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I have a somewhat naive question. Since this and many similar recent issues are associated with SMT (Spectre, Meltdown), and the concern is about malicious code
by greggyb 8y ago
I have a somewhat naive question. Since this and many similar recent issues are associated with SMT (Spectre, Meltdown), and the concern is about malicious code being run on the same core.
Can IaaS vendors simply restrict VMs to always use whole cores. If you want 3 cores in your VM, you get
1. Core0 Main thread
2. Core0 Hyper thread
3. Core1 Main thread
Core1 Hyper thread is un-allocated
And then we don't have two actors on one core? Or just only offer 2-core VMs.
- wmf 8y agoIt looks like EC2 is already doing this. I don't think they ever shared cores except for t1 and t2.
- wrs 8y ago“Google Compute Engine employs host isolation features which ensure that an individual core is never concurrently shared between distinct virtual machines.” (https://cloud.google.com/blog/products/gcp/protecting-against-the-new-l1tf-speculative-vulnerabilities/ https://cloud.google.com/blog/products/gcp/protecting-agains...)
- johncslack 8y agoYep, that's an important part of the approach used in Azure and Hyper-V. Full details: https://blogs.technet.microsoft.com/virtualization/2018/08/14/hyper-v-hyperclear https://blogs.technet.microsoft.com/virtualization/2018/08/1... Disclosure: Microsoft, Hyper-V team