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The threads look exactly like real processors to the kernel. The only difference as far as the kernel is concerned is that they share the L1 cache.
by bonzini 8y ago
The threads look exactly like real processors to the kernel. The only difference as far as the kernel is concerned is that they share the L1 cache.
- dnautics 8y agoExactly. So you can have insecure boundary between threads because they share L1 cache. Is my understanding of how meltdown works incorrect?
- bonzini 8y agoYou're thinking of Spectre. Meltdown doesn't need to share cache, a thread can just read kernel mappings into its own L1. Kernel mappings typically include the whole physical memory (on 64-bit machines where virtual address space is huge).