[PATCH 6.18.y 1/2] KVM: arm64: Ensure level is always initialized when relaxing perms

[Marc Zyngier <maz@kernel.org>]

From: Oliver Upton <oupton@kernel.org>

stage2_update_leaf_attrs() returns early before writing to @level if the
table walker returned an error. At the same time,
kvm_pgtable_stage2_relax_perms() uses the level as a TLBI TTL hint when the
error was EAGAIN, indicating the vCPU raced with a table update and the TLB
entry it hit is now stale.

Fall back to an unknown TTL if none was provided by the walk.

Cc: stable@vger.kernel.org
Fixes: be097997a273 ("KVM: arm64: Always invalidate TLB for stage-2 permission faults")
Signed-off-by: Oliver Upton <oupton@kernel.org>
Reviewed-by: Wei-Lin Chang <weilin.chang@arm.com>
Link: https://patch.msgid.link/20260701231620.3300204-2-oupton@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
(cherry picked from commit 100baf0184896f859290a684f864b8200d8ac872)
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/hyp/pgtable.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index cbf8cd2e16735..3e056afea0722 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1291,7 +1291,7 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr,
 				   enum kvm_pgtable_prot prot, enum kvm_pgtable_walk_flags flags)
 {
 	int ret;
-	s8 level;
+	s8 level = TLBI_TTL_UNKNOWN;
 	kvm_pte_t set = 0, clr = 0;
 
 	if (prot & KVM_PTE_LEAF_ATTR_HI_SW)
-- 
2.47.3