Hypervisor information for the virtual server user

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The virtual server user can use the emulated Store Hypervisor Information (STHYI) instruction to retrieve information about the IBM Z® hardware and the LPAR on which the KVM host runs.

The information includes:

The CPU count, by type (CP or IFL)
Limitations for shared CPUs
CEC and LPAR identifiers

KVM guests use the qclib and the GCC inline assembly to run the emulated instruction. For an example, see arch/s390/kvm/sthyi.c in the Linux® source tree.

The emulated STHYI instruction provides information through a response buffer with three data sections:

The header section, at the beginning of the response buffer, which identifies the locations and length of the sections that follow.
The machine section.
The partition section.

Header section

Length	Data Type	Offset (dec)	Name	Contents
1	Bitstring	0	INFHFLG1	Header Flag Byte 1 These flag settings indicate the environment that the instruction was executed in and may influence the value of the validity bits. The validity bits, and not these flags, should be used to determine if a field is valid. 0x80 Global Performance Data unavailable. 0x40 One or more hypervisor levels below this level does not support the STHYI instruction. When this flag is set the value of INFGPDU is not meaningful because the state of the Global Performance Data setting cannot be determined. 0x20 Virtualization stack is incomplete. This bit indicates one of two cases: One or more hypervisor levels does not support the STHYI instruction. For this case, INFSTHYI will also be set. There were more than three levels of guest/hypervisor information to report. 0x10 Execution environment is not within a logical partition.
1	Bitstring	1	INFHFLG2	Header Flag Byte 2 reserved for IBM® use
1	Bitstring	2	INFHVAL1	Header Validity Byte 1 reserved for IBM use
1	Bitstring	3	INFHVAL2	Header Validity Byte 2 reserved for IBM use
3		4		Reserved for future IBM use
1	Unsigned Binary Integer	7	INFHYGCT	Count of Hypervisor and Guest Sections
2	Unsigned Binary Integer	8	INFHTOTL	Total length of response buffer
2	Unsigned Binary Integer	10	INFHDLN	Length of Header Section mapped by INF0HDR
2	Unsigned Binary Integer	12	INFMOFF	Offset to Machine Section mapped by INF0MAC
2	Unsigned Binary Integer	14	INFMLEN	Length of Machine Section
2	Unsigned Binary Integer	16	INFPOFF	Offset to Partition Section mapped by INF0PAR
2	Unsigned Binary Integer	18	INFPLEN	Length of Partition Section
2	Unsigned Binary Integer	20	INFHOFF1	Offset to Hypervisor Section1 mapped by INF0HYP
2	Unsigned Binary Integer	22	INFHLEN1	Length of Hypervisor Section1
2	Unsigned Binary Integer	24	INFGOFF1	Offset to Guest Section1 mapped by INF0GST
2	Unsigned Binary Integer	26	INFGLEN1	Length of Guest Section1
2	Unsigned Binary Integer	28	INFHOFF2	Offset to Hypervisor Section2 mapped by INF0HYP
2	Unsigned Binary Integer	30	INFHLEN2	Length of Hypervisor Section2
2	Unsigned Binary Integer	32	INFGOFF2	Offset to Guest Section2 mapped by INF0GST
2	Unsigned Binary Integer	34	INFGLEN2	Length of Guest Section2
2	Unsigned Binary Integer	36	INFHOFF3	Offset to Hypervisor Section3 mapped by INF0HYP
2	Unsigned Binary Integer	38	INFHLEN3	Length of Hypervisor Section3
2	Unsigned Binary Integer	40	INFGOFF3	Offset to Guest Section3 mapped by INF0GST
2	Unsigned Binary Integer	42	INFGLEN3	Length of Guest Section3
4		44		Reserved for future IBM use

