[PATCH RFC v2 07/18] dmaengine: idxd: add DEV-MSI support in base driver

[Dave Jiang <dave.jiang@intel.com>]

In preparation for support of VFIO mediated device for idxd driver, the
enabling for Interrupt Message Store (IMS) interrupts is added for the idxd
base driver. DEV-MSI is the generic kernel support that mechanisms like
IMS can use to get their interrupts enabled. With IMS support the idxd
driver can dynamically allocate interrupts on a per mdev basis based on how
many IMS vectors that are mapped to the mdev device. This commit only
provides the support functions in the base driver and not the VFIO mdev
code utilization.

The commit has some portal related changes. A "portal" is a special
location within the MMIO BAR2 of the DSA device where descriptors are
submitted via the CPU command MOVDIR64B or ENQCMD(S). The offset for the
portal address determines whether the submitted descriptor is for MSI-X
or IMS notification.

See Intel SIOV spec for more details:
https://software.intel.com/en-us/download/intel-scalable-io-virtualization-technical-specification

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
---
 drivers/dma/idxd/Makefile |    2 +-
 drivers/dma/idxd/cdev.c   |    4 ++-
 drivers/dma/idxd/idxd.h   |   14 ++++++++----
 drivers/dma/idxd/ims.c    |   53 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/dma/idxd/init.c   |   52 ++++++++++++++++++++++++++++++++++++++++++++
 drivers/dma/idxd/submit.c |   10 +++++++-
 drivers/dma/idxd/sysfs.c  |   11 +++++++++
 7 files changed, 137 insertions(+), 9 deletions(-)
 create mode 100644 drivers/dma/idxd/ims.c

diff --git a/drivers/dma/idxd/Makefile b/drivers/dma/idxd/Makefile
index 8978b898d777..d1519b9d1dd0 100644
--- a/drivers/dma/idxd/Makefile
+++ b/drivers/dma/idxd/Makefile
@@ -1,2 +1,2 @@
 obj-$(CONFIG_INTEL_IDXD) += idxd.o
-idxd-y := init.o irq.o device.o sysfs.o submit.o dma.o cdev.o
+idxd-y := init.o irq.o device.o sysfs.o submit.o dma.o cdev.o ims.o
diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
index d4841d8c0928..ffeae646f947 100644
--- a/drivers/dma/idxd/cdev.c
+++ b/drivers/dma/idxd/cdev.c
@@ -202,8 +202,8 @@ static int idxd_cdev_mmap(struct file *filp, struct vm_area_struct *vma)
 		return rc;
 
 	vma->vm_flags |= VM_DONTCOPY;
-	pfn = (base + idxd_get_wq_portal_full_offset(wq->id,
-				IDXD_PORTAL_LIMITED)) >> PAGE_SHIFT;
+	pfn = (base + idxd_get_wq_portal_full_offset(wq->id, IDXD_PORTAL_LIMITED,
+						     IDXD_IRQ_MSIX)) >> PAGE_SHIFT;
 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 	vma->vm_private_data = ctx;
 
diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
index 2cd190a3da73..c65fb6dcb7e0 100644
--- a/drivers/dma/idxd/idxd.h
+++ b/drivers/dma/idxd/idxd.h
@@ -152,6 +152,7 @@ enum idxd_device_flag {
 	IDXD_FLAG_CONFIGURABLE = 0,
 	IDXD_FLAG_CMD_RUNNING,
 	IDXD_FLAG_PASID_ENABLED,
+	IDXD_FLAG_SIOV_SUPPORTED,
 };
 
 struct idxd_device {
@@ -178,6 +179,7 @@ struct idxd_device {
 
 	int num_groups;
 
+	u32 ims_offset;
 	u32 msix_perm_offset;
 	u32 wqcfg_offset;
 	u32 grpcfg_offset;
@@ -185,6 +187,7 @@ struct idxd_device {
 
 	u64 max_xfer_bytes;
 	u32 max_batch_size;
+	int ims_size;
 	int max_groups;
 	int max_engines;
 	int max_tokens;
@@ -204,6 +207,7 @@ struct idxd_device {
 	struct work_struct work;
 
 	int *int_handles;
+	struct sbitmap ims_sbmap;
 };
 
 /* IDXD software descriptor */
@@ -251,15 +255,17 @@ enum idxd_interrupt_type {
 	IDXD_IRQ_IMS,
 };
 
