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Commit f7a960af authored by Christian Borntraeger's avatar Christian Borntraeger
Browse files

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: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: default avatarThomas Huth <thuth@linux.vnet.ibm.com>
parent 6b331952

arch/s390/kvm/diag.c

+18 −8
Original line number Diff line number Diff line
@@ -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)

		/*

		 * 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 (end >= prefix)

			gmap_discard(vcpu->arch.gmap,

				     prefix + 2 * PAGE_SIZE, end);

		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;

}