The effect on Intel is far more severe than on other architectures. There were three vulnerabilities, two grouped together as "spectre" and one called "meltdown." Intel products are uniquely vulnerable to the meltdown attack, while many CPUs are vulnerable to spectre. The summary AFAIUI is that for most CPUs you can attack userspace processes with these techniques (think Javascript running in a browser), while for Intel CPUs you can also attack the kernel. Intel CPUs also seem to be somewhat easier to attack than others because of a higher-bandwidth side channel.
> Intel products are uniquely vulnerable to the meltdown attack
More precisely, there is only a PoC for Intel at this time. AMD processors are believed to not be vulnerable. Some ARM processors _are_ believed to be vulnerable.
> for most CPUs you can attack userspace processes with these techniques
I think that's almost but not quite exactly right.
Spectre variant 2 attacks vulnerable indirect jump code patterns that exist in the kernel (or some other process), but doesn't require running the attacker's code.
Spectre variant 1 allows you to infer the contents of memory in the same address space, so that's the one where you'd use eBPF to attack the kernel.
Meltdown (variant 3) if I understand correctly can infer memory contents of other address spaces without relying on any assumptions about the code running in the other address space.
I'm curious about AMD not being vulnerable, mostly because this page: https://www.kb.cert.org/vuls/id/584653 makes me think that AMD has admitted to being vulnerable.
That page talks about both Meltdown and Spectre, as far as I can tell. AMD is vulnerable to Spectre; everyone agrees on that. According to https://www.amd.com/en/corporate/speculative-execution AMD claims it's not vulnerable to Meltdown (aka "Variant Three").
A minor correction, ARM's upcoming A75 core looks like it will be vulnerable to Meltdown too. But since it isn't intended for use on server workloads the performance impact of the fix shouldn't be very significant.
