Merge tag 'pci-v4.20-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci

Pull PCI updates from Bjorn Helgaas:

 - Fix ASPM link_state teardown on removal (Lukas Wunner)

 - Fix misleading _OSC ASPM message (Sinan Kaya)

 - Make _OSC optional for PCI (Sinan Kaya)

 - Don't initialize ASPM link state when ACPI_FADT_NO_ASPM is set
   (Patrick Talbert)

 - Remove x86 and arm64 node-local allocation for host bridge structures
   (Punit Agrawal)

 - Pay attention to device-specific _PXM node values (Jonathan Cameron)

 - Support new Immediate Readiness bit (Felipe Balbi)

 - Differentiate between pciehp surprise and safe removal (Lukas Wunner)

 - Remove unnecessary pciehp includes (Lukas Wunner)

 - Drop pciehp hotplug_slot_ops wrappers (Lukas Wunner)

 - Tolerate PCIe Slot Presence Detect being hardwired to zero to
   workaround broken hardware, e.g., the Wilocity switch/wireless device
   (Lukas Wunner)

 - Unify pciehp controller & slot structs (Lukas Wunner)

 - Constify hotplug_slot_ops (Lukas Wunner)

 - Drop hotplug_slot_info (Lukas Wunner)

 - Embed hotplug_slot struct into users instead of allocating it
   separately (Lukas Wunner)

 - Initialize PCIe port service drivers directly instead of relying on
   initcall ordering (Keith Busch)

 - Restore PCI config state after a slot reset (Keith Busch)

 - Save/restore DPC config state along with other PCI config state
   (Keith Busch)

 - Reference count devices during AER handling to avoid race issue with
   concurrent hot removal (Keith Busch)

 - If an Upstream Port reports ERR_FATAL, don't try to read the Port's
   config space because it is probably unreachable (Keith Busch)

 - During error handling, use slot-specific reset instead of secondary
   bus reset to avoid link up/down issues on hotplug ports (Keith Busch)

 - Restore previous AER/DPC handling that does not remove and
   re-enumerate devices on ERR_FATAL (Keith Busch)

 - Notify all drivers that may be affected by error recovery resets
   (Keith Busch)

 - Always generate error recovery uevents, even if a driver doesn't have
   error callbacks (Keith Busch)

 - Make PCIe link active reporting detection generic (Keith Busch)

 - Support D3cold in PCIe hierarchies during system sleep and runtime,
   including hotplug and Thunderbolt ports (Mika Westerberg)

 - Handle hpmemsize/hpiosize kernel parameters uniformly, whether slots
   are empty or occupied (Jon Derrick)

 - Remove duplicated include from pci/pcie/err.c and unused variable
   from cpqphp (YueHaibing)

 - Remove driver pci_cleanup_aer_uncorrect_error_status() calls (Oza
   Pawandeep)

 - Uninline PCI bus accessors for better ftracing (Keith Busch)

 - Remove unused AER Root Port .error_resume method (Keith Busch)

 - Use kfifo in AER instead of a local version (Keith Busch)

 - Use threaded IRQ in AER bottom half (Keith Busch)

 - Use managed resources in AER core (Keith Busch)

 - Reuse pcie_port_find_device() for AER injection (Keith Busch)

 - Abstract AER interrupt handling to disconnect error injection (Keith
   Busch)

 - Refactor AER injection callbacks to simplify future improvments
   (Keith Busch)

 - Remove unused Netronome NFP32xx Device IDs (Jakub Kicinski)

 - Use bitmap_zalloc() for dma_alias_mask (Andy Shevchenko)

 - Add switch fall-through annotations (Gustavo A. R. Silva)

 - Remove unused Switchtec quirk variable (Joshua Abraham)

 - Fix pci.c kernel-doc warning (Randy Dunlap)

 - Remove trivial PCI wrappers for DMA APIs (Christoph Hellwig)

 - Add Intel GPU device IDs to spurious interrupt quirk (Bin Meng)

 - Run Switchtec DMA aliasing quirk only on NTB endpoints to avoid
   useless dmesg errors (Logan Gunthorpe)

 - Update Switchtec NTB documentation (Wesley Yung)

 - Remove redundant "default n" from Kconfig (Bartlomiej Zolnierkiewicz)

