On 01/29/2013 02:50 PM, Gleb Natapov wrote: > 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? Sharing memory between different guests. > >> 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? Simply disallow READONLY flag changing. -- 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
