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    SubjectRe: [RFCv2 15/16] KVM: Unmap protected pages from direct mapping
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    On 10/20/20 7:18 AM, David Hildenbrand wrote:
    > On 20.10.20 08:18, Kirill A. Shutemov wrote:
    >> If the protected memory feature enabled, unmap guest memory from
    >> kernel's direct mappings.
    >
    > Gah, ugly. I guess this also defeats compaction, swapping, ... oh gosh.
    > As if all of the encrypted VM implementations didn't bring us enough
    > ugliness already (SEV extensions also don't support reboots, but can at
    > least kexec() IIRC).

    SEV does support reboot. SEV-ES using Qemu doesn't support reboot because
    of the way Qemu resets the vCPU state. If Qemu could relaunch the guest
    through the SEV APIs to reset the vCPU state, then a "reboot" would be
    possible.

    SEV does support kexec, SEV-ES does not at the moment.

    Thanks,
    Tom

    >
    > Something similar is done with secretmem [1]. And people don't seem to
    > like fragmenting the direct mapping (including me).
    >
    > [1] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flkml.kernel.org%2Fr%2F20200924132904.1391-1-rppt%40kernel.org&data=04%7C01%7Cthomas.lendacky%40amd.com%7Cb98a5033da37432131b508d874f25194%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637387931403890525%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=BzC%2FeIyOau7BORuUY%2BaiRzYZ%2BOAHANvBDcmV9hpkrts%3D&reserved=0
    >

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