 - Avoid panic when drivers enable MSI/MSI-X twice (Tonghao Zhang)

 - Add PCI support for peer-to-peer DMA (Logan Gunthorpe)

 - Add sysfs group for PCI peer-to-peer memory statistics (Logan
   Gunthorpe)

 - Add PCI peer-to-peer DMA scatterlist mapping interface (Logan
   Gunthorpe)

 - Add PCI configfs/sysfs helpers for use by peer-to-peer users (Logan
   Gunthorpe)

 - Add PCI peer-to-peer DMA driver writer's documentation (Logan
   Gunthorpe)

 - Add block layer flag to indicate driver support for PCI peer-to-peer
   DMA (Logan Gunthorpe)

 - Map Infiniband scatterlists for peer-to-peer DMA if they contain P2P
   memory (Logan Gunthorpe)

 - Register nvme-pci CMB buffer as PCI peer-to-peer memory (Logan
   Gunthorpe)

 - Add nvme-pci support for PCI peer-to-peer memory in requests (Logan
   Gunthorpe)

 - Use PCI peer-to-peer memory in nvme (Stephen Bates, Steve Wise,
   Christoph Hellwig, Logan Gunthorpe)

 - Cache VF config space size to optimize enumeration of many VFs
   (KarimAllah Ahmed)

 - Remove unnecessary <linux/pci-ats.h> include (Bjorn Helgaas)

 - Fix VMD AERSID quirk Device ID matching (Jon Derrick)

 - Fix Cadence PHY handling during probe (Alan Douglas)

 - Signal Cadence Endpoint interrupts via AXI region 0 instead of last
   region (Alan Douglas)

 - Write Cadence Endpoint MSI interrupts with 32 bits of data (Alan
   Douglas)

 - Remove redundant controller tests for "device_type == pci" (Rob
   Herring)

 - Document R-Car E3 (R8A77990) bindings (Tho Vu)

 - Add device tree support for R-Car r8a7744 (Biju Das)

 - Drop unused mvebu PCIe capability code (Thomas Petazzoni)

 - Add shared PCI bridge emulation code (Thomas Petazzoni)

 - Convert mvebu to use shared PCI bridge emulation (Thomas Petazzoni)

 - Add aardvark Root Port emulation (Thomas Petazzoni)

 - Support 100MHz/200MHz refclocks for i.MX6 (Lucas Stach)

 - Add initial power management for i.MX7 (Leonard Crestez)

 - Add PME_Turn_Off support for i.MX7 (Leonard Crestez)

 - Fix qcom runtime power management error handling (Bjorn Andersson)

 - Update TI dra7xx unaligned access errata workaround for host mode as
   well as endpoint mode (Vignesh R)

 - Fix kirin section mismatch warning (Nathan Chancellor)

 - Remove iproc PAXC slot check to allow VF support (Jitendra Bhivare)

 - Quirk Keystone K2G to limit MRRS to 256 (Kishon Vijay Abraham I)

 - Update Keystone to use MRRS quirk for host bridge instead of open
   coding (Kishon Vijay Abraham I)

 - Refactor Keystone link establishment (Kishon Vijay Abraham I)

 - Simplify and speed up Keystone link training (Kishon Vijay Abraham I)

 - Remove unused Keystone host_init argument (Kishon Vijay Abraham I)

 - Merge Keystone driver files into one (Kishon Vijay Abraham I)

 - Remove redundant Keystone platform_set_drvdata() (Kishon Vijay
   Abraham I)

 - Rename Keystone functions for uniformity (Kishon Vijay Abraham I)

 - Add Keystone device control module DT binding (Kishon Vijay Abraham
   I)

 - Use SYSCON API to get Keystone control module device IDs (Kishon
   Vijay Abraham I)

 - Clean up Keystone PHY handling (Kishon Vijay Abraham I)

 - Use runtime PM APIs to enable Keystone clock (Kishon Vijay Abraham I)

 - Clean up Keystone config space access checks (Kishon Vijay Abraham I)

 - Get Keystone outbound window count from DT (Kishon Vijay Abraham I)

 - Clean up Keystone outbound window configuration (Kishon Vijay Abraham
   I)

