From: Mihai Donțu <[email protected]> These callbacks return a boolean value. If false, the emulation should stop and the instruction should be reexecuted in guest. The preread callback can return the bytes needed by the read operation.
CC: Xiao Guangrong <[email protected]> CC: Sean Christopherson <[email protected]> Signed-off-by: Mihai Donțu <[email protected]> Signed-off-by: Adalbert Lazăr <[email protected]> --- arch/x86/include/asm/kvm_page_track.h | 19 +++- arch/x86/kvm/mmu.c | 81 +++++++++++++++++ arch/x86/kvm/mmu.h | 4 + arch/x86/kvm/page_track.c | 123 ++++++++++++++++++++++++-- 4 files changed, 217 insertions(+), 10 deletions(-) diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h index 0492a85f3a44..a431e5e1e5cb 100644 --- a/arch/x86/include/asm/kvm_page_track.h +++ b/arch/x86/include/asm/kvm_page_track.h @@ -3,7 +3,10 @@ #define _ASM_X86_KVM_PAGE_TRACK_H enum kvm_page_track_mode { + KVM_PAGE_TRACK_PREREAD, + KVM_PAGE_TRACK_PREWRITE, KVM_PAGE_TRACK_WRITE, + KVM_PAGE_TRACK_PREEXEC, KVM_PAGE_TRACK_MAX, }; @@ -22,6 +25,13 @@ struct kvm_page_track_notifier_head { struct kvm_page_track_notifier_node { struct hlist_node node; + bool (*track_preread)(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva, + u8 *new, int bytes, + struct kvm_page_track_notifier_node *node, + bool *data_ready); + bool (*track_prewrite)(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva, + const u8 *new, int bytes, + struct kvm_page_track_notifier_node *node); /* * It is called when guest is writing the write-tracked page * and write emulation is finished at that time. @@ -35,12 +45,14 @@ struct kvm_page_track_notifier_node { void (*track_write)(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva, const u8 *new, int bytes, struct kvm_page_track_notifier_node *node); + bool (*track_preexec)(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva, + struct kvm_page_track_notifier_node *node); void (*track_create_slot)(struct kvm *kvm, struct kvm_memory_slot *slot, unsigned long npages, struct kvm_page_track_notifier_node *node); /* * It is called when memory slot is being moved or removed - * users can drop write-protection for the pages in that memory slot + * users can drop active protection for the pages in that memory slot * * @kvm: the kvm where memory slot being moved or removed * @slot: the memory slot being moved or removed @@ -73,7 +85,12 @@ kvm_page_track_register_notifier(struct kvm *kvm, void kvm_page_track_unregister_notifier(struct kvm *kvm, struct kvm_page_track_notifier_node *n); +bool kvm_page_track_preread(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva, + u8 *new, int bytes, bool *data_ready); +bool kvm_page_track_prewrite(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva, + const u8 *new, int bytes); void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva, const u8 *new, int bytes); +bool kvm_page_track_preexec(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva); void kvm_page_track_flush_slot(struct kvm *kvm, struct kvm_memory_slot *slot); #endif diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 9898d863b6b6..a86b165cf6dd 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1523,6 +1523,31 @@ static bool spte_write_protect(u64 *sptep, bool pt_protect) return mmu_spte_update(sptep, spte); } +static bool spte_read_protect(u64 *sptep) +{ + u64 spte = *sptep; + bool exec_only_supported = (shadow_present_mask == 0ull); + + rmap_printk("rmap_read_protect: spte %p %llx\n", sptep, *sptep); + + WARN_ON_ONCE(!exec_only_supported); + + spte = spte & ~(PT_WRITABLE_MASK | PT_PRESENT_MASK); + + return mmu_spte_update(sptep, spte); +} + +static bool spte_exec_protect(u64 *sptep) +{ + u64 spte = *sptep; + + rmap_printk("rmap_exec_protect: spte %p %llx\n", sptep, *sptep); + + spte = spte & ~PT_USER_MASK; + + return mmu_spte_update(sptep, spte); +} + static bool __rmap_write_protect(struct kvm *kvm, struct kvm_rmap_head *rmap_head, bool pt_protect) @@ -1537,6 +1562,32 @@ static bool __rmap_write_protect(struct kvm *kvm, return flush; } +static bool __rmap_read_protect(struct