On Tue, Jan 29, 2013 at 11:06:43AM +0800, Xiao Guangrong wrote: > On 01/28/2013 06:59 PM, Gleb Natapov wrote: > > On Fri, Jan 25, 2013 at 11:28:40AM +0800, Xiao Guangrong wrote: > >> On 01/25/2013 09:17 AM, Takuya Yoshikawa wrote: > >>> On Thu, 24 Jan 2013 15:03:57 -0700 > >>> Alex Williamson <alex.williamson@xxxxxxxxxx> wrote: > >>> > >>>> A couple patches to make KVM IOMMU support honor read-only mappings. > >>>> This causes an un-map, re-map when the read-only flag changes and > >>>> makes use of it when setting IOMMU attributes. Thanks, > >>> > >>> Looks good to me. > >>> > >>> I think I can naturally update my patch after this gets merged. > >>> > >> > >> Please wait. > >> > >> The commit c972f3b1 changed the write-protect behaviour - it does > >> wirte-protection only when dirty flag is set. > >> [ I did not see this commit when we discussed the problem before. ] > >> > >> Further more, i notice that write-protect is not enough, when do sync > >> shadow page: > >> > >> FNAME(sync_page): > >> > >> host_writable = sp->spt[i] & SPTE_HOST_WRITEABLE; > >> > >> set_spte(vcpu, &sp->spt[i], pte_access, > >> PT_PAGE_TABLE_LEVEL, gfn, > >> spte_to_pfn(sp->spt[i]), true, false, > >> host_writable); > >> > >> It sets spte based on the old value that means the readonly flag check > >> is missed. We need to call kvm_arch_flush_shadow_all under this case. > > Why not just disallow changing memory region KVM_MEM_READONLY flag > > without deleting the region? > > It will introduce some restriction when VM-sharing-mem is being implemented, > but we need to do some optimization for it, at least, properly write-protect > readonly pages (fix sync_page()) instead of zap_all_page. > What is VM-sharing-mem? > So, i guess we can do the simple fix first. > By simple fix you mean calling kvm_arch_flush_shadow_all() on READONLY flag change? -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
