Messages in this thread | | | Date | Sat, 21 Apr 2012 11:30:55 +0800 | From | Xiao Guangrong <> | Subject | Re: [PATCH v3 4/9] KVM: MMU: introduce SPTE_ALLOW_WRITE bit |
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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).
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