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KVM: s390/cmm: Fix prefix handling for diag 10 balloon

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The old handling of prefix pages was broken in the diag10 ballooner.
We now rely on gmap_discard to check for start > end and do a
slow path if the prefix swap pages are affected:
1. discard the pages from start to prefix
2. discard the absolute 0 pages
3. discard the pages after prefix swap to end

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
This commit is contained in:
Christian Borntraeger 2014-09-03 21:23:13 +02:00
parent 6b331952f1
commit f7a960affc
1 changed files with 18 additions and 8 deletions
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26
arch/s390/kvm/diag.c
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@ -28,22 +28,32 @@ static int diag_release_pages(struct kvm_vcpu *vcpu)
start = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
end = vcpu->run->s.regs.gprs[vcpu->arch.sie_block->ipa & 0xf] + 4096;
if (start & ~PAGE_MASK || end & ~PAGE_MASK || start > end
if (start & ~PAGE_MASK || end & ~PAGE_MASK || start >= end
|| start < 2 * PAGE_SIZE)
return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
VCPU_EVENT(vcpu, 5, "diag release pages %lX %lX", start, end);
vcpu->stat.diagnose_10++;
/* we checked for start > end above */
if (end < prefix || start >= prefix + 2 * PAGE_SIZE) {
/*
* We checked for start >= end above, so lets check for the
* fast path (no prefix swap page involved)
*/
if (end <= prefix || start >= prefix + 2 * PAGE_SIZE) {
gmap_discard(vcpu->arch.gmap, start, end);
} else {
if (start < prefix)
gmap_discard(vcpu->arch.gmap, start, prefix);
if (end >= prefix)
gmap_discard(vcpu->arch.gmap,
prefix + 2 * PAGE_SIZE, end);
/*
* This is slow path. gmap_discard will check for start
* so lets split this into before prefix, prefix, after
* prefix and let gmap_discard make some of these calls
* NOPs.
*/
gmap_discard(vcpu->arch.gmap, start, prefix);
if (start <= prefix)
gmap_discard(vcpu->arch.gmap, 0, 4096);
if (end > prefix + 4096)
gmap_discard(vcpu->arch.gmap, 4096, 8192);
gmap_discard(vcpu->arch.gmap, prefix + 2 * PAGE_SIZE, end);
}
return 0;
}