kvm *kvm, + struct kvm_rmap_head *rmap_head) +{ + u64 *sptep; + struct rmap_iterator iter; + bool flush = false; + + for_each_rmap_spte(rmap_head, &iter, sptep) + flush |= spte_read_protect(sptep); + + return flush; +} + +static bool __rmap_exec_protect(struct kvm *kvm, + struct kvm_rmap_head *rmap_head) +{ + u64 *sptep; + struct rmap_iterator iter; + bool flush = false; + + for_each_rmap_spte(rmap_head, &iter, sptep) + flush |= spte_exec_protect(sptep); + + return flush; +} + static bool spte_clear_dirty(u64 *sptep) { u64 spte = *sptep; @@ -1707,6 +1758,36 @@ bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, return write_protected; } +bool kvm_mmu_slot_gfn_read_protect(struct kvm *kvm, + struct kvm_memory_slot *slot, u64 gfn) +{ + struct kvm_rmap_head *rmap_head; + int i; + bool read_protected = false; + + for (i = PT_PAGE_TABLE_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) { + rmap_head = __gfn_to_rmap(gfn, i, slot); + read_protected |= __rmap_read_protect(kvm, rmap_head); + } + + return read_protected; +} + +bool kvm_mmu_slot_gfn_exec_protect(struct kvm *kvm, + struct kvm_memory_slot *slot, u64 gfn) +{ + struct kvm_rmap_head *rmap_head; + int i; + bool exec_protected = false; + + for (i = PT_PAGE_TABLE_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) { + rmap_head = __gfn_to_rmap(gfn, i, slot); + exec_protected |= __rmap_exec_protect(kvm, rmap_head); + } + + return exec_protected; +} + static bool rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn) { struct kvm_memory_slot *slot; diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index c7b333147c4a..45948dabe0b6 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -210,5 +210,9 @@ void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn); void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn); bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, struct kvm_memory_slot *slot, u64 gfn); +bool kvm_mmu_slot_gfn_read_protect(struct kvm *kvm, + struct kvm_memory_slot *slot, u64 gfn); +bool kvm_mmu_slot_gfn_exec_protect(struct kvm *kvm, + struct kvm_memory_slot *slot, u64 gfn); int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu); #endif diff --git a/arch/x86/kvm/page_track.c b/arch/x86/kvm/page_track.c index ff7defb4a1d2..fc792939a05c 100644 --- a/arch/x86/kvm/page_track.c +++ b/arch/x86/kvm/page_track.c @@ -1,5 +1,5 @@ /* - * Support KVM gust page tracking + * Support KVM guest page tracking * * This feature allows us to track page access in guest. Currently, only * write access is tracked. @@ -101,7 +101,7 @@ static void update_gfn_track(struct kvm_memory_slot *slot, gfn_t gfn, * @kvm: the guest instance we are interested in. * @slot: the @gfn belongs to. * @gfn: the guest page. - * @mode: tracking mode, currently only write track is supported. + * @mode: tracking mode. */ void kvm_slot_page_track_add_page(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn, @@ -119,9 +119,16 @@ void kvm_slot_page_track_add_page(struct kvm *kvm, */ kvm_mmu_gfn_disallow_lpage(slot, gfn); - if (mode == KVM_PAGE_TRACK_WRITE) + if (mode == KVM_PAGE_TRACK_PREWRITE || mode == KVM_PAGE_TRACK_WRITE) { if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn)) kvm_flush_remote_tlbs(kvm); + } else if (mode == KVM_PAGE_TRACK_PREREAD) { + if (kvm_mmu_slot_gfn_read_protect(kvm, slot, gfn)) + kvm_flush_remote_tlbs(kvm); + } else if (mode == KVM_PAGE_TRACK_PREEXEC) { + if (kvm_mmu_slot_gfn_exec_protect(kvm, slot, gfn)) + kvm_flush_remote_tlbs(kvm); + } } EXPORT_SYMBOL_GPL(kvm_slot_page_track_add_page); @@ -136,7 +143,7 @@ EXPORT_SYMBOL_GPL(kvm_slot_page_track_add_page); * @kvm: the guest instance we are interested in. * @slot: the @gfn belongs to. * @gfn: the guest page. - * @mode: tracking mode, currently only write track is supported. + * @mode: tracking mode. */ void kvm_slot_page_track_remove_page(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn, @@ -229,12 +236,81 @@ kvm_page_track_unregister_notifier(struct kvm *kvm, } EXPORT_SYMBOL_GPL(kvm_page_track_unregister_notifier); +/* + * Notify the node that a read access is