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. So, i guess we can do the simple fix first. -- 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
