> On 10/21/2018 06:57 PM, Ingo Molnar wrote: > > Does the CPU _ever_ look look at the PFN if the page is > > !_PAGE_PRESENT, for example speculatively? If yes then what is the > > recommended value for the pfn - zero perhaps? > > I'll never say never. :) > > For L1TF[1], we know the CPU did exactly this; it ignored the _PAGE_PRESENT > bit when fetching data from the L1. That's what is worked around with the gunk > in arch/x86/include/asm/pgtable-invert.h. > > I think Andi plugged the code in here at a low enough level in the page table > manipulation that pageattr.c should inherit it without doing anything explicit. > But, Sai, you might want to double-check this. > > 1. > https://www.intel.com/content/www/us/en/architecture-and- > technology/l1tf.html Sure! Dave. Thanks for the link. I will take a look at it. Regards, Sai
