Revert "KVM: arm64: Reschedule as needed when destroying the stage-2 page-tables"

This reverts commit e9abe311f35631a999fe38c86f26f0e48ffe46d5.

syzkaller has managed to tease out multiple bugs in this change and
fixing-forward didn't remedy the situation. Considering newly-introduced
memory safety issues the potential for scheduler stalls don't seem that
bad in comparison

Link: https://lore.kernel.org/kvmarm/68c09802.050a0220.3c6139.000d.GAE@google.com/
Message-ID: <20250910180930.3679473-2-oliver.upton@linux.dev>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index e78ffcb4bfe900774364e42a9214db2ea7b07b88..862bfa272f0a97d3801be94c4d748bb61ce3b177 100644 (file)
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -904,35 +904,11 @@ static int kvm_init_ipa_range(struct kvm_s2_mmu *mmu, unsigned long type)
        return 0;
 }
 
-/*
- * Assume that @pgt is valid and unlinked from the KVM MMU to free the
- * page-table without taking the kvm_mmu_lock and without performing any
- * TLB invalidations.
- *
- * Also, the range of addresses can be large enough to cause need_resched
- * warnings, for instance on CONFIG_PREEMPT_NONE kernels. Hence, invoke
- * cond_resched() periodically to prevent hogging the CPU for a long time
- * and schedule something else, if required.
- */
-static void stage2_destroy_range(struct kvm_pgtable *pgt, phys_addr_t addr,
-                                  phys_addr_t end)
-{
-       u64 next;
-
-       do {
-               next = stage2_range_addr_end(addr, end);
-               KVM_PGT_FN(kvm_pgtable_stage2_destroy_range)(pgt, addr,
-                                                               next - addr);
-               if (next != end)
-                       cond_resched();
-       } while (addr = next, addr != end);
-}
-
 static void kvm_stage2_destroy(struct kvm_pgtable *pgt)
 {
        unsigned int ia_bits = VTCR_EL2_IPA(pgt->mmu->vtcr);
 
-       stage2_destroy_range(pgt, 0, BIT(ia_bits));
+       KVM_PGT_FN(kvm_pgtable_stage2_destroy_range)(pgt, 0, BIT(ia_bits));
        KVM_PGT_FN(kvm_pgtable_stage2_destroy_pgd)(pgt);
 }