-static inline int idxd_get_wq_portal_offset(enum idxd_portal_prot prot)
+static inline int idxd_get_wq_portal_offset(enum idxd_portal_prot prot,
+					    enum idxd_interrupt_type irq_type)
 {
-	return prot * 0x1000;
+	return prot * 0x1000 + irq_type * 0x2000;
 }
 
 static inline int idxd_get_wq_portal_full_offset(int wq_id,
-						 enum idxd_portal_prot prot)
+						 enum idxd_portal_prot prot,
+						 enum idxd_interrupt_type irq_type)
 {
-	return ((wq_id * 4) << PAGE_SHIFT) + idxd_get_wq_portal_offset(prot);
+	return ((wq_id * 4) << PAGE_SHIFT) + idxd_get_wq_portal_offset(prot, irq_type);
 }
 
 static inline void idxd_set_type(struct idxd_device *idxd)
diff --git a/drivers/dma/idxd/ims.c b/drivers/dma/idxd/ims.c
new file mode 100644
index 000000000000..5fece66122a2
--- /dev/null
+++ b/drivers/dma/idxd/ims.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2019,2020 Intel Corporation. All rights rsvd. */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/device.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/msi.h>
+#include <uapi/linux/idxd.h>
+#include "registers.h"
+#include "idxd.h"
+
+static void idxd_free_ims_index(struct idxd_device *idxd,
+				unsigned long ims_idx)
+{
+	sbitmap_clear_bit(&idxd->ims_sbmap, ims_idx);
+}
+
+static int idxd_alloc_ims_index(struct idxd_device *idxd)
+{
+	int index;
+
+	index = sbitmap_get(&idxd->ims_sbmap, 0, false);
+	if (index < 0)
+		return -ENOSPC;
+	return index;
+}
+
+static unsigned int idxd_ims_irq_mask(struct msi_desc *desc)
+{
+	// Filled out later when VDCM is introduced.
+
+	return 0;
+}
+
+static unsigned int idxd_ims_irq_unmask(struct msi_desc *desc)
+{
+	// Filled out later when VDCM is introduced.
+
+	return 0;
+}
+
+static void idxd_ims_write_msg(struct msi_desc *desc, struct msi_msg *msg)
+{
+	// Filled out later when VDCM is introduced.
+}
+
+static struct platform_msi_ops idxd_ims_ops  = {
+	.irq_mask		= idxd_ims_irq_mask,
+	.irq_unmask		= idxd_ims_irq_unmask,
+	.write_msg		= idxd_ims_write_msg,
+};
diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
index 9fd505a03444..3e2c7ac83daf 100644
--- a/drivers/dma/idxd/init.c
+++ b/drivers/dma/idxd/init.c
@@ -241,10 +241,51 @@ static void idxd_read_table_offsets(struct idxd_device *idxd)
 	idxd->msix_perm_offset = offsets.msix_perm * 0x100;
 	dev_dbg(dev, "IDXD MSIX Permission Offset: %#x\n",
 		idxd->msix_perm_offset);
+	idxd->ims_offset = offsets.ims * 0x100;
+	dev_dbg(dev, "IDXD IMS Offset: %#x\n", idxd->ims_offset);
 	idxd->perfmon_offset = offsets.perfmon * 0x100;
 	dev_dbg(dev, "IDXD Perfmon Offset: %#x\n", idxd->perfmon_offset);
 }
 
+#define PCI_DEVSEC_CAP		0x23
+#define SIOVDVSEC1(offset)	((offset) + 0x4)
+#define SIOVDVSEC2(offset)	((offset) + 0x8)
+#define DVSECID			0x5
+#define SIOVCAP(offset)		((offset) + 0x14)
+
+static void idxd_check_siov(struct idxd_device *idxd)
+{
+	struct pci_dev *pdev = idxd->pdev;
+	struct device *dev = &pdev->dev;
+	int dvsec;
+	u16 val16;
+	u32 val32;
+
+	dvsec = pci_find_ext_capability(pdev, PCI_DEVSEC_CAP);
+	pci_read_config_word(pdev, SIOVDVSEC1(dvsec), &val16);
+	if (val16 != PCI_VENDOR_ID_INTEL) {
+		dev_dbg(&pdev->dev, "DVSEC vendor id is not Intel\n");
+		return;
+	}
+
+	pci_read_config_word(pdev, SIOVDVSEC2(dvsec), &val16);
+	if (val16 != DVSECID) {
+		dev_dbg(&pdev->dev, "DVSEC ID is not SIOV\n");
+		return;
+	}
+
+	pci_read_config_dword(pdev, SIOVCAP(dvsec), &val32);
+	if ((val32 & 0x1) && idxd->hw.gen_cap.max_ims_mult) {
+		idxd->ims_size = idxd->hw.gen_cap.max_ims_mult * 256ULL;
+		dev_dbg(dev, "IMS size: %u\n", idxd->ims_size);
+		set_bit(IDXD_FLAG_SIOV_SUPPORTED, &idxd->flags);
+		dev_dbg(&pdev->dev, "IMS supported for device\n");
+		return;
+	}
+
+	dev_dbg(&pdev->dev, "SIOV unsupported for device\n");
+}
+
 static void idxd_read_caps(struct idxd_device *idxd)
 {
 	struct device *dev = &idxd->pdev->dev;
@@ -263,6 +304,7 @@ static void idxd_read_caps(struct idxd_device *idxd)
 	dev_dbg(dev, "max xfer size: %llu bytes\n", idxd->max_xfer_bytes);
 	idxd->max_batch_size = 1U << idxd->hw.gen_cap.max_batch_shift;
 	dev_dbg(dev, "max batch size: %u\n", idxd->max_batch_size);
+	idxd_check_siov(idxd);
 	if (idxd->hw.gen_cap.config_en)
 		set_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags);
 