 - Clean up Keystone DBI setup (Kishon Vijay Abraham I)

 - Clean up Keystone ks_pcie_link_up() (Kishon Vijay Abraham I)

 - Fix Keystone IRQ status checking (Kishon Vijay Abraham I)

 - Add debug messages for all Keystone errors (Kishon Vijay Abraham I)

 - Clean up Keystone includes and macros (Kishon Vijay Abraham I)

 - Fix Mediatek unchecked return value from devm_pci_remap_iospace()
   (Gustavo A. R. Silva)

 - Fix Mediatek endpoint/port matching logic (Honghui Zhang)

 - Change Mediatek Root Port Class Code to PCI_CLASS_BRIDGE_PCI (Honghui
   Zhang)

 - Remove redundant Mediatek PM domain check (Honghui Zhang)

 - Convert Mediatek to pci_host_probe() (Honghui Zhang)

 - Fix Mediatek MSI enablement (Honghui Zhang)

 - Add Mediatek system PM support for MT2712 and MT7622 (Honghui Zhang)

 - Add Mediatek loadable module support (Honghui Zhang)

 - Detach VMD resources after stopping root bus to prevent orphan
   resources (Jon Derrick)

 - Convert pcitest build process to that used by other tools (iio, perf,
   etc) (Gustavo Pimentel)

* tag 'pci-v4.20-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (140 commits)
  PCI/AER: Refactor error injection fallbacks
  PCI/AER: Abstract AER interrupt handling
  PCI/AER: Reuse existing pcie_port_find_device() interface
  PCI/AER: Use managed resource allocations
  PCI: pcie: Remove redundant 'default n' from Kconfig
  PCI: aardvark: Implement emulated root PCI bridge config space
  PCI: mvebu: Convert to PCI emulated bridge config space
  PCI: mvebu: Drop unused PCI express capability code
  PCI: Introduce PCI bridge emulated config space common logic
  PCI: vmd: Detach resources after stopping root bus
  nvmet: Optionally use PCI P2P memory
  nvmet: Introduce helper functions to allocate and free request SGLs
  nvme-pci: Add support for P2P memory in requests
  nvme-pci: Use PCI p2pmem subsystem to manage the CMB
  IB/core: Ensure we map P2P memory correctly in rdma_rw_ctx_[init|destroy]()
  block: Add PCI P2P flag for request queue
  PCI/P2PDMA: Add P2P DMA driver writer's documentation
  docs-rst: Add a new directory for PCI documentation
  PCI/P2PDMA: Introduce configfs/sysfs enable attribute helpers
  PCI/P2PDMA: Add PCI p2pmem DMA mappings to adjust the bus offset
  ...

8 files changed, 324 insertions, 48 deletions

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 9e4a30b05bd2..2e65be8b1387 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3064,7 +3064,11 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
 	ns->queue = blk_mq_init_queue(ctrl->tagset);
 	if (IS_ERR(ns->queue))
 		goto out_free_ns;
+
 	blk_queue_flag_set(QUEUE_FLAG_NONROT, ns->queue);
+	if (ctrl->ops->flags & NVME_F_PCI_P2PDMA)
+		blk_queue_flag_set(QUEUE_FLAG_PCI_P2PDMA, ns->queue);
+
 	ns->queue->queuedata = ns;
 	ns->ctrl = ctrl;
 
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 9fefba039d1e..cee79cb388af 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -343,6 +343,7 @@ struct nvme_ctrl_ops {
 	unsigned int flags;
 #define NVME_F_FABRICS			(1 << 0)
 #define NVME_F_METADATA_SUPPORTED	(1 << 1)
+#define NVME_F_PCI_P2PDMA		(1 << 2)
 	int (*reg_read32)(struct nvme_ctrl *ctrl, u32 off, u32 *val);
 	int (*reg_write32)(struct nvme_ctrl *ctrl, u32 off, u32 val);
 	int (*reg_read64)(struct nvme_ctrl *ctrl, u32 off, u64 *val);
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 4e023cd007e1..f30031945ee4 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -30,6 +30,7 @@
 #include <linux/types.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/sed-opal.h>
+#include <linux/pci-p2pdma.h>
 
 #include "nvme.h"
 
