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Discussion (36 Comments)Read Original on HackerNews
Whilst I hate companies paying engineers to make things worse just to segment their market; I am not really seeing this as an important feature outside the data-center? If an evil-maid has hardware access they hack the USB and/or PCI not the RAM surely?
Probably not from a legal perspective, but morally yes. Apple cause batterygate with good intentions but sneakily. Not being transparent is what shot them in the foot. AMD didn't learn anything or think this is small-time so no blowback (sadly they might be right).
And there's been talk that now the so-called "AI companies" will start using more CPUs as well, due to "personal agentic agents", so I hope that people won't be priced out of CPUs too...
A feature that was possibly accidentally enabled on consumer chips is now being disabled. I would guess that the number of owners of consumer chips who also relied on them for encryption is exceedingly small.
The primary concern persists. The manufacturer has an exceptional amount of control of the state of your CPU most of which you cannot change and an unknown chunk of which you cannot even see. We are sort of playing in a fools paradise.
They either have that control or they don't.
So it's quite possible they were doing the same with TSME, and either made a rude marketing decision that the people using it on consumer chips would probably pay for PRO chips if they were prevented from doing so, or kept getting people attempting to RMA the chips for a feature they never said worked on them not working, or there's some systemic flaw in the consumer chip's implementation that they didn't feel like trying to qualify fixing versus just killing the not-guaranteed support.
Hard to guess without more data than just them going silent about it.
But yeah 95% of the consumer market don't care about this and it's only adding unnecessary costs
You have to store the encryption key in CPU registers and ensure it's not saved to RAM during task switching or power suspend operations. Tresor used x86-specific debug registers for it, but you could potentially use unused SIMD registers if you masked-off the CPUID bits for them and disabled them for access by user-space.
But securing against attacks from a hostile hypervisor or a server provider needs more than just memory encryption, because they can intercept any part of the boot process and control the hardware/firmware that can lie to your kernel.
To counter that you'd need something like AMD SEV(ES/SNP) with measured boot and remote attestation to switch the only thing you trust to the CPU manufacturer (best you can do IMO).
For most consumer users, RAM encryption primarily adds power consumption and heat generation while providing little practical benefit. They simply don't face many of the threat vectors and attack scenarios that certain industries and enterprise environments must contend with.
I also believe that a strong reason that Optane pdimm's failed, was that it was only available on enterprise servers so hackers didn't get a chance to play with it and build software that took advantage of this special hardware.
Just look at how specialized Infiniband is, even though its awesome and has some great use cases. If it was a commodity tech, there would be 100x times more applications/software that took advantage of it.
this is approximately the same discussion as with ECC RAM: the benefits vastly outweigh the slight performance loss and die area increases.
Memory encryption, on the other hand, provides absolutely no benefit to 99.999% of users. If you consider yourself to be such a high value target that you suspect someone might gain physical access to your hardware without your knowledge and carry out extremely sophisticated hardware attacks to extract your data, you are a tiny minority and it makes sense that such niche protections would require buying specialized hardware. Even then, the odds of such an attack being chosen instead of a far less sophisticated software-based approach are also tiny.
Of course, if the hardware itself supports the feature and AMD simply decided to disable it, that's still a shitty thing to do, but let's not pretend that it is in any way comparable to ECC.
There are many people, myself included who opt to use security features like this. All this does is reduce security for folks without any legitimate reason. “Power consumption” is absolutely not a valid excuse to completely disable it.
I’ve been a fan of AMD for a while now but they’re really jumping the shark these days. It’s a real shit situation we’re all in because of the lack of competition in consumer CPUs. I can only hope things like RISCV take off sooner than later.