KVM: MMU: Avoid calling gfn_to_page() in mmu_set_spte()
Since gfn_to_page() is a sleeping function, and we want to make the core mmu spinlocked, we need to pass the page from the walker context (which can sleep) to the shadow context (which cannot). [marcelo: avoid recursive locking of mmap_sem] Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity
Родитель
7ec5458821
Коммит
d7824fff89
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@ -890,11 +890,10 @@ struct page *gva_to_page(struct kvm_vcpu *vcpu, gva_t gva)
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static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte,
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unsigned pt_access, unsigned pte_access,
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int user_fault, int write_fault, int dirty,
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int *ptwrite, gfn_t gfn)
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int *ptwrite, gfn_t gfn, struct page *page)
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{
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u64 spte;
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int was_rmapped = is_rmap_pte(*shadow_pte);
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struct page *page;
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pgprintk("%s: spte %llx access %x write_fault %d"
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" user_fault %d gfn %lx\n",
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@ -912,8 +911,6 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte,
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if (!(pte_access & ACC_EXEC_MASK))
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spte |= PT64_NX_MASK;
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page = gfn_to_page(vcpu->kvm, gfn);
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spte |= PT_PRESENT_MASK;
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if (pte_access & ACC_USER_MASK)
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spte |= PT_USER_MASK;
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@ -979,6 +976,11 @@ static int __nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
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int level = PT32E_ROOT_LEVEL;
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hpa_t table_addr = vcpu->arch.mmu.root_hpa;
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int pt_write = 0;
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struct page *page;
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down_read(¤t->mm->mmap_sem);
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page = gfn_to_page(vcpu->kvm, gfn);
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up_read(¤t->mm->mmap_sem);
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for (; ; level--) {
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u32 index = PT64_INDEX(v, level);
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@ -989,7 +991,7 @@ static int __nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
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if (level == 1) {
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mmu_set_spte(vcpu, &table[index], ACC_ALL, ACC_ALL,
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0, write, 1, &pt_write, gfn);
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0, write, 1, &pt_write, gfn, page);
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return pt_write || is_io_pte(table[index]);
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}
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@ -1005,6 +1007,7 @@ static int __nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
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NULL);
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if (!new_table) {
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pgprintk("nonpaging_map: ENOMEM\n");
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kvm_release_page_clean(page);
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return -ENOMEM;
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}
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@ -1347,6 +1350,43 @@ static bool last_updated_pte_accessed(struct kvm_vcpu *vcpu)
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return !!(spte && (*spte & PT_ACCESSED_MASK));
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}
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static void mmu_guess_page_from_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
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const u8 *new, int bytes)
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{
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gfn_t gfn;
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int r;
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u64 gpte = 0;
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if (bytes != 4 && bytes != 8)
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return;
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/*
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* Assume that the pte write on a page table of the same type
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* as the current vcpu paging mode. This is nearly always true
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* (might be false while changing modes). Note it is verified later
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* by update_pte().
