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s390x/cpumodel: we are always in zarchitecture mode

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In QEMU, a guest VCPU always started in and never was able to leave
z/Architecture mode. Now we have an architected way of showing this
condition.

The SIGP SET ARCHITECTURE instruction is simply rejected. Linux as guest
seems to not care about the return value, which is a good thing
The new handling is just like already being in z/Architecture mode.

We'll not try to fake absence of this facility, but still not indicate
the facility in case some strange CPU model turned z/Architecture off
completely (which doesn't work either way but let's us see how a
guest would react on a lack of this facility).

Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Jason J. Herne 2016-09-01 10:56:49 +02:00 • committed by Christian Borntraeger
parent 6da5c593bb
commit 075e52b816
2 changed files with 14 additions and 29 deletions
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5
target/s390x/cpu_features.c
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@ -337,8 +337,9 @@ void s390_fill_feat_block(const S390FeatBitmap features, S390FeatType type,
int bit_nr;
if (type == S390_FEAT_TYPE_STFL && test_bit(S390_FEAT_ZARCH, features)) {
/* z/Architecture is always active if around */
data[0] |= 0x20;
/* Features that are always active */
data[0] |= 0x20; /* z/Architecture */
data[17] |= 0x20; /* Configuration-z-architectural-mode */
}
feat = find_first_bit(features, S390_FEAT_MAX);