AMD will reinstate memory encryption on Ryzen 9000 CPUs via BIOS update in July(www.tomshardware.com)
116 pointsby roboror5 hours ago10 comments
  • theandrewbailey2 hours 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.

    • WillPostForFood2 hours 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.
      • futuraperditaan hour ago
        So you turn it off by default in BIOS and allow those that feel it's useful to them to enable it, and you solve for both sides of the problem.
      • 2 hours ago
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    • cwilluan hour ago
      If the bad guys have physical access to my consumer desktop, I'm already well and truly fucked.
    • rr808an hour ago
      The last few companies have all had desktops in datacenters with the local PC just a virtual terminal.
    • CivBase2 hours ago
      You'd need physical access while it is running as the target is using it.
      • hnuser1234562 hours ago
        When the threat model is physical security, henchmen are also a consideration.
  • Havoc3 hours 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...
    • saghm2 hours ago
      I think it's that principle. CPU firmware upgrades are not supposed be used for things like this, and if it became normal to use them for removing features, it would just lead to people not updating the firmware at all, and that's not a good scenario for anyone.
    • jdsully3 hours 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.
      • RachelF2 hours 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.

        • saghm2 hours ago
          None of that is a good rationale for patching the firmware to retroactively remove things from devices that were sold years ago. It's an abuse of a mechanism that's ostensibly meant for security fixes and maybe perf improvements, which is a dangerous game because it incentivizes people to just not update the firmware at all, which is a worse scenario for both parties than just resolving to not include the feature in CPUs going forward if it's such a huge loss to include it.
    • stefanfisk3 hours 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.
      • Havoc3 hours ago
        Exactly. Thus far I've seen 1 person use it...and they seemed to believe it provides rowhammer benefit...so somewhat tangential
  • dijit4 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-epoch3 hours ago
      And it does reduce memory speed by about 0.5-1%.
  • roboror5 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'
  • Modified30193 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.

    • close043 hours 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.

    • KennyBlanken2 hours ago
      We're talking about a company that five generations into its processor family still hasn't been able to figure out how to have USB work properly and reliably.

      AMD Adrenalin, their software that manages things video/GPU features like clip saving, performance settings, game optimizations, update monitoring, performance overlaying, etc - is so fucking bad that if your mouse is set to a refresh rate over 500hz, it is virtually unusable because the mouse cursor takes half a second to respond to inputs. This is running on a card one step down from the flagship, current generation.

      Don't even get me started about ROCm on Windows.

  • jolmg3 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.
    • wmf3 hours ago
      The encryption/decryption is done in the memory controller so it doesn't matter where the access is coming from.
    • porridgeraisin3 hours 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.

  • helterskelter3 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.
  • ChrisArchitect2 hours ago
    Discussion on the previous development:

    AMD silently removes memory encryption from consumer Ryzen CPUs

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

  • varispeed3 hours ago
    I wish they could enable use of non-ECC ram on Threadrippers.
    • timschmidt2 hours ago
      I wish we'd stop pretending that non-ECC ram is ok on any platform.
  • opengrass4 hours ago
    Rust developer: "Ba da Ba Ba Ba"
    • saghm2 hours ago
      Sure, as long as your OS is written in Rust (and doesn't use any unsafe)