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@xxxxxxxxxx>
Reviewed-by: Thomas Huth <thuth@xxxxxxxxxxxxxxxxxx>
---
arch/s390/kvm/diag.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)
diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
index b374b6c..9254aff 100644
--- a/arch/s390/kvm/diag.c
+++ b/arch/s390/kvm/diag.c
@@ -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;
}
--
1.8.4.2
--
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