[PATCH kvmtool v2 04/22] mmio: Extend handling to include ioport emulation

[Andre Przywara <andre.przywara@arm.com>]

In their core functionality MMIO and I/O port traps are not really
different, yet we still have two totally separate code paths for
handling them. Devices need to decide on one conduit or need to provide
different handler functions for each of them.

Extend the existing MMIO emulation to also cover ioport handlers.
This just adds another RB tree root for holding the I/O port handlers,
but otherwise uses the same tree population and lookup code.
"ioport" or "mmio" just become a flag in the registration function.
Provide wrappers to not break existing users, and allow an easy
transition for the existing ioport handlers.

This also means that ioport handlers now can use the same emulation
callback prototype as MMIO handlers, which means we have to migrate them
over. To allow a smooth transition, we hook up the new I/O emulate
function to the end of the existing ioport emulation code.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 include/kvm/kvm.h | 49 ++++++++++++++++++++++++++++++++---
 ioport.c          |  4 +--
 mmio.c            | 65 +++++++++++++++++++++++++++++++++++++++--------
 3 files changed, 102 insertions(+), 16 deletions(-)

diff --git a/include/kvm/kvm.h b/include/kvm/kvm.h
index f1f0afd7..306b258a 100644
--- a/include/kvm/kvm.h
+++ b/include/kvm/kvm.h
@@ -27,10 +27,23 @@
 #define PAGE_SIZE (sysconf(_SC_PAGE_SIZE))
 #endif
 
+/*
+ * We are reusing the existing DEVICE_BUS_MMIO and DEVICE_BUS_IOPORT constants
+ * from kvm/devices.h to differentiate between registering an I/O port and an
+ * MMIO region.
+ * To avoid collisions with future additions of more bus types, we reserve
+ * a generous 4 bits for the bus mask here.
+ */
+#define IOTRAP_BUS_MASK		0xf
+#define IOTRAP_COALESCE		(1U << 4)
+
 #define DEFINE_KVM_EXT(ext)		\
 	.name = #ext,			\
 	.code = ext
 
+struct kvm_cpu;
+typedef void (*mmio_handler_fn)(struct kvm_cpu *vcpu, u64 addr, u8 *data,
+				u32 len, u8 is_write, void *ptr);
 typedef void (*fdt_irq_fn)(void *fdt, u8 irq, enum irq_type irq_type);
 
 enum {
@@ -113,6 +126,8 @@ void kvm__irq_line(struct kvm *kvm, int irq, int level);
 void kvm__irq_trigger(struct kvm *kvm, int irq);
 bool kvm__emulate_io(struct kvm_cpu *vcpu, u16 port, void *data, int direction, int size, u32 count);
 bool kvm__emulate_mmio(struct kvm_cpu *vcpu, u64 phys_addr, u8 *data, u32 len, u8 is_write);
+bool kvm__emulate_pio(struct kvm_cpu *vcpu, u16 port, void *data,
+		      int direction, int size, u32 count);
 int kvm__destroy_mem(struct kvm *kvm, u64 guest_phys, u64 size, void *userspace_addr);
 int kvm__register_mem(struct kvm *kvm, u64 guest_phys, u64 size, void *userspace_addr,
 		      enum kvm_mem_type type);
@@ -136,10 +151,36 @@ static inline int kvm__reserve_mem(struct kvm *kvm, u64 guest_phys, u64 size)
 				 KVM_MEM_TYPE_RESERVED);
 }
 
