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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/30/24 22:21, Sean Christopherson wrote: > On Tue, Jul 30, 2024, Paolo Bonzini wrote: >> On 7/27/24 01:52, Sean Christopherson wrote: >>> Now that KVM no longer relies on an ugly heuristic to find its struct page >>> references, i.e. now that KVM can't get false positives on VM_MIXEDMAP >>> pfns, remove KVM's hack to elevate the refcount for pfns that happen to >>> have a valid struct page. In addition to removing a long-standing wart >>> in KVM, this allows KVM to map non-refcounted struct page memory into the >>> guest, e.g. for exposing GPU TTM buffers to KVM guests. >> >> Feel free to leave it to me for later, but there are more cleanups that >> can be made, given how simple kvm_resolve_pfn() is now: > > I'll revisit kvm_resolve_pfn(), Maxim also wasn't a fan of a similar helper that > existed in v11. FWIW kvm_resolve_pfn() is totally fine as an intermediate step. Just food for thought for possible follow-ups. >> Also, check_user_page_hwpoison() should not be needed anymore, probably >> not since commit 234b239bea39 ("kvm: Faults which trigger IO release the >> mmap_sem", 2014-09-24) removed get_user_pages_fast() from hva_to_pfn_slow(). > > Ha, I *knew* this sounded familiar. Past me apparently came to the same > conclusion[*], though I wrongly suspected a memory leak and promptly forgot to > ever send a patch. I'll tack one on this time around. As you prefer. Paolo