There's three vulnerabilities, variant 3 is being called Meltdown and variant 1 and 2 are being called Spectre (or Spectre 1 and Spectre 2).
Meltdown (which looks to only affect Intel CPUs - nearly all of them since 1995!) patches are being pushed out to Windows, macOS High Sierra (it's been fixed since 10.13.2, released nearly a month ago) and the Linux kernel. There's going to be a performance hit for Intel CPUs because of Kernel Page Table Isolation (KPTI), depending how old the CPU is and whether or not the CPU has Process-Context Identifiers (CPID) or not. Also the performance hit will depend on the workload(s).
Spectre on the other hand looks to affect Intel with both variant 1 and 2 whereas AMD and ARM CPUs are affected by variant 1 (AMD on Linux only? Some confusion there). Unlike Meltdown, Spectre is way harder to fix. Looks like applications will have to patch this one, in addition to stuff being added to OSes to help mitigate it. AMD has said they can fix Spectre 1 through software (again, Linux only?), after they do they won't be vulnerable to Spectre 1 anymore. Man, I wish I bought some AMD stock a few days ago!
Both Meltdown and Spectre are going to be a nightmare for cloud, enterprise and the IT industry in general.
https://meltdownattack.com/