-int __must_check kvm__register_mmio(struct kvm *kvm, u64 phys_addr, u64 phys_addr_len, bool coalesce,
-				    void (*mmio_fn)(struct kvm_cpu *vcpu, u64 addr, u8 *data, u32 len, u8 is_write, void *ptr),
-				    void *ptr);
-bool kvm__deregister_mmio(struct kvm *kvm, u64 phys_addr);
+int __must_check kvm__register_iotrap(struct kvm *kvm, u64 phys_addr, u64 len,
+				      mmio_handler_fn mmio_fn, void *ptr,
+				      unsigned int flags);
+
+static inline
+int __must_check kvm__register_mmio(struct kvm *kvm, u64 phys_addr,
+				    u64 phys_addr_len, bool coalesce,
+				    mmio_handler_fn mmio_fn, void *ptr)
+{
+	return kvm__register_iotrap(kvm, phys_addr, phys_addr_len, mmio_fn, ptr,
+			DEVICE_BUS_MMIO | (coalesce ? IOTRAP_COALESCE : 0));
+}
+static inline
+int __must_check kvm__register_pio(struct kvm *kvm, u16 port, u16 len,
+				   mmio_handler_fn mmio_fn, void *ptr)
+{
+	return kvm__register_iotrap(kvm, port, len, mmio_fn, ptr,
+				    DEVICE_BUS_IOPORT);
+}
+
+bool kvm__deregister_iotrap(struct kvm *kvm, u64 phys_addr, unsigned int flags);
+static inline bool kvm__deregister_mmio(struct kvm *kvm, u64 phys_addr)
+{
+	return kvm__deregister_iotrap(kvm, phys_addr, DEVICE_BUS_MMIO);
+}
+static inline bool kvm__deregister_pio(struct kvm *kvm, u16 port)
+{
+	return kvm__deregister_iotrap(kvm, port, DEVICE_BUS_IOPORT);
+}
+
 void kvm__reboot(struct kvm *kvm);
 void kvm__pause(struct kvm *kvm);
 void kvm__continue(struct kvm *kvm);
diff --git a/ioport.c b/ioport.c
index e0123f27..ce29e7e7 100644
--- a/ioport.c
+++ b/ioport.c
@@ -162,7 +162,8 @@ bool kvm__emulate_io(struct kvm_cpu *vcpu, u16 port, void *data, int direction,
 
 	entry = ioport_get(&ioport_tree, port);
 	if (!entry)
-		goto out;
+		return kvm__emulate_pio(vcpu, port, data, direction,
+					size, count);
 
 	ops	= entry->ops;
 
@@ -177,7 +178,6 @@ bool kvm__emulate_io(struct kvm_cpu *vcpu, u16 port, void *data, int direction,
 
 	ioport_put(&ioport_tree, entry);
 
-out:
 	if (ret)
 		return true;
 
diff --git a/mmio.c b/mmio.c
index cd141cd3..75de04ad 100644
--- a/mmio.c
+++ b/mmio.c
@@ -19,13 +19,14 @@ static DEFINE_MUTEX(mmio_lock);
 
 struct mmio_mapping {
 	struct rb_int_node	node;
-	void			(*mmio_fn)(struct kvm_cpu *vcpu, u64 addr, u8 *data, u32 len, u8 is_write, void *ptr);
+	mmio_handler_fn		mmio_fn;
 	void			*ptr;
 	u32			refcount;
 	bool			remove;
 };
 
 static struct rb_root mmio_tree = RB_ROOT;
+static struct rb_root pio_tree = RB_ROOT;
 
 static struct mmio_mapping *mmio_search(struct rb_root *root, u64 addr, u64 len)
 {
@@ -103,9 +104,14 @@ static void mmio_put(struct kvm *kvm, struct rb_root *root, struct mmio_mapping
 	mutex_unlock(&mmio_lock);
 }
 
-int kvm__register_mmio(struct kvm *kvm, u64 phys_addr, u64 phys_addr_len, bool coalesce,
-		       void (*mmio_fn)(struct kvm_cpu *vcpu, u64 addr, u8 *data, u32 len, u8 is_write, void *ptr),
-			void *ptr)
+static bool trap_is_mmio(unsigned int flags)
+{
+	return (flags & IOTRAP_BUS_MASK) == DEVICE_BUS_MMIO;
+}
+
+int kvm__register_iotrap(struct kvm *kvm, u64 phys_addr, u64 phys_addr_len,
+			 mmio_handler_fn mmio_fn, void *ptr,
+			 unsigned int flags)
 {
 	struct mmio_mapping *mmio;
 	struct kvm_coalesced_mmio_zone zone;
@@ -127,7 +133,7 @@ int kvm__register_mmio(struct kvm *kvm, u64 phys_addr, u64 phys_addr_len, bool c
 		.remove		= false,
 	};
 