@@ -99,9 +100,8 @@ struct nvme_dev {
 	struct work_struct remove_work;
 	struct mutex shutdown_lock;
 	bool subsystem;
-	void __iomem *cmb;
-	pci_bus_addr_t cmb_bus_addr;
 	u64 cmb_size;
+	bool cmb_use_sqes;
 	u32 cmbsz;
 	u32 cmbloc;
 	struct nvme_ctrl ctrl;
@@ -158,7 +158,7 @@ struct nvme_queue {
 	struct nvme_dev *dev;
 	spinlock_t sq_lock;
 	struct nvme_command *sq_cmds;
-	struct nvme_command __iomem *sq_cmds_io;
+	bool sq_cmds_is_io;
 	spinlock_t cq_lock ____cacheline_aligned_in_smp;
 	volatile struct nvme_completion *cqes;
 	struct blk_mq_tags **tags;
@@ -447,11 +447,8 @@ static int nvme_pci_map_queues(struct blk_mq_tag_set *set)
 static void nvme_submit_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd)
 {
 	spin_lock(&nvmeq->sq_lock);
-	if (nvmeq->sq_cmds_io)
-		memcpy_toio(&nvmeq->sq_cmds_io[nvmeq->sq_tail], cmd,
-				sizeof(*cmd));
-	else
-		memcpy(&nvmeq->sq_cmds[nvmeq->sq_tail], cmd, sizeof(*cmd));
+
+	memcpy(&nvmeq->sq_cmds[nvmeq->sq_tail], cmd, sizeof(*cmd));
 
 	if (++nvmeq->sq_tail == nvmeq->q_depth)
 		nvmeq->sq_tail = 0;
@@ -748,8 +745,13 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
 		goto out;
 
 	ret = BLK_STS_RESOURCE;
-	nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, dma_dir,
-			DMA_ATTR_NO_WARN);
+
+	if (is_pci_p2pdma_page(sg_page(iod->sg)))
+		nr_mapped = pci_p2pdma_map_sg(dev->dev, iod->sg, iod->nents,
+					  dma_dir);
+	else
+		nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents,
+					     dma_dir,  DMA_ATTR_NO_WARN);
 	if (!nr_mapped)
 		goto out;
 
@@ -791,7 +793,10 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
 			DMA_TO_DEVICE : DMA_FROM_DEVICE;
 
 	if (iod->nents) {
-		dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir);
+		/* P2PDMA requests do not need to be unmapped */
+		if (!is_pci_p2pdma_page(sg_page(iod->sg)))
+			dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir);
+
 		if (blk_integrity_rq(req))
 			dma_unmap_sg(dev->dev, &iod->meta_sg, 1, dma_dir);
 	}
@@ -1232,9 +1237,18 @@ static void nvme_free_queue(struct nvme_queue *nvmeq)
 {
 	dma_free_coherent(nvmeq->q_dmadev, CQ_SIZE(nvmeq->q_depth),
 				(void *)nvmeq->cqes, nvmeq->cq_dma_addr);
-	if (nvmeq->sq_cmds)
-		dma_free_coherent(nvmeq->q_dmadev, SQ_SIZE(nvmeq->q_depth),
-					nvmeq->sq_cmds, nvmeq->sq_dma_addr);
+
+	if (nvmeq->sq_cmds) {
+		if (nvmeq->sq_cmds_is_io)
+			pci_free_p2pmem(to_pci_dev(nvmeq->q_dmadev),
+					nvmeq->sq_cmds,
+					SQ_SIZE(nvmeq->q_depth));
+		else
+			dma_free_coherent(nvmeq->q_dmadev,
+					  SQ_SIZE(nvmeq->q_depth),
+					  nvmeq->sq_cmds,
+					  nvmeq->sq_dma_addr);
+	}
 }
 
