page-table address is less than 4096. On some
models, this interruption also takes place when
the page-table origin is less than4096 (2).
9. This function invalidates a page-table entry just
-asufliel1\tVJtt;m-A.-'fE--¥AGE--'fABE-E----- ENTRY instruction were executed with the
problem-state bit set to zero. In particular,
certain entries in the translation-Iookaside
buffer of all configuredCPUs must be purged.
If a protection or addressing exception is
encountered, a program interruption for
protection or addressing takes place in the
normal manner (3).
Figure 23 summarizes the fields used.
Programming Notes
1. IPTE is not assisted if the page-table entry is in
the first 4K bytes of real storage because
VM/3 70 does not map that storage as virtual
equals real.
2. A translation-specification exception for a
format error in bits 8-12 of real control register
o cannot arise in executing IPTE underVM/370 because VM/370 always executes
virtual-machine instructions with real DAT on,
and a format error would prevent the fetching
of any virtual-machine instruction.LOAD CONTROL The LOAD CONTROL instruction is executed for
a virtual machine if the corresponding function of
the shadow-table-bypass assist is activated; the
instruction loads virtual control register 1 only
when the virtual machine is in the EC mode with
DAT on.
The load-control function of the shadow-table
bypass assist is invoked each time aCPU attempts
to execute aLOAD CONTROL instruction when
the problem-state bit of the real PSW is one. The
execution of this function consists in performing
the following steps:
1. If bits0-3 of control register 6 are not 10XO binary, a program interruption takes place for a
privileged-operation exception, and execution
FieldControl Address Offset No. of
Name Block Type (Hex) BytesContents of the LOAD CONTROL instruction is
suppressed(I.A.l)". 2. The assist control word, MICACF, is fetched
with a key of zero. Execution ends if an (l.A.2.A.I).
3. Execution ends with a program interruption for
a privileged-operation exception if bits 8 and
15 of the assist control word are not both ones
( l.A.2.A.2).
4. MICVPSW, which contains the address of the
virtualPSW, is fetched with a key of zero.
Execution ends if an addressing condition is
encountered (l.A.2.A.3).
S.VMPSW, the virtual PSW, is fetched with a key
of zero. Execution ends if an addressing
condition is encountered (l.A.2.A.4).
6. Execution ends with a program interruption for
a privileged-operation exception if bits 5 and
12 of the virtualPSW are not both ones (that is, if the virtual machine is not in the BC mode
with DAT on) (l.A.2.A.S).
7. Execution ends with a program interruption for
a privileged-operation exception if the R
J
and
R3 fields of theLOAD CONTROL instruction
are not both one (hex) (1.A.2.B).
8 .. If an access condition is encountered in
fetching the second halfword of theLOAD CONTROL instruction, execution of this
function ends, and a program interruptiontakes place with that access exception indicated
(l.B).
9. TheLOAD CONTROL instruction is executed
just as if the real problem-state bit were If an exception is recognized, execution o£ this function ends, and a program interruption takes place indicating that exception (2). 10. If the value in real control register 1 was .not changed, execution of the LOAD CONTROL instruction is complete (3).
11. MICCREG, the word containingthe address of
theECBLOK control block,is fetched with .a key of zero. Execution of the LOAD CONTROL instruction is terminated, and a IMICVPSW MICBLOK Real I 8 I 4 Address of VMPSW IAssist contral word I 'Virtual PSW bits 0-lS
t /MICACF VMPSW Operand 2 lMICBLoKIReal VMBLOK Real
Real
14
o
4
2
2 Page-table entry
Figure 23. Fields Used in INVALIDATEPAGE TABLE ENTRY
Shadow-Table-Bypass Assist 33
models, this interruption also takes place when
the page-table origin is less than
9. This function invalidates a page-table entry just
-as
problem-state bit set to zero. In particular,
certain entries in the translation-Iookaside
buffer of all configured
If a protection or addressing exception is
encountered, a program interruption for
protection or addressing takes place in the
normal manner (3).
Figure 23 summarizes the fields used.
Programming Notes
1. IPTE is not assisted if the page-table entry is in
the first 4K bytes of real storage because
VM/3 7
equals real.
2. A translation-specification exception for a
format error in bits 8-12 of real control register
o cannot arise in executing IPTE under
virtual-machine instructions with real DAT on,
and a format error would prevent the fetching
of any virtual-machine instruction.
a virtual machine if the corresponding function of
the shadow-table-bypass assist is activated; the
instruction loads virtual control register 1 only
when the virtual machine is in the EC mode with
DAT on.
The load-control function of the shadow-table
bypass assist is invoked each time a
to execute a
the problem-state bit of the real PSW is one. The
execution of this function consists in performing
the following steps:
1. If bits
privileged-operation exception, and execution
Field
Name Block Type (Hex) Bytes
suppressed
with a key of zero. Execution ends if an
3. Execution ends with a program interruption for
a privileged-operation exception if bits 8 and
15 of the assist control word are not both ones
( l.A.2.A.2).
4. MICVPSW, which contains the address of the
virtual
Execution ends if an addressing condition is
encountered (l.A.2.A.3).
S.
of zero. Execution ends if an addressing
condition is encountered (l.A.2.A.4).
6. Execution ends with a program interruption for
a privileged-operation exception if bits 5 and
12 of the virtual
with DAT on) (l.A.2.A.S).
7. Execution ends with a program interruption for
a privileged-operation exception if the R
J
and
R3 fields of the
are not both one (hex) (1.A.2.B).
8 .. If an access condition is encountered in
fetching the second halfword of the
function ends, and a program interruption
(l.B).
9. The
just as if the real problem-state bit were
11. MICCREG, the word containing
the
t
Real
14
o
4
2
2 Page-table entry
Figure 23. Fields Used in INVALIDATE
Shadow-Table-Bypass Assist 33