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    SubjectRe: [PATCH v2 12/13] KVM: x86: add SMM to the MMU role, support SMRAM address space


    On 09/06/2015 06:01, Xiao Guangrong wrote:
    >
    >
    > On 05/28/2015 01:05 AM, Paolo Bonzini wrote:
    >> This is now very simple to do. The only interesting part is a simple
    >> trick to find the right memslot in gfn_to_rmap, retrieving the address
    >> space from the spte role word. The same trick is used in the auditing
    >> code.
    >>
    >> The comment on top of union kvm_mmu_page_role has been stale forever,
    >
    > Fortunately, we have documented these fields in mmu.txt, please do it for
    > 'smm' as well. :)

    Right, done.

    >> + /*
    >> + * This is left at the top of the word so that
    >> + * kvm_memslots_for_spte_role can extract it with a
    >> + * simple shift. While there is room, give it a whole
    >> + * byte so it is also faster to load it from memory.
    >> + */
    >> + unsigned smm:8;
    >
    > I suspect if we really need this trick, smm is not the hottest filed in
    > this struct anyway.

    Note that after these patches it is used by gfn_to_rmap, and hence for
    example rmap_add.

    Paolo


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