On Wed, Apr 03, 2024 at 02:51:59PM +0200, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > On Wed, Apr 3, 2024 at 12:58 AM Isaku Yamahata <isaku.yamahata@xxxxxxxxx> wrote: > > I think TDX can use it with slight change. Pass vcpu instead of KVM, page pin > > down and mmu_lock. TDX requires non-leaf Secure page tables to be populated > > before adding a leaf. Maybe with the assumption that vcpu doesn't run, GFN->PFN > > relation is stable so that mmu_lock isn't needed? What about punch hole? > > > > The flow would be something like as follows. > > > > - lock slots_lock > > > > - kvm_gmem_populate(vcpu) > > - pin down source page instead of do_memcopy. > > Both pinning the source page and the memcpy can be done in the > callback. I think the right thing to do is: > > 1) eliminate do_memcpy, letting AMD code taking care of > copy_from_user. > > 2) pass to the callback only gfn/pfn/src, where src is computed as > > args->src ? args->src + i * PAGE_SIZE : NULL > > If another architecture/vendor needs do_memcpy, they can add > something like kvm_gmem_populate_copy. > > > - get pfn with __kvm_gmem_get_pfn() > > - read lock mmu_lock > > - in the post_populate callback > > - lookup tdp mmu page table to check if the table is populated. > > lookup only version of kvm_tdp_mmu_map(). > > We need vcpu instead of kvm. > > Passing vcpu can be done using the opaque callback argument to > kvm_gmem_populate. > > Likewise, the mmu_lock can be taken by the TDX post_populate > callback. Yes, it should work. Let me give it a try. -- Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