 static void nvme_free_queues(struct nvme_dev *dev, int lowest)
@@ -1323,12 +1337,21 @@ static int nvme_cmb_qdepth(struct nvme_dev *dev, int nr_io_queues,
 static int nvme_alloc_sq_cmds(struct nvme_dev *dev, struct nvme_queue *nvmeq,
 				int qid, int depth)
 {
-	/* CMB SQEs will be mapped before creation */
-	if (qid && dev->cmb && use_cmb_sqes && (dev->cmbsz & NVME_CMBSZ_SQS))
-		return 0;
+	struct pci_dev *pdev = to_pci_dev(dev->dev);
+
+	if (qid && dev->cmb_use_sqes && (dev->cmbsz & NVME_CMBSZ_SQS)) {
+		nvmeq->sq_cmds = pci_alloc_p2pmem(pdev, SQ_SIZE(depth));
+		nvmeq->sq_dma_addr = pci_p2pmem_virt_to_bus(pdev,
+						nvmeq->sq_cmds);
+		nvmeq->sq_cmds_is_io = true;
+	}
+
+	if (!nvmeq->sq_cmds) {
+		nvmeq->sq_cmds = dma_alloc_coherent(dev->dev, SQ_SIZE(depth),
+					&nvmeq->sq_dma_addr, GFP_KERNEL);
+		nvmeq->sq_cmds_is_io = false;
+	}
 
-	nvmeq->sq_cmds = dma_alloc_coherent(dev->dev, SQ_SIZE(depth),
-					    &nvmeq->sq_dma_addr, GFP_KERNEL);
 	if (!nvmeq->sq_cmds)
 		return -ENOMEM;
 	return 0;
@@ -1405,13 +1428,6 @@ static int nvme_create_queue(struct nvme_queue *nvmeq, int qid)
 	int result;
 	s16 vector;
 
-	if (dev->cmb && use_cmb_sqes && (dev->cmbsz & NVME_CMBSZ_SQS)) {
-		unsigned offset = (qid - 1) * roundup(SQ_SIZE(nvmeq->q_depth),
-						      dev->ctrl.page_size);
-		nvmeq->sq_dma_addr = dev->cmb_bus_addr + offset;
-		nvmeq->sq_cmds_io = dev->cmb + offset;
-	}
-
 	/*
 	 * A queue's vector matches the queue identifier unless the controller
 	 * has only one vector available.
@@ -1652,9 +1668,6 @@ static void nvme_map_cmb(struct nvme_dev *dev)
 		return;
 	dev->cmbloc = readl(dev->bar + NVME_REG_CMBLOC);
 
-	if (!use_cmb_sqes)
-		return;
-
 	size = nvme_cmb_size_unit(dev) * nvme_cmb_size(dev);
 	offset = nvme_cmb_size_unit(dev) * NVME_CMB_OFST(dev->cmbloc);
 	bar = NVME_CMB_BIR(dev->cmbloc);
@@ -1671,11 +1684,18 @@ static void nvme_map_cmb(struct nvme_dev *dev)
 	if (size > bar_size - offset)
 		size = bar_size - offset;
 
-	dev->cmb = ioremap_wc(pci_resource_start(pdev, bar) + offset, size);
-	if (!dev->cmb)
+	if (pci_p2pdma_add_resource(pdev, bar, size, offset)) {
+		dev_warn(dev->ctrl.device,
+			 "failed to register the CMB\n");
 		return;
-	dev->cmb_bus_addr = pci_bus_address(pdev, bar) + offset;
+	}
+
 	dev->cmb_size = size;
+	dev->cmb_use_sqes = use_cmb_sqes && (dev->cmbsz & NVME_CMBSZ_SQS);
+
+	if ((dev->cmbsz & (NVME_CMBSZ_WDS | NVME_CMBSZ_RDS)) ==
+			(NVME_CMBSZ_WDS | NVME_CMBSZ_RDS))
+		pci_p2pmem_publish(pdev, true);
 
 	if (sysfs_add_file_to_group(&dev->ctrl.device->kobj,
 				    &dev_attr_cmb.attr, NULL))
@@ -1685,12 +1705,10 @@ static void nvme_map_cmb(struct nvme_dev *dev)
 
 static inline void nvme_release_cmb(struct nvme_dev *dev)
 {
-	if (dev->cmb) {
-		iounmap(dev->cmb);
-		dev->cmb = NULL;
+	if (dev->cmb_size) {
 		sysfs_remove_file_from_group(&dev->ctrl.device->kobj,
 					     &dev_attr_cmb.attr, NULL);
-		dev->cmbsz = 0;
+		dev->cmb_size = 0;
 	}
 }
 
