From f7a960affc6e5a33e8c7fcef065affc4f0461041 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Wed, 3 Sep 2014 21:23:13 +0200 Subject: [PATCH] KVM: s390/cmm: Fix prefix handling for diag 10 balloon 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 Reviewed-by: Thomas Huth --- 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 b374b6cb7785..9254afff250c 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; } -- 2.20.1