Messages in this thread | | | Subject | Re: [PATCH v2 2/2] KVM: PPC: Book3S HV: rework secure mem slot dropping | From | Laurent Dufour <> | Date | Wed, 22 Jul 2020 09:18:20 +0200 |
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Le 21/07/2020 à 23:37, Ram Pai a écrit : > On Tue, Jul 21, 2020 at 12:42:02PM +0200, Laurent Dufour wrote: >> When a secure memslot is dropped, all the pages backed in the secure device >> (aka really backed by secure memory by the Ultravisor) should be paged out >> to a normal page. Previously, this was achieved by triggering the page >> fault mechanism which is calling kvmppc_svm_page_out() on each pages. >> >> This can't work when hot unplugging a memory slot because the memory slot >> is flagged as invalid and gfn_to_pfn() is then not trying to access the >> page, so the page fault mechanism is not triggered. >> >> Since the final goal is to make a call to kvmppc_svm_page_out() it seems >> simpler to directly calling it instead of triggering such a mechanism. This > ^^ call directly instead of triggering.. > >> way kvmppc_uvmem_drop_pages() can be called even when hot unplugging a >> memslot. >> >> Since kvmppc_uvmem_drop_pages() is already holding kvm->arch.uvmem_lock, >> the call to __kvmppc_svm_page_out() is made. >> As __kvmppc_svm_page_out needs the vma pointer to migrate the pages, the >> VMA is fetched in a lazy way, to not trigger find_vma() all the time. In >> addition, the mmap_sem is help in read mode during that time, not in write > ^^ held > >> mode since the virual memory layout is not impacted, and >> kvm->arch.uvmem_lock prevents concurrent operation on the secure device. >> >> Cc: Ram Pai <linuxram@us.ibm.com> > > Reviewed-by: Ram Pai <linuxram@us.ibm.com>
Thanks for reviewing this series.
Regarding the wordsmithing, Paul, could you manage that when pulling the series?
Thanks, Laurent.
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