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

In commit 77b533411595 ("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 d0ef8d9fbebe ("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: 77b533411595 ("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>

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 150b9387860ad2e511a5e8b4a0e9c73b8a12ddbb..a687695d8f68e740299b79a5f9a30e75013486a2 100644 (file)
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -854,7 +854,7 @@ unpin:
 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);