Re: [RFCv2 15/16] KVM: Unmap protected pages from direct mapping

[Edgecombe, Rick P]

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