@@ -397,9 +439,19 @@ static int idxd_probe(struct idxd_device *idxd)
 
 	idxd->major = idxd_cdev_get_major(idxd);
 
+	if (idxd->ims_size) {
+		rc = sbitmap_init_node(&idxd->ims_sbmap, idxd->ims_size, -1,
+				       GFP_KERNEL, dev_to_node(dev));
+		if (rc < 0)
+			goto sbitmap_fail;
+	}
 	dev_dbg(dev, "IDXD device %d probed successfully\n", idxd->id);
 	return 0;
 
+ sbitmap_fail:
+	mutex_lock(&idxd_idr_lock);
+	idr_remove(&idxd_idrs[idxd->type], idxd->id);
+	mutex_unlock(&idxd_idr_lock);
  err_idr_fail:
 	idxd_mask_error_interrupts(idxd);
 	idxd_mask_msix_vectors(idxd);
diff --git a/drivers/dma/idxd/submit.c b/drivers/dma/idxd/submit.c
index 70c7703a4495..f0a0a0d21a7a 100644
--- a/drivers/dma/idxd/submit.c
+++ b/drivers/dma/idxd/submit.c
@@ -30,7 +30,13 @@ static struct idxd_desc *__get_desc(struct idxd_wq *wq, int idx, int cpu)
 		desc->hw->int_handle = wq->vec_ptr;
 	} else {
 		desc->vec_ptr = wq->vec_ptr;
-		desc->hw->int_handle = idxd->int_handles[desc->vec_ptr];
+		/*
+		 * int_handles are only for descriptor completion. However for device
+		 * MSIX enumeration, vec 0 is used for misc interrupts. Therefore even
+		 * though we are rotating through 1...N for descriptor interrupts, we
+		 * need to acqurie the int_handles from 0..N-1.
+		 */
+		desc->hw->int_handle = idxd->int_handles[desc->vec_ptr - 1];
 	}
 
 	return desc;
@@ -90,7 +96,7 @@ int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc)
 	if (idxd->state != IDXD_DEV_ENABLED)
 		return -EIO;
 
-	portal = wq->portal + idxd_get_wq_portal_offset(IDXD_PORTAL_LIMITED);
+	portal = wq->portal + idxd_get_wq_portal_offset(IDXD_PORTAL_LIMITED, IDXD_IRQ_MSIX);
 
 	/*
 	 * The wmb() flushes writes to coherent DMA data before
diff --git a/drivers/dma/idxd/sysfs.c b/drivers/dma/idxd/sysfs.c
index fa1abdf503c2..501a1d489ce3 100644
--- a/drivers/dma/idxd/sysfs.c
+++ b/drivers/dma/idxd/sysfs.c
@@ -1269,6 +1269,16 @@ static ssize_t numa_node_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(numa_node);
 
+static ssize_t ims_size_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct idxd_device *idxd =
+		container_of(dev, struct idxd_device, conf_dev);
+
+	return sprintf(buf, "%u\n", idxd->ims_size);
+}
+static DEVICE_ATTR_RO(ims_size);
+
 static ssize_t max_batch_size_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
@@ -1455,6 +1465,7 @@ static struct attribute *idxd_device_attributes[] = {
 	&dev_attr_max_work_queues_size.attr,
 	&dev_attr_max_engines.attr,
 	&dev_attr_numa_node.attr,
+	&dev_attr_ims_size.attr,
 	&dev_attr_max_batch_size.attr,
 	&dev_attr_max_transfer_size.attr,
 	&dev_attr_op_cap.attr,