KVM: s390: vsie: fix virtual/physical address in unpin_scb()

In commit 77b5334 ("KVM: s390: VSIE: sort out virtual/physical
address in pin_guest_page"), only pin_scb() has been updated. This
means that in unpin_scb() a virtual address was still used directly as
physical address without conversion. The resulting physical address is
obviously wrong and most of the time also invalid.

Since commit d0ef8d9 ("KVM: s390: Use kvm_release_page_dirty() to
unpin "struct page" memory"), unpin_guest_page() will directly use
kvm_release_page_dirty(), instead of kvm_release_pfn_dirty(), which has
since been removed.

One of the checks that were performed by kvm_release_pfn_dirty() was to
verify whether the page was valid at all, and silently return
successfully without doing anything if the page was invalid.

When kvm_release_pfn_dirty() was still used, the invalid page was thus
silently ignored. Now the check is gone and the result is an Oops.
This also means that when running with a V!=R kernel, the page was not
released, causing a leak.

The solution is simply to add the missing virt_to_phys().

Fixes: 77b5334 ("KVM: s390: VSIE: sort out virtual/physical address in pin_guest_page")
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
Link: https://lore.kernel.org/r/20241210083948.23963-1-imbrenda@linux.ibm.com
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20241210083948.23963-1-imbrenda@linux.ibm.com>

Author: Claudio Imbrenda

arch/s390/kvm/vsie.c

@@ -854,7 +854,7 @@ static int pin_blocks(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 static void unpin_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page,
 		      gpa_t gpa)
 {
-	hpa_t hpa = (hpa_t) vsie_page->scb_o;
+	hpa_t hpa = virt_to_phys(vsie_page->scb_o);
 
 	if (hpa)
 		unpin_guest_page(vcpu->kvm, gpa, hpa);