AMD will reinstate memory encryption on Ryzen 9000 CPUs via BIOS update in July

rroboror about 3 hours ago 20 commentsRead Article on tomshardware.com

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Discussion (20 Comments)Read Original on HackerNews

theandrewbailey•40 minutes ago

> TSME isn't a critical security feature for most consumer desktops, as it protects against attacks where the attacker needs physical access to the device.

If you think it's hard to gain physical access to a consumer desktop, you're out of touch. Most desktops aren't locked inside a datacenter. Memory encryption is a valuable desktop (and laptop) security feature.

WillPostForFood•10 minutes ago

So my PC runs 5% slower because someone could break into my house to get physical access to decrypt memory? OK sure, but not my top concern, and a bad tradeoff for the lost performance. And not only fair, but completely accurate to describe TSME as non-critical for *most* consumer desktops. I'd go as far as to say useless and counter-productive for most, but not all, consumer desktops.

CivBase•23 minutes ago

You'd need physical access while it is running as the target is using it.

hnuser123456•16 minutes ago

When the threat model is physical security, henchmen are also a consideration.

Havoc•about 1 hour ago

I'm a little puzzled by the uproar given that all the oneline chatter seems to suggest nobody is using this. If this was AVX512 or something I could understand the give it back reaction...

stefanfisk•about 1 hour ago

Judging by the Reddit threads I saw, A LOT of people were upset even though it was clear that they had not idea what the feature actually provided beyond “encryption”. I’d guess that the majority assumed that the change would result in them basically having to “encryption” in affected AMD devices any more in some vague general sense.

Havoc•about 1 hour ago

Exactly. Thus far I've seen 1 person use it...and they seemed to believe it provides rowhammer benefit...so somewhat tangential

jdsully•about 1 hour ago

Physical hardware products shouldn't lose features after launch. If this was a "mistaken" feature which they suggested it was they should have disabled it on future chips.

RachelF•19 minutes ago

A lot of this has to do with segmenting the market into high-end and low-end products.

When they were the underdog to Intel, they gave away lots of premium features to beat Intel.

Since they got more popular, AMD has been taking away features, or not upgrading old tech, from their desktop/gaming CPUs: Their DDR5 interface is gimped, being slower than Intel now, and still limited to dual channel. Their chipset link is still PCIe 4x4 the same as two generations ago.

If you want these features now, you need a server product.

dijit•about 2 hours ago

People don’t like things being taken away, even if I don’t think many people are actually using this feature.

I don’t even think its exposed in most BIOS’s

dist-epoch•about 1 hour ago

And it does reduce memory speed by about 0.5-1%.

Modified3019•about 2 hours ago

They’ve been doing a bunch of stuff in agesa updates regarding memory stability lately, and also recently broke and fixed setting manual speed on DDR5 memory with ECC enabled (basically any setting higher or lower than 5200mhz or something was ignored).

I wonder if this was also something they just accidentally broke, or if it was an incompetent attempt at larger segmentation.

close04•about 1 hour ago

> I wonder if this was also something they just accidentally broke

Their statement suggests it was a calculated decision, reversed after public backlash. I greatly appreciate they listened to user feedback, but they shouldn't have done it secretly to begin with.

> Based on valuable community feedback, we will reinstate this option in an upcoming BIOS release in July.

jolmg•about 2 hours ago

Thought there were cases where other devices could have direct access to RAM (e.g. DMA, PCIe controllers outside the CPU, etc.). Wonder how that works in conjunction.

wmf•about 1 hour ago

The encryption/decryption is done in the memory controller so it doesn't matter where the access is coming from.

porridgeraisin•about 1 hour ago

There are many ways it can work depending on the cpu:

1. No dma, instead you use bounce buffers and the cpu manually encrypts and decrypts on behalf of the pcie

2. The IOMMU sets certain pages as unencrypted and ensures the pcie only accesses those pages and that part of ram alone is now not encrypted.

3. Newer pcie devices use the TDISP(handshake) and IDE(aes gcm hardware module related stuff) protocols to do encrypted communication with the CPUs PCIe root hub, where this functionality is called TIO i.e trusted io on amd and TX connect on intel. As far as nvidia GPUs go which is where I have used this, H100 onwards have the feature. Only server xeons and turins etc support this feature on the cpu side. I think some server SSDs do too. Here you get full encryption full DMA at full bandwidth.

roboror•about 3 hours ago

Full title: AMD will reinstate memory encryption on Ryzen 9000 CPUs through a BIOS update in July — TSME is coming back after 'valuable community feedback'

helterskelter•about 2 hours ago

Good. Intel's equivalent processors have this feature and BS market segmentation is the kind of thing that AMD was historically against. Even if something wasn't officially supported, they didn't go out of their way to prevent its use.

ChrisArchitect•37 minutes ago

Discussion on the previous development:

AMD silently removes memory encryption from consumer Ryzen CPUs

https://news.ycombinator.com/item?id=48582320

varispeed•about 1 hour ago

I wish they could enable use of non-ECC ram on Threadrippers.

opengrass•about 2 hours ago

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