linux-kernel - [RFC KVM 26/27] kvm/isolation: initialize the KVM page table with KVM memslots

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Date:   Mon, 13 May 2019 16:38:34 +0200
From:   Alexandre Chartre <alexandre.chartre@...cle.com>
To:     pbonzini@...hat.com, rkrcmar@...hat.com, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
        kvm@...r.kernel.org, x86@...nel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     konrad.wilk@...cle.com, jan.setjeeilers@...cle.com,
        liran.alon@...cle.com, jwadams@...gle.com,
        alexandre.chartre@...cle.com
Subject: [RFC KVM 26/27] kvm/isolation: initialize the KVM page table with KVM memslots

KVM memslots can change after they have been created so new memslots
have to be mapped when they are created.

TODO: we currently don't unmapped old memslots, they should be unmapped
when they are freed.

Signed-off-by: Alexandre Chartre <alexandre.chartre@...cle.com>
---
 arch/x86/kvm/isolation.c |   39 +++++++++++++++++++++++++++++++++++++++
 arch/x86/kvm/isolation.h |    1 +
 arch/x86/kvm/x86.c       |    3 +++
 3 files changed, 43 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/isolation.c b/arch/x86/kvm/isolation.c
index b0c789f..255b2da 100644
--- a/arch/x86/kvm/isolation.c
+++ b/arch/x86/kvm/isolation.c
@@ -1593,13 +1593,45 @@ static void kvm_isolation_clear_handlers(void)
 	kvm_page_fault_handler = NULL;
 }
 
+void kvm_isolation_check_memslots(struct kvm *kvm)
+{
+	struct kvm_range_mapping *rmapping;
+	int i, err;
+
+	if (!kvm_isolation())
+		return;
+
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+		rmapping = kvm_get_range_mapping(kvm->memslots[i], NULL);
+		if (rmapping)
+			continue;
+		pr_debug("remapping kvm memslots[%d]\n", i);
+		err = kvm_copy_ptes(kvm->memslots[i],
+		    sizeof(struct kvm_memslots));
+		if (err)
+			pr_debug("failed to map kvm memslots[%d]\n", i);
+	}
+
+}
+
 int kvm_isolation_init_vm(struct kvm *kvm)
 {
+	int err, i;
+
 	if (!kvm_isolation())
 		return 0;
 
 	kvm_clear_page_fault();
 
+	pr_debug("mapping kvm memslots\n");
+
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+		err = kvm_copy_ptes(kvm->memslots[i],
+		    sizeof(struct kvm_memslots));
+		if (err)
+			return err;
+	}
+
 	pr_debug("mapping kvm srcu sda\n");
 
 	return (kvm_copy_percpu_mapping(kvm->srcu.sda,
@@ -1608,9 +1640,16 @@ int kvm_isolation_init_vm(struct kvm *kvm)
 
 void kvm_isolation_destroy_vm(struct kvm *kvm)
 {
+	int i;
+
 	if (!kvm_isolation())
 		return;
 
+	pr_debug("unmapping kvm memslots\n");
+
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
+		kvm_clear_range_mapping(kvm->memslots[i]);
+
 	pr_debug("unmapping kvm srcu sda\n");
 
 	kvm_clear_percpu_mapping(kvm->srcu.sda);
diff --git a/arch/x86/kvm/isolation.h b/arch/x86/kvm/isolation.h
index 2d7d016..1e55799 100644
--- a/arch/x86/kvm/isolation.h
+++ b/arch/x86/kvm/isolation.h
@@ -32,6 +32,7 @@ static inline bool kvm_isolation(void)
 extern void kvm_clear_range_mapping(void *ptr);
 extern int kvm_copy_percpu_mapping(void *percpu_ptr, size_t size);
 extern void kvm_clear_percpu_mapping(void *percpu_ptr);
+extern void kvm_isolation_check_memslots(struct kvm *kvm);
 extern int kvm_add_task_mapping(struct task_struct *tsk);
 extern void kvm_cleanup_task_mapping(struct task_struct *tsk);
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e1cc3a6..7d98e9f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9438,6 +9438,7 @@ void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
 	 * mmio generation may have reached its maximum value.
 	 */
 	kvm_mmu_invalidate_mmio_sptes(kvm, gen);
+	kvm_isolation_check_memslots(kvm);
 }
 
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
@@ -9537,6 +9538,8 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 	 */
 	if (change != KVM_MR_DELETE)
 		kvm_mmu_slot_apply_flags(kvm, (struct kvm_memory_slot *) new);
+
+	kvm_isolation_check_memslots(kvm);
 }
 
 void kvm_arch_flush_shadow_all(struct kvm *kvm)
-- 
1.7.1