-	if (coalesce) {
+	if (trap_is_mmio(flags) && (flags & IOTRAP_COALESCE)) {
 		zone = (struct kvm_coalesced_mmio_zone) {
 			.addr	= phys_addr,
 			.size	= phys_addr_len,
@@ -138,19 +144,29 @@ int kvm__register_mmio(struct kvm *kvm, u64 phys_addr, u64 phys_addr_len, bool c
 			return -errno;
 		}
 	}
+
 	mutex_lock(&mmio_lock);
-	ret = mmio_insert(&mmio_tree, mmio);
+	if (trap_is_mmio(flags))
+		ret = mmio_insert(&mmio_tree, mmio);
+	else
+		ret = mmio_insert(&pio_tree, mmio);
 	mutex_unlock(&mmio_lock);
 
 	return ret;
 }
 
-bool kvm__deregister_mmio(struct kvm *kvm, u64 phys_addr)
+bool kvm__deregister_iotrap(struct kvm *kvm, u64 phys_addr, unsigned int flags)
 {
 	struct mmio_mapping *mmio;
+	struct rb_root *tree;
+
+	if ((flags & IOTRAP_BUS_MASK) == DEVICE_BUS_IOPORT)
+		tree = &pio_tree;
+	else
+		tree = &mmio_tree;
 
 	mutex_lock(&mmio_lock);
-	mmio = mmio_search_single(&mmio_tree, phys_addr);
+	mmio = mmio_search_single(tree, phys_addr);
 	if (mmio == NULL) {
 		mutex_unlock(&mmio_lock);
 		return false;
@@ -167,7 +183,7 @@ bool kvm__deregister_mmio(struct kvm *kvm, u64 phys_addr)
 	 * called mmio_put(). This will trigger use-after-free errors on VCPU0.
 	 */
 	if (mmio->refcount == 0)
-		mmio_deregister(kvm, &mmio_tree, mmio);
+		mmio_deregister(kvm, tree, mmio);
 	else
 		mmio->remove = true;
 	mutex_unlock(&mmio_lock);
@@ -175,7 +191,8 @@ bool kvm__deregister_mmio(struct kvm *kvm, u64 phys_addr)
 	return true;
 }
 
-bool kvm__emulate_mmio(struct kvm_cpu *vcpu, u64 phys_addr, u8 *data, u32 len, u8 is_write)
+bool kvm__emulate_mmio(struct kvm_cpu *vcpu, u64 phys_addr, u8 *data,
+		       u32 len, u8 is_write)
 {
 	struct mmio_mapping *mmio;
 
@@ -194,3 +211,31 @@ bool kvm__emulate_mmio(struct kvm_cpu *vcpu, u64 phys_addr, u8 *data, u32 len, u
 out:
 	return true;
 }
+
+bool kvm__emulate_pio(struct kvm_cpu *vcpu, u16 port, void *data,
+		     int direction, int size, u32 count)
+{
+	struct mmio_mapping *mmio;
+	bool is_write = direction == KVM_EXIT_IO_OUT;
+
+	mmio = mmio_get(&pio_tree, port, size);
+	if (!mmio) {
+		if (vcpu->kvm->cfg.ioport_debug) {
+			fprintf(stderr, "IO error: %s port=%x, size=%d, count=%u\n",
+				to_direction(direction), port, size, count);
+
+			return false;
+		}
+		return true;
+	}
+
+	while (count--) {
+		mmio->mmio_fn(vcpu, port, data, size, is_write, mmio->ptr);
+
+		data += size;
+	}
+
+	mmio_put(vcpu->kvm, &pio_tree, mmio);
+
+	return true;
+}
-- 
2.17.5