How do you protect against someone controlling the hypervisor? Read the paper. But the high level is to encrypt memory using keys that cannot leave the processor and are only available to a specific VM ASID (Address Space Identifier), assisted by a secure firmware similar to the Secure Enclave. Attestation uses an on-chip certificate signed by an AMD master key during fabrication.
There were some discussions on this on the linux-kernel mailing list [2]. As I understand it, the current generation of SEV is still somewhat leaky, but there's no fundamental reason why those leaks cannot be closed.
[1] http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2013/... [2] http://www.mail-archive.com/linux-doc@vger.kernel.org/msg025...
With this, the party in control of the system is also in control of that, so every time a new vulnerability is found they can exploit it before patching it to retroactively get access to your data. Or never patch it at all and use the vulnerability itself to forge attestations that the vulnerability is patched.
Depending on how determined you imagine your bad actor host, you can probably never get around things like "zero day is discovered, host disconnects guest from internet preventing you from patching zero day, exploits guest".
Or are you talking about vulnerabilities in SEV itself?
Here's one application for the red team: AV-resistant malware, rootkits and next generation APTs
Homomorphic encryption would allow for "true security" where the party doing the computation doesn't ever have the encryption keys necessary to see what data they're operating on. This is something more akin to a TPM. The key that can read all of the data is in the possession of the party doing the computation, but it's stored in the CPU and the CPU will not give that key to anyone. Theoretically the key could be read off of the CPU but in practice this would require either a flaw, sidechannel, or a lot of time with an electron microscope.
For practical purposes, I believe that all implementations of secure cloud computing are going to be like this where the key is just secured physically. It's possible with homomorphic encryption to have someone securely do computations on data that they can't see all in software, but I just don't see any major breakthroughs happening that would make this fast enough to be practical.
> Attestation uses an on-chip certificate signed by an AMD master key during fabrication.
This is absolutely fantastic for security in the cloud, but it is important to note that this will not protect against nation state level actors.
Rest assured that the USG will obtain the AMD master signing key with or without AMD's permission. Other nation states may do likewise. The rest will have to wait for a leak, and if that key is leaked this feature will become almost nonexistent.
Even a less that perfect protection from the hyper-visor may still have some value.
I'd be more worried about the performance overhead, personally - I can't imagine using this if the impact is significant, and it seems like it almost has to be.
However, they seem to have a strong technical pipeline and they have historically punched above their weight-class. Does it look like they are going to make it?
Just like Intel had the P4 hole that it had to drag its way out of, so now AMD has had Bulldozer. Notice how Intel has been quite conservative with each individual tick/tock, trying to keep their pipeline full. Doing crazy changes risks causing a pipeline stall which could last years. Each new architecture is risky, and AMD screwed up with Bulldozer. From early signs it looks like Zen is a winner, hopefully AMD can stick with it for a while.
Mankind Divided's recommended specs are FX-8350 or i7 3770. The price difference between the two in their heyday was $100 in AMD's favor.
It took about the same amount of time for Intel to release the Core and Core 2 architectures after realising they had made a huge mistake with the Pentium 4.
I've heard some people theorising that Intel might have worked their current architecture into a corner and they might have problems innovating out of it. I guess we will see when information about Zen's performance shows up.
Edit: As the day goes on it seems like they're trading back over $7, so obviously the market disagrees with me :) They were trading around $10 before losing profitability, and in the $20-$40 range during their mid-2000s heyday, so maybe the market is expecting performance closer to that. I think that is optimistic still, but again who knows.
Obliquely, also remember that while Nvidia is winning on the "pure" GPU front with the awesome 1080 etc, the major problem for Nvidia is that its tech needs a host processor, and its ARM attempts are going nowhere (Nintendo NX notwithstanding). AMD does not face this problem. It's becoming clearer that pure-parallel is not always optimal. Hybrid GPU/CPU architectures have a lot of upside as we are seeing with the Xeon Phi use cases, which smackdown on Nvidia bigtime as soon as you mix even the slightest bit of dependency in your algorithms.
I am very bullish on AMD. I believe its stock has double potential, because the price is so catastrophically pessimistic already. And without even talking market valuations, I think we have had enough of monopoly-style price gouging on Xeon and Tesla.
Whatever is happening in the company now is what you will be seeing in 2021 or 2023. Whether they will make it depends on how well the managing team handles that long lead time - for their leaders to give the engineers and product people as much time as possible to keep the company alive until each product comes into being.
No their not, there Q2 financials had them in black.
Probably, but I still think they would do far better with an owner like Qualcomm (granted Qualcomm would still have enough money in the bank to actually do something interesting with AMD after the acquisition).
I guess a big benefit of the separate caches is that if only half cores are in use, you can power half of it down, saving power and TDP.
It also has a bandwidth problem. If 64 threads are vying for access, you either build it with few access ports and it gets choked, or you build it with many access ports which is costly in area, power, & speed.
Two separate peer caches automatically have twice the bandwidth of one similar double-size cache, for the price of NUMA & cache coherency challenges.
There is no one right answer here. Bandwidth is far more important and coherency much easier in a small L1; as you go down the hierarchy, bandwidth needs shrink and coherency is more expensive.
The architecture itself sounds pretty much like what everyone was expecting, a traditional fat and wide core. Their power management and foundry process will probably make the difference as to whether final performance is impressive or not, may also be the cause of the delay.
Anyway, the first benchmark is promising, and I hope Zen can also keep up with Broadwell performance in other benchmarks/workloads, as well as in power efficency.
It's a good mix between high-level and highly-detailed.
It does have a brief introduction on some of the basic execution fundamentals but then it jumps right in, so you will probably need some external introduction if you are not generally familiar with the topic.
1. https://www.amazon.com/Computer-Architecture-Fifth-Quantitat...
2. https://www.amazon.com/Inside-Machine-Introduction-Microproc...
Albeit, slightly older and very technical.
Charles Petzold's "Code: The Hidden Language of Computer Hardware and Software" is also well regarded, but is aimed more at non-technical people.
If it haves it, I would avoid it like a pest, and get an FX-8370 or 8350 to replace my now aging FX-4100. The last thing that I like to have on my computer is a hidden uncontrollable CPU doing things that could affect to my privacy.
If you can tolerate using a different CPU architecture, Raptor Engineering's Talos Secure Workstation looks very intriguing. https://www.raptorengineering.com/TALOS/prerelease.php
and those have cpu wide ring0 escalation bug https://www.blackhat.com/docs/us-15/materials/us-15-Domas-Th...
i7 just says you're going to get the top of the performance (and price) list for a desktop/mobile processor.
My main system is still running a i7-2600 from over 5 years ago. That GTX 680 I have in there is still plenty fast. The upgrade question is: how pretty do I want Star Citizen to be?
It is still completely fine for everything I ask of it even against the much newer machine at work, with the upgrade to an SSD a while back it basically felt like a new machine.