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*/
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if (is_pae(vcpu)) {
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/* Handle a 32-bit guest writing two halves of a 64-bit gpte */
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if ((bytes == 4) && (gpa % 4 == 0)) {
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r = kvm_read_guest(vcpu->kvm, gpa & ~(u64)7, &gpte, 8);
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if (r)
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return;
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memcpy((void *)&gpte + (gpa % 8), new, 4);
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} else if ((bytes == 8) && (gpa % 8 == 0)) {
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memcpy((void *)&gpte, new, 8);
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}
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} else {
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if ((bytes == 4) && (gpa % 4 == 0))
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memcpy((void *)&gpte, new, 4);
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}
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if (!is_present_pte(gpte))
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return;
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gfn = (gpte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
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vcpu->arch.update_pte.gfn = gfn;
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vcpu->arch.update_pte.page = gfn_to_page(vcpu->kvm, gfn);
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}
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void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
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const u8 *new, int bytes)
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{
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@ -1367,6 +1407,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
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int npte;
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pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes);
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mmu_guess_page_from_pte_write(vcpu, gpa, new, bytes);
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mutex_lock(&vcpu->kvm->lock);
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++vcpu->kvm->stat.mmu_pte_write;
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kvm_mmu_audit(vcpu, "pre pte write");
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@ -1437,6 +1478,10 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
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}
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kvm_mmu_audit(vcpu, "post pte write");
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mutex_unlock(&vcpu->kvm->lock);
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if (vcpu->arch.update_pte.page) {
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kvm_release_page_clean(vcpu->arch.update_pte.page);
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vcpu->arch.update_pte.page = NULL;
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}
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}
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int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
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@ -245,6 +245,7 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
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{
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pt_element_t gpte;
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unsigned pte_access;
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struct page *npage;
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gpte = *(const pt_element_t *)pte;
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if (~gpte & (PT_PRESENT_MASK | PT_ACCESSED_MASK)) {
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@ -256,8 +257,14 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
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return;
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pgprintk("%s: gpte %llx spte %p\n", __FUNCTION__, (u64)gpte, spte);
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pte_access = page->role.access & FNAME(gpte_access)(vcpu, gpte);
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if (gpte_to_gfn(gpte) != vcpu->arch.update_pte.gfn)
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return;
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npage = vcpu->arch.update_pte.page;
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if (!npage)
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return;
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get_page(npage);
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mmu_set_spte(vcpu, spte, page->role.access, pte_access, 0, 0,
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gpte & PT_DIRTY_MASK, NULL, gpte_to_gfn(gpte));
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gpte & PT_DIRTY_MASK, NULL, gpte_to_gfn(gpte), npage);
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}
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/*
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@ -265,7 +272,8 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
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*/
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static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
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struct guest_walker *walker,
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int user_fault, int write_fault, int *ptwrite)
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int user_fault, int write_fault, int *ptwrite,
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struct page *page)
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{
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hpa_t shadow_addr;
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int level;
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@ -321,8 +329,10 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
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r = kvm_read_guest_atomic(vcpu->kvm,
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walker->pte_gpa[level - 2],
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&curr_pte, sizeof(curr_pte));
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if (r || curr_pte != walker->ptes[level - 2])
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if (r || curr_pte != walker->ptes[level - 2]) {
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kvm_release_page_clean(page);
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return NULL;
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}
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}
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shadow_addr = __pa(shadow_page->spt);
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shadow_pte = shadow_addr | PT_PRESENT_MASK | PT_ACCESSED_MASK
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@ -333,7 +343,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
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mmu_set_spte(vcpu, shadow_ent, access, walker->pte_access & access,
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user_fault, write_fault,
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walker->ptes[walker->level-1] & PT_DIRTY_MASK,
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ptwrite, walker->gfn);
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ptwrite, walker->gfn, page);
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return shadow_ent;
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}
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@ -362,6 +372,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
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u64 *shadow_pte;
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int write_pt = 0;
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int r;
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struct page *page;
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pgprintk("%s: addr %lx err %x\n", __FUNCTION__, addr, error_code);
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kvm_mmu_audit(vcpu, "pre page fault");
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@ -388,9 +399,11 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
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return 0;
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}
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page = gfn_to_page(vcpu->kvm, walker.gfn);
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mutex_lock(&vcpu->kvm->lock);
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shadow_pte = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
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&write_pt);
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&write_pt, page);
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pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __FUNCTION__,
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shadow_pte, *shadow_pte, write_pt);
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@ -224,6 +224,11 @@ struct kvm_vcpu_arch {
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int last_pt_write_count;
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u64 *last_pte_updated;
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struct {
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gfn_t gfn; /* presumed gfn during guest pte update */
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struct page *page; /* page corresponding to that gfn */
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} update_pte;
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struct i387_fxsave_struct host_fx_image;
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struct i387_fxsave_struct guest_fx_image;
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