about to happen. Returning false + * doesn't stop the other nodes from being called, but it will stop + * the emulation. + * + * The node should figure out if the written page is the one that the node + * is interested in by itself. + * + * The nodes will always be in conflict if they track the same page: + * - accepting a read won't guarantee that the next node will not override + * the data (filling new/bytes and setting data_ready) + * - filling new/bytes with custom data won't guarantee that the next node + * will not override that + */ +bool kvm_page_track_preread(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva, + u8 *new, int bytes, bool *data_ready) +{ + struct kvm_page_track_notifier_head *head; + struct kvm_page_track_notifier_node *n; + int idx; + bool ret = true; + + *data_ready = false; + + head = &vcpu->kvm->arch.track_notifier_head; + + if (hlist_empty(&head->track_notifier_list)) + return ret; + + idx = srcu_read_lock(&head->track_srcu); + hlist_for_each_entry_rcu(n, &head->track_notifier_list, node) + if (n->track_preread) + if (!n->track_preread(vcpu, gpa, gva, new, bytes, n, + data_ready)) + ret = false; + srcu_read_unlock(&head->track_srcu, idx); + return ret; +} + +/* + * Notify the node that a write access is about to happen. Returning false + * doesn't stop the other nodes from being called, but it will stop + * the emulation. + * + * The node should figure out if the written page is the one that the node + * is interested in by itself. + */ +bool kvm_page_track_prewrite(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva, + const u8 *new, int bytes) +{ + struct kvm_page_track_notifier_head *head; + struct kvm_page_track_notifier_node *n; + int idx; + bool ret = true; + + head = &vcpu->kvm->arch.track_notifier_head; + + if (hlist_empty(&head->track_notifier_list)) + return ret; + + idx = srcu_read_lock(&head->track_srcu); + hlist_for_each_entry_rcu(n, &head->track_notifier_list, node) + if (n->track_prewrite) + if (!n->track_prewrite(vcpu, gpa, gva, new, bytes, n)) + ret = false; + srcu_read_unlock(&head->track_srcu, idx); + return ret; +} + /* * Notify the node that write access is intercepted and write emulation is * finished at this time. * - * The node should figure out if the written page is the one that node is - * interested in by itself. + * The node should figure out if the written page is the one that the node + * is interested in by itself. */ void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva, const u8 *new, int bytes) @@ -255,12 +331,41 @@ void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva, srcu_read_unlock(&head->track_srcu, idx); } +/* + * Notify the node that an instruction is about to be executed. + * Returning false doesn't stop the other nodes from being called, + * but it will stop the emulation with X86EMUL_RETRY_INSTR. + * + * The node should figure out if the written page is the one that the node + * is interested in by itself. + */ +bool kvm_page_track_preexec(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva) +{ + struct kvm_page_track_notifier_head *head; + struct kvm_page_track_notifier_node *n; + int idx; + bool ret = true; + + head = &vcpu->kvm->arch.track_notifier_head; + + if (hlist_empty(&head->track_notifier_list)) + return ret; + + idx = srcu_read_lock(&head->track_srcu); + hlist_for_each_entry_rcu(n, &head->track_notifier_list, node) + if (n->track_preexec) + if (!n->track_preexec(vcpu, gpa, gva, n)) + ret = false; + srcu_read_unlock(&head->track_srcu, idx); + return ret; +} + /* * Notify the node that memory slot is being removed or moved so that it can - * drop write-protection for the pages in the memory slot. + * drop active protection for the pages in the memory slot. * - * The node should figure out it has any write-protected pages in this slot - * by itself. + * The node should figure out if the written page is the one that the node + * is interested in by itself. */ void kvm_page_track_flush_slot(struct kvm *kvm, struct kvm_memory_slot *slot) { _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
