KVM: arm/arm64: Release kvm->mmu_lock in loop to prevent starvation

Do cond_resched_lock() in stage2_flush_memslot() like what is done in
unmap_stage2_range() and other places holding mmu_lock while processing
a possibly large range of memory.

Signed-off-by: Jiang Yi <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Reviewed-by: Suzuki K Poulose <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Jiang Yi

arch/arm64/kvm/mmu.c

@@ -422,6 +422,9 @@ static void stage2_flush_memslot(struct kvm *kvm,
 		next = stage2_pgd_addr_end(kvm, addr, end);
 		if (!stage2_pgd_none(kvm, *pgd))
 			stage2_flush_puds(kvm, pgd, addr, next);
+
+		if (next != end)
+			cond_resched_lock(&kvm->mmu_lock);
 	} while (pgd++, addr = next, addr != end);
 }