News: 0001552074

  ARM Give a man a fire and he's warm for a day, but set fire to him and he's warm for the rest of his life (Terry Pratchett, Jingo)

AMD Preps Linux Support For User CPUID Faulting

([AMD] 3 Hours Ago AMD CPUID Faulting)


While Intel has supported CPUID Faulting on processors going back to Ivy Bridge and supported this feature in the Linux kernel since early 2017, only now the AMD support is being wired up and making use of the existing Intel code paths.

CPUID Faulting is a feature for having the processor fault on attempts to execute a CPUID instruction above privilege level zero (CPL 0 / Ring 0). In turn this can be used for a tracer to emulate the CPUID instruction and similar use-cases like by some VMMs/hypervisors for trapping user-space CPUID instructions.

While long supported by Intel CPUs with Ivy Bridge in 2012 and the Linux kernel since 2017, only last week was an AMD patch posted for CPUID Faulting support.

[1]This patch introduces CPUID faulting support on AMD using the same user interface as Intel. The patch doesn't specify what generations of AMD CPUs are capable of natively supporting User CPUID Faulting.



[1] https://lore.kernel.org/lkml/20250528213105.1149-1-bp@kernel.org/


phoronix

You can always tell the Christmas season is here when you start getting
incredibly dense, tinfoil-and-ribbon- wrapped lumps in the mail. Fruitcakes
make ideal gifts because the Postal Service has been unable to find a way to
damage them. They last forever, largely because nobody ever eats them. In
fact, many smart people save the fruitcakes they receive and send them back
to the original givers the next year; some fruitcakes have been passed back
and forth for hundreds of years.

The easiest way to make a fruitcake is to buy a darkish cake, then pound
some old, hard fruit into it with a mallet. Be sure to wear safety glasses.
-- Dave Barry, "Simple, Homespun Gifts"