On 10/05/2010 01:59 AM, Marcelo Tosatti wrote:
Yep, the drawback is the unnecessary write fault. What i have here is:--- kvm.orig/virt/kvm/kvm_main.c +++ kvm/virt/kvm/kvm_main.c @@ -827,7 +827,7 @@ unsigned long gfn_to_hva(struct kvm *kvm } EXPORT_SYMBOL_GPL(gfn_to_hva); -pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn) +pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn, int *writable) { struct page *page[1]; unsigned long addr; @@ -842,8 +842,16 @@ pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t return page_to_pfn(bad_page); } + *writable = 1; npages = get_user_pages_fast(addr, 1, 1, page); + /* attempt to map read-only */ + if (unlikely(npages != 1)) { + npages = get_user_pages_fast(addr, 1, 0, page); + if (npages == 1) + *writable = 0; + } + if (unlikely(npages != 1)) { struct vm_area_struct *vma; Can rebase and resend, if you'd like.
That will work for me but not for ksm. I guess it's good to get things going, so please to post it.
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