On 1/12/24 21:07, Borislav Petkov wrote:

On Fri, Jan 12, 2024 at 12:00:01PM -0800, Dave Hansen wrote:

quoted

On 12/30/23 08:19, Michael Roth wrote:

quoted

If the kernel uses a 2MB directmap mapping to write to an address, and
that 2MB range happens to contain a 4KB page that set to private in the
RMP table, that will also lead to a page-fault exception.

I thought we agreed long ago to just demote the whole direct map to 4k
on kernels that might need to act as SEV-SNP hosts.  That should be step
one and this can be discussed as an optimization later.

What would be the disadvantage here? Higher TLB pressure when running
kernel code I guess...

Yeah and last LSF/MM we concluded that it's not as a big disadvantage as we
previously thought https://lwn.net/Articles/931406/