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    SubjectRe: [PATCH Part2 v6 14/49] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled
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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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