@@ -1889,13 +1907,13 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
 	if (nr_io_queues == 0)
 		return 0;
 
-	if (dev->cmb && (dev->cmbsz & NVME_CMBSZ_SQS)) {
+	if (dev->cmb_use_sqes) {
 		result = nvme_cmb_qdepth(dev, nr_io_queues,
 				sizeof(struct nvme_command));
 		if (result > 0)
 			dev->q_depth = result;
 		else
-			nvme_release_cmb(dev);
+			dev->cmb_use_sqes = false;
 	}
 
 	do {
@@ -2390,7 +2408,8 @@ static int nvme_pci_get_address(struct nvme_ctrl *ctrl, char *buf, int size)
 static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = {
 	.name			= "pcie",
 	.module			= THIS_MODULE,
-	.flags			= NVME_F_METADATA_SUPPORTED,
+	.flags			= NVME_F_METADATA_SUPPORTED |
+				  NVME_F_PCI_P2PDMA,
 	.reg_read32		= nvme_pci_reg_read32,
 	.reg_write32		= nvme_pci_reg_write32,
 	.reg_read64		= nvme_pci_reg_read64,
@@ -2648,7 +2667,6 @@ static void nvme_error_resume(struct pci_dev *pdev)
 	struct nvme_dev *dev = pci_get_drvdata(pdev);
 
 	flush_work(&dev->ctrl.reset_work);
-	pci_cleanup_aer_uncorrect_error_status(pdev);
 }
 
 static const struct pci_error_handlers nvme_err_handler = {
diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index b37a8e3e3f80..d895579b6c5d 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -17,6 +17,8 @@
 #include <linux/slab.h>
 #include <linux/stat.h>
 #include <linux/ctype.h>
+#include <linux/pci.h>
+#include <linux/pci-p2pdma.h>
 
 #include "nvmet.h"
 
@@ -340,6 +342,48 @@ out_unlock:
 
 CONFIGFS_ATTR(nvmet_ns_, device_path);
 
+#ifdef CONFIG_PCI_P2PDMA
+static ssize_t nvmet_ns_p2pmem_show(struct config_item *item, char *page)
+{
+	struct nvmet_ns *ns = to_nvmet_ns(item);
+
+	return pci_p2pdma_enable_show(page, ns->p2p_dev, ns->use_p2pmem);
+}
+
+static ssize_t nvmet_ns_p2pmem_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_ns *ns = to_nvmet_ns(item);
+	struct pci_dev *p2p_dev = NULL;
+	bool use_p2pmem;
+	int ret = count;
+	int error;
+
+	mutex_lock(&ns->subsys->lock);
+	if (ns->enabled) {
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+
+	error = pci_p2pdma_enable_store(page, &p2p_dev, &use_p2pmem);
+	if (error) {
+		ret = error;
+		goto out_unlock;
+	}
+
+	ns->use_p2pmem = use_p2pmem;
+	pci_dev_put(ns->p2p_dev);
+	ns->p2p_dev = p2p_dev;
+
+out_unlock:
+	mutex_unlock(&ns->subsys->lock);
+
+	return ret;
+}
+
+CONFIGFS_ATTR(nvmet_ns_, p2pmem);
+#endif /* CONFIG_PCI_P2PDMA */
+
 static ssize_t nvmet_ns_device_uuid_show(struct config_item *item, char *page)
 {
 	return sprintf(page, "%pUb\n", &to_nvmet_ns(item)->uuid);
@@ -509,6 +553,9 @@ static struct configfs_attribute *nvmet_ns_attrs[] = {
 	&nvmet_ns_attr_ana_grpid,
 	&nvmet_ns_attr_enable,
 	&nvmet_ns_attr_buffered_io,
+#ifdef CONFIG_PCI_P2PDMA
+	&nvmet_ns_attr_p2pmem,
+#endif
 	NULL,
 };
 
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 0acdff9e6842..f4efe289dc7b 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -15,6 +15,7 @@
 #include <linux/module.h>
 #include <linux/random.h>
 #include <linux/rculist.h>
+#include <linux/pci-p2pdma.h>
 
 #include "nvmet.h"
 
@@ -365,9 +366,93 @@ static void nvmet_ns_dev_disable(struct nvmet_ns *ns)
 	nvmet_file_ns_disable(ns);
 }
 
