virt: acrn: Introduce PCI configuration space PIO accesses combiner

A User VM can access its virtual PCI configuration spaces via port IO
approach, which has two following steps:
 1) writes address into port 0xCF8
 2) put/get data in/from port 0xCFC

To distribute a complete PCI configuration space access one time, HSM
need to combine such two accesses together.

Combine two paired PIO I/O requests into one PCI I/O request and
continue the I/O request distribution.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Link: https://lore.kernel.org/r/20210207031040.49576-11-shuo.a.liu@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/virt/acrn/acrn_drv.h

@@ -154,6 +154,7 @@ extern rwlock_t acrn_vm_list_lock;
  * @default_client:		The default I/O request client
  * @ioreq_buf:			I/O request shared buffer
  * @ioreq_page:			The page of the I/O request shared buffer
+ * @pci_conf_addr:		Address of a PCI configuration access emulation
  */
 struct acrn_vm {
 	struct list_head		list;
@@ -168,6 +169,7 @@ struct acrn_vm {
 	struct acrn_ioreq_client	*default_client;
 	struct acrn_io_request_buffer	*ioreq_buf;
 	struct page			*ioreq_page;
+	u32				pci_conf_addr;
 };
 
 struct acrn_vm *acrn_vm_create(struct acrn_vm *vm,

drivers/virt/acrn/ioreq.c

@@ -222,6 +222,80 @@ int acrn_ioreq_client_wait(struct acrn_ioreq_client *client)
 	return 0;
 }
 
+static bool is_cfg_addr(struct acrn_io_request *req)
+{
+	return ((req->type == ACRN_IOREQ_TYPE_PORTIO) &&
+		(req->reqs.pio_request.address == 0xcf8));
+}
+
+static bool is_cfg_data(struct acrn_io_request *req)
+{
+	return ((req->type == ACRN_IOREQ_TYPE_PORTIO) &&
+		((req->reqs.pio_request.address >= 0xcfc) &&
+		 (req->reqs.pio_request.address < (0xcfc + 4))));
+}
+
+/* The low 8-bit of supported pci_reg addr.*/
+#define PCI_LOWREG_MASK  0xFC
+/* The high 4-bit of supported pci_reg addr */
+#define PCI_HIGHREG_MASK 0xF00
+/* Max number of supported functions */
+#define PCI_FUNCMAX	7
+/* Max number of supported slots */
+#define PCI_SLOTMAX	31
+/* Max number of supported buses */
+#define PCI_BUSMAX	255
+#define CONF1_ENABLE	0x80000000UL
+/*
+ * A PCI configuration space access via PIO 0xCF8 and 0xCFC normally has two
+ * following steps:
+ *   1) writes address into 0xCF8 port
+ *   2) accesses data in/from 0xCFC
+ * This function combines such paired PCI configuration space I/O requests into
+ * one ACRN_IOREQ_TYPE_PCICFG type I/O request and continues the processing.
+ */
+static bool handle_cf8cfc(struct acrn_vm *vm,
+			  struct acrn_io_request *req, u16 vcpu)
+{
+	int offset, pci_cfg_addr, pci_reg;
+	bool is_handled = false;
+
+	if (is_cfg_addr(req)) {
+		WARN_ON(req->reqs.pio_request.size != 4);
+		if (req->reqs.pio_request.direction == ACRN_IOREQ_DIR_WRITE)
+			vm->pci_conf_addr = req->reqs.pio_request.value;
+		else
+			req->reqs.pio_request.value = vm->pci_conf_addr;
+		is_handled = true;
+	} else if (is_cfg_data(req)) {
+		if (!(vm->pci_conf_addr & CONF1_ENABLE)) {
+			if (req->reqs.pio_request.direction ==
+					ACRN_IOREQ_DIR_READ)
+				req->reqs.pio_request.value = 0xffffffff;
+			is_handled = true;
+		} else {
+			offset = req->reqs.pio_request.address - 0xcfc;
+
+			req->type = ACRN_IOREQ_TYPE_PCICFG;
+			pci_cfg_addr = vm->pci_conf_addr;
+			req->reqs.pci_request.bus =
+					(pci_cfg_addr >> 16) & PCI_BUSMAX;
+			req->reqs.pci_request.dev =
+					(pci_cfg_addr >> 11) & PCI_SLOTMAX;
+			req->reqs.pci_request.func =
+					(pci_cfg_addr >> 8) & PCI_FUNCMAX;
+			pci_reg = (pci_cfg_addr & PCI_LOWREG_MASK) +
+				   ((pci_cfg_addr >> 16) & PCI_HIGHREG_MASK);
+			req->reqs.pci_request.reg = pci_reg + offset;
+		}
+	}
+
+	if (is_handled)
+		ioreq_complete_request(vm, vcpu, req);
+
+	return is_handled;
+}
+
 static bool in_range(struct acrn_ioreq_range *range,
 		     struct acrn_io_request *req)
 {
@@ -382,6 +456,8 @@ static int acrn_ioreq_dispatch(struct acrn_vm *vm)
 				ioreq_complete_request(vm, i, req);
 				continue;
 			}
+			if (handle_cf8cfc(vm, req, i))
+				continue;
 
 			spin_lock_bh(&vm->ioreq_clients_lock);
 			client = find_ioreq_client(vm, req);

include/uapi/linux/acrn.h

@@ -23,6 +23,7 @@
 
 #define ACRN_IOREQ_TYPE_PORTIO		0
 #define ACRN_IOREQ_TYPE_MMIO		1
+#define ACRN_IOREQ_TYPE_PCICFG		2
 
 #define ACRN_IOREQ_DIR_READ		0
 #define ACRN_IOREQ_DIR_WRITE		1
@@ -59,6 +60,30 @@ struct acrn_pio_request {
 	__u32	value;
 };
 
+/**
+ * struct acrn_pci_request - Info of a PCI I/O request
+ * @direction:	Access direction of this request (ACRN_IOREQ_DIR_*)
+ * @reserved:	Reserved for alignment and should be 0
+ * @size:	Access size of this PCI I/O request
+ * @value:	Read/write value of this PIO I/O request
+ * @bus:	PCI bus value of this PCI I/O request
+ * @dev:	PCI device value of this PCI I/O request
+ * @func:	PCI function value of this PCI I/O request
+ * @reg:	PCI config space offset of this PCI I/O request
+ *
+ * Need keep same header layout with &struct acrn_pio_request.
+ */
+struct acrn_pci_request {
+	__u32	direction;
+	__u32	reserved[3];
+	__u64	size;
+	__u32	value;
+	__u32	bus;
+	__u32	dev;
+	__u32	func;
+	__u32	reg;
+};
+
 /**
  * struct acrn_io_request - 256-byte ACRN I/O request
  * @type:		Type of this request (ACRN_IOREQ_TYPE_*).
@@ -67,6 +92,7 @@ struct acrn_pio_request {
  * @reserved0:		Reserved fields.
  * @reqs:		Union of different types of request. Byte offset: 64.
  * @reqs.pio_request:	PIO request data of the I/O request.
+ * @reqs.pci_request:	PCI configuration space request data of the I/O request.
  * @reqs.mmio_request:	MMIO request data of the I/O request.
  * @reqs.data:		Raw data of the I/O request.
  * @reserved1:		Reserved fields.
@@ -126,6 +152,7 @@ struct acrn_io_request {
 	__u32	reserved0[14];
 	union {
 		struct acrn_pio_request		pio_request;
+		struct acrn_pci_request		pci_request;
 		struct acrn_mmio_request	mmio_request;
 		__u64				data[8];
 	} reqs;