Messages in this thread |  | | Date | Fri, 12 Jan 2024 14:28:13 -0600 | | Subject | Re: [PATCH v1 11/26] x86/sev: Invalidate pages from the direct map when adding them to the RMP table | | From | Tom Lendacky <> |
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On 1/12/24 14:07, Borislav Petkov wrote: > On Fri, Jan 12, 2024 at 12:00:01PM -0800, Dave Hansen wrote: >> On 12/30/23 08:19, Michael Roth wrote: >>> 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 there was also a desire to remove the direct map for any pages assigned to a guest as private, not just the case that the comment says. So updating the comment would probably the best action.
>> >> 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.
Won't this accomplish that without actually demoting a lot of long-live kernel related mappings that would never be demoted? I don't think we need to demote the whole mapping to 4K.
Thanks, Tom
> > What would be the disadvantage here? Higher TLB pressure when running > kernel code I guess... >
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