM_XEN_VCPU_SET_ATTR/KVM_XEN_VCPU_GET_ATTR ioctls.
+
+8.31 KVM_CAP_STATS_BINARY_FORM
+------------------------------
+
+:Architectures: all
+
+This capability indicates that KVM supports retrieving aggregated statistics
+data in binary format with corresponding VM/VCPU ioctl KVM_STATS_GET_INFO,
+KVM_STATS_GET_NAMES and KVM_STATS_GET_DATA.
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 1ea297458306..f2dabf457717 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1164,7 +1164,6 @@  static inline bool kvm_is_error_gpa(struct kvm *kvm, gpa_t gpa)
 
 #define VM_STAT_COUNT		(sizeof(struct kvm_vm_stat)/sizeof(ulong))
 #define VCPU_STAT_COUNT		(sizeof(struct kvm_vcpu_stat)/sizeof(u64))
-#define KVM_STATS_NAME_LEN	32
 
 /* Make sure it is synced with fields in struct kvm_vm_stat. */
 extern const char kvm_vm_stat_strings[][KVM_STATS_NAME_LEN];
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index f6afee209620..ad185d4c5e42 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1078,6 +1078,7 @@  struct kvm_ppc_resize_hpt {
 #define KVM_CAP_DIRTY_LOG_RING 192
 #define KVM_CAP_X86_BUS_LOCK_EXIT 193
 #define KVM_CAP_PPC_DAWR1 194
+#define KVM_CAP_STATS_BINARY_FORM 195
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -1853,4 +1854,63 @@  struct kvm_dirty_gfn {
 #define KVM_BUS_LOCK_DETECTION_OFF             (1 << 0)
 #define KVM_BUS_LOCK_DETECTION_EXIT            (1 << 1)
 
+/* Available with KVM_CAP_STATS_BINARY_FORM */
+
+#define KVM_STATS_NAME_LEN		32
+
+/**
+ * struct kvm_stats_info - statistics information
+ *
+ * Used as parameter for ioctl %KVM_STATS_GET_INFO.
+ *
+ * @num_stats: On return, the number of statistics data of vm or vcpu.
+ *
+ */
+struct kvm_stats_info {
+	__u32 num_stats;
+};
+
+/**
+ * struct kvm_stats_names - string list of statistics names
+ *
+ * Used as parameter for ioctl %KVM_STATS_GET_NAMES.
+ *
+ * @size: Input from user, indicating the size of buffer after the struture.
+ * @names: Buffer of name string list for vm or vcpu. Each string is
+ *	null-padded to a size of %KVM_STATS_NAME_LEN.
+ *
+ * Users must use %KVM_STATS_GET_INFO to find the number of
+ * statistics. They must allocate a buffer of the appropriate
+ * size (>= &struct kvm_stats_info @num_stats * %KVM_STATS_NAME_LEN)
+ * immediately following this struture.
+ */
+struct kvm_stats_names {
+	__u32 size;
+	__u8  names[0];
+};
+
+/**
+ * struct kvm_stats_data - statistics data array
+ *
+ * Used as parameter for ioctl %KVM_STATS_GET_DATA.
+ *
+ * @size: Input from user, indicating the size of buffer after the struture.
+ * @data: Buffer of statistics data for vm or vcpu.
+ *
+ * Users must use %KVM_STATS_GET_INFO to find the number of
+ * statistics. They must allocate a buffer of the appropriate
+ * size (>= &struct kvm_stats_info @num_stats * sizeof(@data[0])
+ * immediately following this structure.
+ * &struct kvm_stats_names @names 1-1 maps to &structkvm_stats_data
+ * @data in sequential order.
+ */
+struct kvm_stats_data {
+	__u32 size;
+	__u64 data[0];
+};
+
+#define KVM_STATS_GET_INFO		_IOR(KVMIO, 0xcc, struct kvm_stats_info)
+#define KVM_STATS_GET_NAMES		_IOR(KVMIO, 0xcd, struct kvm_stats_names)
+#define KVM_STATS_GET_DATA		_IOR(KVMIO, 0xce, struct kvm_stats_data)
+
 #endif /* __LINUX_KVM_H */