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SubjectRe: [RFCv2 15/16] KVM: Unmap protected pages from direct mapping
Date
On Tue, 2020-10-20 at 09:18 +0300, Kirill A. Shutemov wrote:
> If the protected memory feature enabled, unmap guest memory from
> kernel's direct mappings.
>
> Migration and KSM is disabled for protected memory as it would
> require a
> special treatment.
>
So do we care about this scenario where a malicious userspace causes a
kernel oops? I'm not sure if it's prevented somehow.

CPU0 (exercising other kernel functionality) CPU1
mark page shared
page = get_user_pages(!FOLL_KVM)
mark page private
kmap(page)
access unmapped page and oops

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