I think transparent memory encryption effectively defeats RowHammer attacks.
The CPU has a key it uses to decrypt memory on access - and that key is never known by the operating system or any software running within it. If you use RowHammer to access the "wrong" memory location, the decrypted values would be random garbage.
Pure hardware protection, no changes to memory chips, almost no runtime performance cost, effective security.
AFAIK RowHammer is already a non issue on the latest hardware since the module will speculatively refresh rows that may be vulnerable. ie: If a ton of writes happen to row B then rows A and C will have a refresh triggered too.
The CPU has a key it uses to decrypt memory on access - and that key is never known by the operating system or any software running within it. If you use RowHammer to access the "wrong" memory location, the decrypted values would be random garbage.
Pure hardware protection, no changes to memory chips, almost no runtime performance cost, effective security.