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Commit 2cef4deb authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Gleb Natapov
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KVM: s390: Dont do a gmap update on minor memslot changes 



Some memslot updates dont affect the gmap implementation,
e.g. setting/unsetting dirty tracking. Since a gmap update
will cause tlb flushes and segment table invalidations we
want to avoid that.

Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
parent 9a6d77d5

arch/s390/kvm/kvm-s390.c

+10 −0
Original line number Diff line number Diff line
@@ -1007,6 +1007,16 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, 
{

	int rc;



	/* If the basics of the memslot do not change, we do not want

	 * to update the gmap. Every update causes several unnecessary

	 * segment translation exceptions. This is usually handled just

	 * fine by the normal fault handler + gmap, but it will also

	 * cause faults on the prefix page of running guest CPUs.

	 */

	if (old->userspace_addr == mem->userspace_addr &&

	    old->base_gfn * PAGE_SIZE == mem->guest_phys_addr &&

	    old->npages * PAGE_SIZE == mem->memory_size)

		return;



	rc = gmap_map_segment(kvm->arch.gmap, mem->userspace_addr,

		mem->guest_phys_addr, mem->memory_size);