Format machine section

Length	Data Type	Offset (dec)	Name	Contents
1	Bitstring	0	INFMFLG1	Machine Flag Byte 1 reserved for IBM use
1	Bitstring	1	INFMFLG2	Machine Flag Byte 2 reserved for IBM use
1	Bitstring	2	INFMVAL1	Machine Validity Byte 1 0x80 Processor Count Validity. When this bit is on, it indicates that INFMSCPS, INFMDCPS, INFMSIFL, and INFMDIFL contain valid counts. The validity bit may be off when: STHYI support is not available on a lower level hypervisor, or Global Performance Data is not enabled. 0x40 Machine ID Validity. This bit being on indicates that a SYSIB 1.1.1 was obtained from STSI and information reported in the following fields is valid: INFMTYPE, INFMMANU, INFMSEQ, and INFMPMAN. 0x20 Machine Name Validity. This bit being on indicates that the INFMNAME field is valid.
1	Bitstring	3	INFMVAL2	Machine Validity Byte 2 reserved for IBM use
2	Unsigned Binary Integer	4	INFMSCPS	Number of shared CPs configured in the machine or in the physical partition if the system is physically partitioned
2	Unsigned Binary Integer	6	INFMDCPS	Number of dedicated CPs configured in this machine or in the physical partition if the system is physically partitioned
2	Unsigned Binary Integer	8	INFMSIFL	Number of shared IFLs configured in this machine or in the physical partition if the system is physically partitioned.
2	Unsigned Binary Integer	10	INFMDIFL	Number of dedicated IFLs configured in this machine or in the physical partition if the system is physically partitioned.
8	EBCDIC	12	INFMNAME	Machine Name
4	EBCDIC	20	INFMTYPE	Type
16	EBCDIC	24	INFMMANU	Manufacturer
16	EBCDIC	40	INFMSEQ	Sequence Code
4	EBCDIC	56	INFMPMAN	Plant of Manufacture
4		60		Reserved for future IBM use

Format partition section

Length	Data Type	Offset (dec)	Name	Contents
1	Bitstring	0	INFPFLG1	Partition Flag Byte 1 0x80 Multithreading (MT) is enabled.
1	Bitstring	1	INFPFLG2	Partition Flag Byte 2 reserved for IBM use
1	Bitstring	2	INFPVAL1	Partition Validity Byte 1 0x80 This bit being on indicates that INFPSCPS, INFPDCPS, INFPSIFL, and INFPDIFL contain valid counts. 0x40 This bit being on indicates that INFPWBCP and INFPWBIF are valid 0x20 This bit being on indicates that INFPABCP and INFPABIF are valid. 0x10 This bit being on indicates that a SYSIB 2.2.2 was obtained from STSI and information reported in the following fields is valid: INFPPNUM and INFPPNAM. 0x08 This bit being on indicates that INFPLGNM, INFPLGCP, and INFPLGIF are valid.
1	Bitstring	3	INFPVAL2	Partition Validity Byte 2 reserved for IBM use
2	Unsigned Binary Integer	4	INFPPNUM	Logical partition number
2	Unsigned Binary Integer	6	INFPSCPS	Number of shared logical CPs configured for this partition. Count of cores when MT is enabled.
2	Unsigned Binary Integer	8	INFPDCPS	Number of dedicated logical CPs configured for this partition. Count of cores when MT is enabled.
2	Unsigned Binary Integer	10	INFPSIFL	Number of shared logical IFLs configured for this partition. Count of cores when MT is enabled.
2	Unsigned Binary Integer	12	INFPDIFL	Number of dedicated logical IFLs configured for this partition. Count of cores when MT is enabled.
2		14		Reserved for future IBM use
8	EBCIDIC	16	INFPPNAM	Logical partition name
4	Unsigned Binary Integer	24	INFPWBCP	Partition weight-based capped capacity for CPs, a scaled number where X'00010000' represents one core. Zero if not capped.
4	Unsigned Binary Integer	28	INFPABCP	Partition absolute capped capacity for CPs, a scaled number where X'00010000' represents one core. Zero if not capped.
4	Unsigned Binary Integer	32	INFPWBIF	Partition weight-based capped capacity for IFLs, a scaled number where X'00010000' represents one core. Zero if not capped.
4	Unsigned Binary Integer	36	INFPABIF	Partition absolute capped capacity for IFLs, a scaled number where X'00010000' represents one core. Zero if not capped.
8	EBCIDIC	40	INFPLGNM	LPAR group name. Binary zeros when the partition is not in an LPAR group. EBCDIC and padded with blanks on the right when in a group. The group name is reported only when there is a group cap on CP or IFL CPU types and the partition has the capped CPU type.
4	Unsigned Binary Integer	48	INFPLGCP	LPAR group absolute capacity value for CP CPU type when nonzero. This field will be nonzero only when INFPLGNM is nonzero and a cap is defined for the LPAR group for the CP CPU type. When nonzero, contains a scaled number where X'00010000' represents one core.
4	Unsigned Binary Integer	52	INFPLGIF	LPAR group absolute capacity value for IFL CPU type when nonzero. This field will be nonzero only when INFPLGNM is nonzero and a cap is defined for the LPAR group for the IFL CPU type. When nonzero, contains a scaled number where X'00010000' represents one core.