AMD Zen: Exploited Before Release

[grarpamp]

https://www.bleepingcomputer.com/news/hardware/researchers-point-out-theoretical-security-flaws-in-amds-upcoming-zen-cpu/
http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2013/12/AMD_Memory_Encryption_Whitepaper_v7-Public.pdf
https://arxiv.org/pdf/1612.01119v1.pdf

The security protocol that governs how virtual machines share data on
a host system powered by AMD Zen processors has been found to be
insecure, at least in theory, according to two German researchers. The
technology, called Secure Encrypted Virtualization (SEV), is designed
to encrypt parts of the memory shared by different virtual machines on
cloud servers. AMD, who plans to ship SEV with its upcoming line of
Zen processors, has published the technical documentation for the SEV
technology this past April. The German researchers have analyzed the
design of SEV, using this public documentation, and said they managed
to identify three attack channels, which work, at least in theory.
[In a technical paper released over the past weekend, the researchers
described their attacks:] "We show how a malicious hypervisor can
force the guest to perform arbitrary read and write operations on
protected memory. We describe how to completely disable any SEV memory
protection configured by the tenant. We implement a replay attack that
uses captured login data to gain access to the target system by solely
exploiting resource management features of a hypervisor." AMD is
scheduled to ship SEV with the Zen processor line in the first quarter
of 2017.




http://hothardware.com/news/amd-to-attack-performance-desktop-market-with-ryzen-more-zen-architecture-details-revealed
http://hothardware.com/reviews/amd-unveils-additional-zen-processor-details-and-performance-versus-broadwell-e
http://hothardware.com/news/cern-engineer-leaks-amd-zen-architecture-details-claiming-40-percent-increase-in-ipc-up-to-32-cores
AMD has disclosed that one of the high-end options in the initial
RYZEN line-up will feature 8 cores (16 threads with SMT) and at
minimum a 3.4 GHz base clock, with higher turbo frequencies. That
processor will also be outfitted with 20MB of cache -- 4MB of L2 and
16MB of L3 -- and it will be infused with what AMD is calling SenseMI
technology. SenseMI is essentially fancy branding for the updated
branch predictor, prefetcher, and power and control logic in Zen.
AMD's upcoming AM4 platform for RYZEN will be outfitted with all of
the features expected of a modern PC enthusiast platform. AM4
motherboards will use DDR4 memory and feature PCIe Gen 3 connectivity,
and support for USB 3.1 Gen 2, NVMe, and SATA Express. Performance
demos of RYZEN shown to members of the press pit a stock Intel Core
i7-6900K (3.2GHz base, 3.7GHz turbo) with Turbo Boost that was enabled
on the 6900K, versus RYZEN with boost disabled running at 3.4GHz flat.
In the demo, the RYZEN system outpaced the Core i7-6900K by a few
seconds.
AMD has been talking about the claimed 40% IPC (Instructions Per
Clock) improvement of its forthcoming Zen processor versus the
company's existing Excavator core for ages.AMD claims to have achieved
that 40 percent IPC uplift with a newly-designed, higher-performance
branch prediction and a micro-op cache for more efficient issuing of
operations. The instruction schedule windows have been increased by
75% and issue-width and execution resources have been increased by
50%. The end result of these changes is higher single-threaded
performance, through better instruction level parallelism. Zen's
pre-fetcher is also vastly improved. There is 8MB of shared L3 cache
on board now, a unified L2 cache for both instruction and data, and
separate, low-latency L1 instruction and data caches. The new
archicture offers up to 5x the cache bandwidth to the cores versus
previous-gen offerings. However, after all the specsmanship was out of
the way, AMD actually showcased a benchmark run of an 8-core Zen
Summit Ridge procesor versus Intel's Broadwell-E 8-core chip, both
running at 3GHz and processing a Blender rending workload. In the
demo, the 8-core Zen CPU actually outpaced Intel's chip by a hair.