From: Mihai Donțu <mdontu@xxxxxxxxxxxxxxx>
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 <guangrong.xiao@xxxxxxxxx>
CC: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Mihai Donțu <mdontu@xxxxxxxxxxxxxxx>
Signed-off-by: Adalbert Lazăr <alazar@xxxxxxxxxxxxxxx>
---
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)
{
