Messages in this thread | | | Date | Mon, 12 Nov 2012 21:12:23 -0200 | From | Marcelo Tosatti <> | Subject | Re: [PATCH 2/5] KVM: MMU: simplify mmu_set_spte |
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On Mon, Nov 05, 2012 at 08:10:08PM +0800, Xiao Guangrong wrote: > In order to detecting spte remapping, we can simply check whether the > spte has already been pointing to the pfn even if the spte is not the > last spte for middle spte is pointing to the kernel pfn which can not > be mapped to userspace > > Also, update slot and stat.lpages iff the spte is not remapped > > Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> > --- > arch/x86/kvm/mmu.c | 40 +++++++++++++--------------------------- > 1 files changed, 13 insertions(+), 27 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 692ebb1..4ea731e 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -2420,8 +2420,7 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, > pfn_t pfn, bool speculative, > bool host_writable) > { > - int was_rmapped = 0; > - int rmap_count; > + bool was_rmapped = false; > > pgprintk("%s: spte %llx access %x write_fault %d" > " user_fault %d gfn %llx\n", > @@ -2429,25 +2428,13 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, > write_fault, user_fault, gfn); > > if (is_rmap_spte(*sptep)) { > - /* > - * If we overwrite a PTE page pointer with a 2MB PMD, unlink > - * the parent of the now unreachable PTE. > - */ > - if (level > PT_PAGE_TABLE_LEVEL && > - !is_large_pte(*sptep)) { > - struct kvm_mmu_page *child; > - u64 pte = *sptep; > + if (pfn != spte_to_pfn(*sptep)) { > + struct kvm_mmu_page *sp = page_header(__pa(sptep)); > > - child = page_header(pte & PT64_BASE_ADDR_MASK); > - drop_parent_pte(child, sptep); > - kvm_flush_remote_tlbs(vcpu->kvm);
How come its safe to drop this case?
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