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authorMichael Mueller2020-02-27 10:10:31 +0100
committerChristian Borntraeger2020-02-27 19:47:13 +0100
commitcc674ef252f4750bdcea1560ff491081bb960954 (patch)
tree8f1735b69f2dd1b8fbd4d535ca5b00b50db8a309 /arch/s390/boot/Makefile
parent04ed89dc4aeba57ab99df16edbd9d06e43d0a2c4 (diff)
KVM: s390: introduce module parameter kvm.use_gisa
The boolean module parameter "kvm.use_gisa" controls if newly created guests will use the GISA facility if provided by the host system. The default is yes. # cat /sys/module/kvm/parameters/use_gisa Y The parameter can be changed on the fly. # echo N > /sys/module/kvm/parameters/use_gisa Already running guests are not affected by this change. The kvm s390 debug feature shows if a guest is running with GISA. # grep gisa /sys/kernel/debug/s390dbf/kvm-$pid/sprintf 00 01582725059:843303 3 - 08 00000000e119bc01 gisa 0x00000000c9ac2642 initialized 00 01582725059:903840 3 - 11 000000004391ee22 00[0000000000000000-0000000000000000]: AIV gisa format-1 enabled for cpu 000 ... 00 01582725059:916847 3 - 08 0000000094fff572 gisa 0x00000000c9ac2642 cleared In general, that value should not be changed as the GISA facility enhances interruption delivery performance. A reason to switch the GISA facility off might be a performance comparison run or debugging. Signed-off-by: Michael Mueller <mimu@linux.ibm.com> Link: https://lore.kernel.org/r/20200227091031.102993-1-mimu@linux.ibm.com Reviewed-by: Cornelia Huck <cohuck@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
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