[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] 答复: [Xen-devel] shadow_clean_dirty_bitmap's another solution
Thanks for your advice. I am sorry my code was not complete in last mail. I forgot to mention that I was looking in sl2es because I wanted to only walk all the in-use L1 shadow page tables. Those not in-use L1 shadow page tables are not walked. That's because when a L1 shadow page table is selected to be in-use, the entries will be propagated from the guest page table again. Then, the R/W bit will be cleared because of log dirty mode. Just as shadow_blow_tables, it only blows the in-use shadow page tables. Others in the hash table are not blew down. Am I right? Yes, my code is too cautious, because I have tried too many times to remove my faults. Unfortunately, I am not sure about my solution. -----邮件原件----- 发件人: Tim Deegan [mailto:Tim.Deegan@xxxxxxxxxx] 发送时间: 2009年6月24日 17:16 收件人: zhujun 抄送: xen-devel@xxxxxxxxxxxxxxxxxxx 主题: Re: [Xen-devel] shadow_clean_dirty_bitmap's another solution At 10:08 +0100 on 24 Jun (1245838118), zhujun wrote: > Hi, > When doing live migration, the shadow code is translated to log dirty mode. However, in the shadow_clean_dirty_bitmap function, all the in-use shadow page tables are blew down. I think it is too crude, just as the comment of the function says. I am trying to find a better solution, but it does not succeeds. Would you please help me check my source code and give me some suggestions? My current solution is walking all the in-use L1 shadow page tables and clearing each L1 entry?s R/W bit if it has set. > I don?t know whether it is enough to remove these R/W bits for live migration. If not, how to make all the pages of a PV domain read-only again? Thanks very much! > My source code is here. > > sl1mfn = shadow_l2e_get_mfn(*sl2e); Stop right there! :) Why are you looking in sl2es? You need to make _all_ the sl1es read-only for this to work. You should be using hash_foreach() to walk through every l1 shadow. Have a look at sh_remove_all_mappings for an example of code that walks every sl1 table. Also your code below seems a bit too cautious: it should be OK to just check for_PAGE_PRESENT and _PAGE_RW and then clean _PAGE_RW. Cheers, Tim. > if ( mfn_valid(sl1mfn) ) > { > SHADOW_FOREACH_L1E(sl1mfn, sl1e, 0, 0, { > flags = shadow_l1e_get_flags(*sl1e); > target_mfn = shadow_l1e_get_mfn(*sl1e); > if(mfn_valid(target_mfn)) > { > pg = mfn_to_page(target_mfn); > if ((pg != NULL) || ((pg->u.inuse.type_info & PGT_type_mask) == PGT_writable_page)) > { > if ((flags & _PAGE_PRESENT) && (flags & _PAGE_RW)) > { > shadow_l1e_t ro_sl1e = shadow_l1e_remove_flags(*sl1e, _PAGE_RW); > (void) shadow_set_l1e(v, sl1e, ro_sl1e, sl1mfn); > } > } > } > }); > } > > > zhujun > Content-Description: ATT00001.txt > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxxxxxxxx > http://lists.xensource.com/xen-devel -- Tim Deegan <Tim.Deegan@xxxxxxxxxx> Principal Software Engineer, Citrix Systems (R&D) Ltd. [Company #02300071, SL9 0DZ, UK.] _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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