On 04/21/2012 07:22 AM, Marcelo Tosatti wrote: > On Sat, Apr 21, 2012 at 11:30:55AM +0800, Xiao Guangrong wrote: > > On 04/21/2012 05:39 AM, Marcelo Tosatti wrote: > > > > > > >> @@ -1177,9 +1178,8 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, > > >> unsigned long *rmapp, > > >> new_spte = *sptep & ~PT64_BASE_ADDR_MASK; > > >> new_spte |= (u64)new_pfn << PAGE_SHIFT; > > >> > > >> - new_spte &= ~PT_WRITABLE_MASK; > > >> - new_spte &= ~SPTE_HOST_WRITEABLE; > > >> - new_spte &= ~shadow_accessed_mask; > > >> + new_spte &= ~(PT_WRITABLE_MASK | > > >> SPTE_HOST_WRITEABLE | > > >> + shadow_accessed_mask | > > >> SPTE_ALLOW_WRITE); > > > > > > Each bit should have a distinct meaning. Here the host pte is being > > > write-protected, which means only the SPTE_HOST_WRITEABLE bit > > > should be cleared. > > > > > > Hmm, it is no problem if SPTE_ALLOW_WRITE is not cleared. > > > > But the meaning of SPTE_ALLOW_WRITE will become strange: we will see a > > spte with spte.SPTE_ALLOW_WRITE = 1 (means the spte is writable on host > > and guest) and spte.SPTE_HOST_WRITEABLE = 0 (means the spte is read-only > > on host). > > You are combining gpte writable bit, and host pte writable bit (which > are separate and independent of each other) into one bit. > > SPTE_HOST_WRITEABLE already indicates whether the host pte is writable > or not.
Maybe we should rename SPTE_ALLOW_WRITE to SPTE_NOT_SHADOWED (or SPTE_SHADOWED with the opposite meaning). Alternatively, SPTE_MMU_WRITEABLE (complements SPTE_HOST_WRITEABLE). -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
