forked from Minki/linux
KVM: MMU: Introduce drop_spte()
When we call rmap_remove(), we (almost) always immediately follow it by an __set_spte() to a nonpresent pte. Since we need to perform the two operations atomically, to avoid losing the dirty and accessed bits, introduce a helper drop_spte() and convert all call sites. The operation is still nonatomic at this point. Signed-off-by: Avi Kivity <avi@redhat.com>
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dd180b3e90
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@ -658,6 +658,12 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
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}
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}
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static void drop_spte(struct kvm *kvm, u64 *sptep, u64 new_spte)
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{
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rmap_remove(kvm, sptep);
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__set_spte(sptep, new_spte);
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}
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static u64 *rmap_next(struct kvm *kvm, unsigned long *rmapp, u64 *spte)
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{
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struct kvm_rmap_desc *desc;
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@ -722,9 +728,9 @@ static int rmap_write_protect(struct kvm *kvm, u64 gfn)
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BUG_ON((*spte & (PT_PAGE_SIZE_MASK|PT_PRESENT_MASK)) != (PT_PAGE_SIZE_MASK|PT_PRESENT_MASK));
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pgprintk("rmap_write_protect(large): spte %p %llx %lld\n", spte, *spte, gfn);
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if (is_writable_pte(*spte)) {
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rmap_remove(kvm, spte);
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drop_spte(kvm, spte,
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shadow_trap_nonpresent_pte);
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--kvm->stat.lpages;
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__set_spte(spte, shadow_trap_nonpresent_pte);
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spte = NULL;
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write_protected = 1;
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}
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@ -744,8 +750,7 @@ static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
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while ((spte = rmap_next(kvm, rmapp, NULL))) {
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BUG_ON(!(*spte & PT_PRESENT_MASK));
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rmap_printk("kvm_rmap_unmap_hva: spte %p %llx\n", spte, *spte);
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rmap_remove(kvm, spte);
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__set_spte(spte, shadow_trap_nonpresent_pte);
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drop_spte(kvm, spte, shadow_trap_nonpresent_pte);
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need_tlb_flush = 1;
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}
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return need_tlb_flush;
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@ -767,8 +772,7 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
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rmap_printk("kvm_set_pte_rmapp: spte %p %llx\n", spte, *spte);
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need_flush = 1;
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if (pte_write(*ptep)) {
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rmap_remove(kvm, spte);
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__set_spte(spte, shadow_trap_nonpresent_pte);
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drop_spte(kvm, spte, shadow_trap_nonpresent_pte);
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spte = rmap_next(kvm, rmapp, NULL);
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} else {
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new_spte = *spte &~ (PT64_BASE_ADDR_MASK);
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@ -1464,7 +1468,8 @@ static void kvm_mmu_page_unlink_children(struct kvm *kvm,
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} else {
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if (is_large_pte(ent))
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--kvm->stat.lpages;
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rmap_remove(kvm, &pt[i]);
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drop_spte(kvm, &pt[i],
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shadow_trap_nonpresent_pte);
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}
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}
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pt[i] = shadow_trap_nonpresent_pte;
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@ -1868,9 +1873,8 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
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if (level > PT_PAGE_TABLE_LEVEL &&
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has_wrprotected_page(vcpu->kvm, gfn, level)) {
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ret = 1;
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rmap_remove(vcpu->kvm, sptep);
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spte = shadow_trap_nonpresent_pte;
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goto set_pte;
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drop_spte(vcpu->kvm, sptep, shadow_trap_nonpresent_pte);
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goto done;
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}
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spte |= PT_WRITABLE_MASK;
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@ -1902,6 +1906,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
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set_pte:
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__set_spte(sptep, spte);
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done:
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return ret;
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}
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@ -1938,8 +1943,7 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
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} else if (pfn != spte_to_pfn(*sptep)) {
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pgprintk("hfn old %lx new %lx\n",
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spte_to_pfn(*sptep), pfn);
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rmap_remove(vcpu->kvm, sptep);
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__set_spte(sptep, shadow_trap_nonpresent_pte);
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drop_spte(vcpu->kvm, sptep, shadow_trap_nonpresent_pte);
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kvm_flush_remote_tlbs(vcpu->kvm);
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} else
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was_rmapped = 1;
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@ -2591,7 +2595,7 @@ static void mmu_pte_write_zap_pte(struct kvm_vcpu *vcpu,
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pte = *spte;
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if (is_shadow_present_pte(pte)) {
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if (is_last_spte(pte, sp->role.level))
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rmap_remove(vcpu->kvm, spte);
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drop_spte(vcpu->kvm, spte, shadow_trap_nonpresent_pte);
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else {
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child = page_header(pte & PT64_BASE_ADDR_MASK);
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mmu_page_remove_parent_pte(child, spte);
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@ -353,8 +353,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
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}
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if (is_large_pte(*sptep)) {
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rmap_remove(vcpu->kvm, sptep);
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__set_spte(sptep, shadow_trap_nonpresent_pte);
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drop_spte(vcpu->kvm, sptep, shadow_trap_nonpresent_pte);
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kvm_flush_remote_tlbs(vcpu->kvm);
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}
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@ -516,12 +515,13 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva)
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pte_gpa += (sptep - sp->spt) * sizeof(pt_element_t);
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if (is_shadow_present_pte(*sptep)) {
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rmap_remove(vcpu->kvm, sptep);
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if (is_large_pte(*sptep))
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--vcpu->kvm->stat.lpages;
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drop_spte(vcpu->kvm, sptep,
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shadow_trap_nonpresent_pte);
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need_flush = 1;
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}
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__set_spte(sptep, shadow_trap_nonpresent_pte);
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} else
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__set_spte(sptep, shadow_trap_nonpresent_pte);
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break;
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}
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@ -637,12 +637,11 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
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!is_present_gpte(gpte) || !(gpte & PT_ACCESSED_MASK)) {
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u64 nonpresent;
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rmap_remove(vcpu->kvm, &sp->spt[i]);
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if (is_present_gpte(gpte) || !clear_unsync)
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nonpresent = shadow_trap_nonpresent_pte;
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else
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nonpresent = shadow_notrap_nonpresent_pte;
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__set_spte(&sp->spt[i], nonpresent);
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drop_spte(vcpu->kvm, &sp->spt[i], nonpresent);
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continue;
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}
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