Demand in China has begun surging for a business that, in theory, shouldn't exist: the repair of advanced Nvidia artificial intelligence chipsets that the U.S. has banned the export of to its trade and tech rival.

As the top chip company, Nvidia's chips are in high demand from the largest companies, like Amazon and Microsoft, that are building out huge AI businesses. They themselves are serving other giants with AI tools and services in partnership with Nvidia, offering access to the chipmaker's powerful technology.

Nvidia Corp. and Advanced Micro Devices Inc. plan to resume sales of some AI chips in China after securing Washington’s assurances that such shipments would get approved, a dramatic reversal from the Trump administration’s earlier stance on measures designed to limit Beijing’s AI ambitions.