+static int nvmet_p2pmem_ns_enable(struct nvmet_ns *ns)
+{
+	int ret;
+	struct pci_dev *p2p_dev;
+
+	if (!ns->use_p2pmem)
+		return 0;
+
+	if (!ns->bdev) {
+		pr_err("peer-to-peer DMA is not supported by non-block device namespaces\n");
+		return -EINVAL;
+	}
+
+	if (!blk_queue_pci_p2pdma(ns->bdev->bd_queue)) {
+		pr_err("peer-to-peer DMA is not supported by the driver of %s\n",
+		       ns->device_path);
+		return -EINVAL;
+	}
+
+	if (ns->p2p_dev) {
+		ret = pci_p2pdma_distance(ns->p2p_dev, nvmet_ns_dev(ns), true);
+		if (ret < 0)
+			return -EINVAL;
+	} else {
+		/*
+		 * Right now we just check that there is p2pmem available so
+		 * we can report an error to the user right away if there
+		 * is not. We'll find the actual device to use once we
+		 * setup the controller when the port's device is available.
+		 */
+
+		p2p_dev = pci_p2pmem_find(nvmet_ns_dev(ns));
+		if (!p2p_dev) {
+			pr_err("no peer-to-peer memory is available for %s\n",
+			       ns->device_path);
+			return -EINVAL;
+		}
+
+		pci_dev_put(p2p_dev);
+	}
+
+	return 0;
+}
+
+/*
+ * Note: ctrl->subsys->lock should be held when calling this function
+ */
+static void nvmet_p2pmem_ns_add_p2p(struct nvmet_ctrl *ctrl,
+				    struct nvmet_ns *ns)
+{
+	struct device *clients[2];
+	struct pci_dev *p2p_dev;
+	int ret;
+
+	if (!ctrl->p2p_client)
+		return;
+
+	if (ns->p2p_dev) {
+		ret = pci_p2pdma_distance(ns->p2p_dev, ctrl->p2p_client, true);
+		if (ret < 0)
+			return;
+
+		p2p_dev = pci_dev_get(ns->p2p_dev);
+	} else {
+		clients[0] = ctrl->p2p_client;
+		clients[1] = nvmet_ns_dev(ns);
+
+		p2p_dev = pci_p2pmem_find_many(clients, ARRAY_SIZE(clients));
+		if (!p2p_dev) {
+			pr_err("no peer-to-peer memory is available that's supported by %s and %s\n",
+			       dev_name(ctrl->p2p_client), ns->device_path);
+			return;
+		}
+	}
+
+	ret = radix_tree_insert(&ctrl->p2p_ns_map, ns->nsid, p2p_dev);
+	if (ret < 0)
+		pci_dev_put(p2p_dev);
+
+	pr_info("using p2pmem on %s for nsid %d\n", pci_name(p2p_dev),
+		ns->nsid);
+}
+
 int nvmet_ns_enable(struct nvmet_ns *ns)
 {
 	struct nvmet_subsys *subsys = ns->subsys;
+	struct nvmet_ctrl *ctrl;
 	int ret;
 
 	mutex_lock(&subsys->lock);
@@ -384,6 +469,13 @@ int nvmet_ns_enable(struct nvmet_ns *ns)
 	if (ret)
 		goto out_unlock;
 
+	ret = nvmet_p2pmem_ns_enable(ns);
+	if (ret)
+		goto out_unlock;
+
+	list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry)
+		nvmet_p2pmem_ns_add_p2p(ctrl, ns);
+
 	ret = percpu_ref_init(&ns->ref, nvmet_destroy_namespace,
 				0, GFP_KERNEL);
 	if (ret)
@@ -418,6 +510,9 @@ out_unlock:
 	mutex_unlock(&subsys->lock);
 	return ret;
 out_dev_put:
+	list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry)
+		pci_dev_put(radix_tree_delete(&ctrl->p2p_ns_map, ns->nsid));
+
 	nvmet_ns_dev_disable(ns);
 	goto out_unlock;
 }
@@ -425,6 +520,7 @@ out_dev_put:
 void nvmet_ns_disable(struct nvmet_ns *ns)
 {
 	struct nvmet_subsys *subsys = ns->subsys;
+	struct nvmet_ctrl *ctrl;
 
