KVM: arm64: Fix initialisation order in __pkvm_init_finalise()

commit 5bb0aed57ba944f8c201e4e82ec066e0187e0f85 upstream.

fix_host_ownership() walks the hypervisor's stage-1 page-table to
adjust the host's stage-2 accordingly. Any such adjustment that
requires cache maintenance operations depends on the per-CPU hyp
fixmap being present. However, fix_host_ownership() is currently
called before fix_hyp_pgtable_refcnt() and hyp_create_fixmap(), so
the fixmap does not yet exist when it runs.

This is benign today because the host stage-2 starts empty and no
CMOs are needed, but it becomes a latent crash as soon as
fix_host_ownership() is extended to operate on a non-empty
page-table.

Reorder the calls so that fix_hyp_pgtable_refcnt() and
hyp_create_fixmap() complete before fix_host_ownership() is invoked.

Fixes: 0d16d12eb26e ("KVM: arm64: Fix-up hyp stage-1 refcounts for all pages mapped at EL2")
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260424084908.370776-7-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index 90bd014e952fbc57a104444800cf78afe4400683..97643fc02d9257081132296b3c172703b10d39ce 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -312,15 +312,15 @@ void __noreturn __pkvm_init_finalise(void)
        };
        pkvm_pgtable.mm_ops = &pkvm_pgtable_mm_ops;
 
-       ret = fix_host_ownership();
+       ret = fix_hyp_pgtable_refcnt();
        if (ret)
                goto out;
 
-       ret = fix_hyp_pgtable_refcnt();
+       ret = hyp_create_fixmap();
        if (ret)
                goto out;
 
-       ret = hyp_create_fixmap();
+       ret = fix_host_ownership();
        if (ret)
                goto out;