Move INVLPG to pmap_quick_enter_page() from pmap_quick_remove_page().
If processor prefetches neighboring TLB entries to the one being accessed (as some have been reported to do), then the spin lock does not prevent the situation described in the "AMD64 Architecture Programmer's Manual Volume 2: System Programming" rev. 3.23, "7.3.1 Special Coherency Considerations". Reported and reviewed by: alc Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D37770
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@ -10423,6 +10423,13 @@ pmap_quick_enter_page(vm_page_t m)
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return (PHYS_TO_DMAP(paddr));
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mtx_lock_spin(&qframe_mtx);
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KASSERT(*vtopte(qframe) == 0, ("qframe busy"));
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/*
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* Since qframe is exclusively mapped by us, and we do not set
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* PG_G, we can use INVLPG here.
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*/
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invlpg(qframe);
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pte_store(vtopte(qframe), paddr | X86_PG_RW | X86_PG_V | X86_PG_A |
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X86_PG_M | pmap_cache_bits(kernel_pmap, m->md.pat_mode, 0));
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return (qframe);
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@ -10435,14 +10442,6 @@ pmap_quick_remove_page(vm_offset_t addr)
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if (addr != qframe)
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return;
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pte_store(vtopte(qframe), 0);
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/*
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* Since qframe is exclusively mapped by
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* pmap_quick_enter_page() and that function doesn't set PG_G,
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* we can use INVLPG here.
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*/
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invlpg(qframe);
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mtx_unlock_spin(&qframe_mtx);
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}
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