Messages in this thread | | | Date | Wed, 16 Nov 2022 12:53:36 -0600 | Subject | Re: [PATCH Part2 v6 14/49] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled | From | "Kalra, Ashish" <> |
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On 11/16/2022 12:33 PM, Borislav Petkov wrote: > On Wed, Nov 16, 2022 at 12:01:11PM -0600, Kalra, Ashish wrote: >> Ok, so i will work on implementing this leaked pages list and put it on a >> sev/snp associated structure. > > See __sgx_sanitize_pages() and the poison list there, for an example. > >> Also to add here, we will actually get a not-present #PF instead of the RMP >> violation #PF on writing to these leaked pages, as these pages would have >> been removed from the kernel direct map. > > So if you do the list and still have the kernel raise a RMP fault for > those pages, traversing that list in the RMP handler to check whether > the page is there on it, should be a lot faster operation than doing the > #PF thing and removing them from the direct map. >
Actually, these host allocated pages would have already been removed from the kernel direct map, when they were transitioned to the firmware state. So actually the not-present #PF fault will happen on any read/write access to these leaked pages instead of the RMP violation #PF (not-present #PF has higher priority than RMP violation #PF).
If these pages cannot be reclaimed, they are unsafe to use and cannot be added back to the kernel direct map.
Thanks, Ashish
> And sorry for misleading you about UPM - we were thinking wrong > yesterday. > > Thx. >
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