Re: [PATCH] Support for in-kernel mmio handlers

["Gregory Haskins" <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>]

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The attachment contains fixes based on the feedback from Chris.

Thanks Chris!

Regards,
-Greg 


[-- Attachment #2: mmio.patch --]
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diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index fceeb84..0e6eb04 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -236,6 +236,54 @@ struct kvm_pio_request {
 	int rep;
 };
 
+struct kvm_io_device {
+	unsigned long (*read)(struct kvm_io_device *this,
+			      gpa_t addr,
+			      unsigned long length);
+	void (*write)(struct kvm_io_device *this,
+		      gpa_t addr,
+		      unsigned long length,
+		      unsigned long val);
+	int (*in_range)(struct kvm_io_device *this, gpa_t addr);
+
+	void             *private;
+	struct list_head  link;
+};
+
+/* It would be nice to use something smarter than a linear search, TBD...
+ * Thankfully we dont expect many devices to register (famous last words :),
+ * so until then it will suffice.  At least its abstracted so we can change
+ * in one place.
+ */
+struct kvm_io_bus {
+	struct list_head list;
+};
+
+static inline void 
+kvm_io_bus_init(struct kvm_io_bus *bus)
+{
+	INIT_LIST_HEAD(&bus->list);
+}
+
+static inline struct kvm_io_device* 
+kvm_io_bus_find_dev(struct kvm_io_bus *bus, gpa_t addr)
+{
+	struct kvm_io_device *pos = NULL;
+
+	list_for_each_entry(pos, &bus->list, link) {
+		if (pos->in_range(pos, addr))
+			return pos;
+	}
+
+	return NULL;
+}
+
+static inline void 
+kvm_io_bus_register_dev(struct kvm_io_bus *bus, struct kvm_io_device *dev)
+{
+	list_add_tail(&dev->link, &bus->list);
+}
+
 struct kvm_vcpu {
 	struct kvm *kvm;
 	union {
@@ -294,6 +342,7 @@ struct kvm_vcpu {
 	gpa_t mmio_phys_addr;
 	struct kvm_pio_request pio;
 	void *pio_data;
+	struct kvm_io_bus mmio_bus;
 
 	int sigset_active;
 	sigset_t sigset;
@@ -345,6 +394,7 @@ struct kvm {
 	unsigned long rmap_overflow;
 	struct list_head vm_list;
 	struct file *filp;
+	struct kvm_io_bus mmio_bus;
 };
 
 struct kvm_stat {
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 4473174..c8109b7 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -294,6 +294,7 @@ static struct kvm *kvm_create_vm(void)
 
 	spin_lock_init(&kvm->lock);
 	INIT_LIST_HEAD(&kvm->active_mmu_pages);
+	kvm_io_bus_init(&kvm->mmio_bus);
 	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
 		struct kvm_vcpu *vcpu = &kvm->vcpus[i];
 
@@ -302,6 +303,7 @@ static struct kvm *kvm_create_vm(void)
 		vcpu->kvm = kvm;
 		vcpu->mmu.root_hpa = INVALID_PAGE;
 		INIT_LIST_HEAD(&vcpu->free_pages);
+		kvm_io_bus_init(&vcpu->mmio_bus);
 		spin_lock(&kvm_lock);
 		list_add(&kvm->vm_list, &vm_list);
 		spin_unlock(&kvm_lock);
@@ -1015,12 +1017,30 @@ static int emulator_write_std(unsigned long addr,
 	return X86EMUL_UNHANDLEABLE;
 }
 
+static struct kvm_io_device* vcpu_find_mmio_dev(struct kvm_vcpu *vcpu, 
+						gpa_t addr)
+{
+	struct kvm_io_device *mmio_dev;
+
+	/* First check the local CPU addresses */
+	mmio_dev = kvm_io_bus_find_dev(&vcpu->mmio_bus, addr);
+	if (!mmio_dev) {
+		/* Then check the entire VM */
+		mmio_dev = kvm_io_bus_find_dev(&vcpu->kvm->mmio_bus, addr);
+	}
+	
+	return mmio_dev;
+}
+
 static int emulator_read_emulated(unsigned long addr,
 				  unsigned long *val,
 				  unsigned int bytes,
 				  struct x86_emulate_ctxt *ctxt)
 {
 	struct kvm_vcpu *vcpu = ctxt->vcpu;
+	gpa_t gpa;
+	int i;
+	struct kvm_io_device *mmio_dev;
 
 	if (vcpu->mmio_read_completed) {
 		memcpy(val, vcpu->mmio_data, bytes);
@@ -1029,18 +1049,24 @@ static int emulator_read_emulated(unsigned long addr,
 	} else if (emulator_read_std(addr, val, bytes, ctxt)
 		   == X86EMUL_CONTINUE)
 		return X86EMUL_CONTINUE;
-	else {
-		gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
 
-		if (gpa == UNMAPPED_GVA)
-			return X86EMUL_PROPAGATE_FAULT;
-		vcpu->mmio_needed = 1;
-		vcpu->mmio_phys_addr = gpa;
-		vcpu->mmio_size = bytes;
-		vcpu->mmio_is_write = 0;
+	gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
+	if (gpa == UNMAPPED_GVA)
+		return vcpu_printf(vcpu, "not present\n"), X86EMUL_PROPAGATE_FAULT;
 
-		return X86EMUL_UNHANDLEABLE;
+	/* Is this MMIO handled locally? */
+	mmio_dev = vcpu_find_mmio_dev(vcpu, gpa);
+	if (mmio_dev) {
+		*val = mmio_dev->read(mmio_dev, gpa, bytes);
+		return X86EMUL_CONTINUE;
 	}
+
+	vcpu->mmio_needed = 1;
+	vcpu->mmio_phys_addr = gpa;
+	vcpu->mmio_size = bytes;
+	vcpu->mmio_is_write = 0;
+	
+	return X86EMUL_UNHANDLEABLE;
 }
 
 static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
@@ -1070,6 +1096,8 @@ static int emulator_write_emulated(unsigned long addr,
 {
 	struct kvm_vcpu *vcpu = ctxt->vcpu;
 	gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
+	int i;
+	struct kvm_io_device *mmio_dev;
 
 	if (gpa == UNMAPPED_GVA)
 		return X86EMUL_PROPAGATE_FAULT;
@@ -1077,6 +1105,13 @@ static int emulator_write_emulated(unsigned long addr,
 	if (emulator_write_phys(vcpu, gpa, val, bytes))
 		return X86EMUL_CONTINUE;
 
+	/* Is this MMIO handled locally? */
+	mmio_dev = vcpu_find_mmio_dev(vcpu, gpa);
+	if (mmio_dev) {
+		mmio_dev->write(mmio_dev, gpa, bytes, val);
+		return X86EMUL_CONTINUE;
+	}
+
 	vcpu->mmio_needed = 1;
 	vcpu->mmio_phys_addr = gpa;
 	vcpu->mmio_size = bytes;

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