 	mutex_lock(&subsys->lock);
 	if (!ns->enabled)
@@ -434,6 +530,10 @@ void nvmet_ns_disable(struct nvmet_ns *ns)
 	list_del_rcu(&ns->dev_link);
 	if (ns->nsid == subsys->max_nsid)
 		subsys->max_nsid = nvmet_max_nsid(subsys);
+
+	list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry)
+		pci_dev_put(radix_tree_delete(&ctrl->p2p_ns_map, ns->nsid));
+
 	mutex_unlock(&subsys->lock);
 
 	/*
@@ -450,6 +550,7 @@ void nvmet_ns_disable(struct nvmet_ns *ns)
 	percpu_ref_exit(&ns->ref);
 
 	mutex_lock(&subsys->lock);
+
 	subsys->nr_namespaces--;
 	nvmet_ns_changed(subsys, ns->nsid);
 	nvmet_ns_dev_disable(ns);
@@ -725,6 +826,51 @@ void nvmet_req_execute(struct nvmet_req *req)
 }
 EXPORT_SYMBOL_GPL(nvmet_req_execute);
 
+int nvmet_req_alloc_sgl(struct nvmet_req *req)
+{
+	struct pci_dev *p2p_dev = NULL;
+
+	if (IS_ENABLED(CONFIG_PCI_P2PDMA)) {
+		if (req->sq->ctrl && req->ns)
+			p2p_dev = radix_tree_lookup(&req->sq->ctrl->p2p_ns_map,
+						    req->ns->nsid);
+
+		req->p2p_dev = NULL;
+		if (req->sq->qid && p2p_dev) {
+			req->sg = pci_p2pmem_alloc_sgl(p2p_dev, &req->sg_cnt,
+						       req->transfer_len);
+			if (req->sg) {
+				req->p2p_dev = p2p_dev;
+				return 0;
+			}
+		}
+
+		/*
+		 * If no P2P memory was available we fallback to using
+		 * regular memory
+		 */
+	}
+
+	req->sg = sgl_alloc(req->transfer_len, GFP_KERNEL, &req->sg_cnt);
+	if (!req->sg)
+		return -ENOMEM;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nvmet_req_alloc_sgl);
+
+void nvmet_req_free_sgl(struct nvmet_req *req)
+{
+	if (req->p2p_dev)
+		pci_p2pmem_free_sgl(req->p2p_dev, req->sg);
+	else
+		sgl_free(req->sg);
+
+	req->sg = NULL;
+	req->sg_cnt = 0;
+}
+EXPORT_SYMBOL_GPL(nvmet_req_free_sgl);
+
 static inline bool nvmet_cc_en(u32 cc)
 {
 	return (cc >> NVME_CC_EN_SHIFT) & 0x1;
@@ -921,6 +1067,37 @@ bool nvmet_host_allowed(struct nvmet_req *req, struct nvmet_subsys *subsys,
 		return __nvmet_host_allowed(subsys, hostnqn);
 }
 
+/*
+ * Note: ctrl->subsys->lock should be held when calling this function
+ */
+static void nvmet_setup_p2p_ns_map(struct nvmet_ctrl *ctrl,
+		struct nvmet_req *req)
+{
+	struct nvmet_ns *ns;
+
+	if (!req->p2p_client)
+		return;
+
+	ctrl->p2p_client = get_device(req->p2p_client);
+
+	list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link)
+		nvmet_p2pmem_ns_add_p2p(ctrl, ns);
+}
+
+/*
+ * Note: ctrl->subsys->lock should be held when calling this function
+ */
+static void nvmet_release_p2p_ns_map(struct nvmet_ctrl *ctrl)
+{
+	struct radix_tree_iter iter;
+	void __rcu **slot;
+
+	radix_tree_for_each_slot(slot, &ctrl->p2p_ns_map, &iter, 0)
+		pci_dev_put(radix_tree_deref_slot(slot));
+
+	put_device(ctrl->p2p_client);
+}
+
 u16 nvmet_alloc_ctrl(const char *subsysnqn, const char *hostnqn,
 		struct nvmet_req *req, u32 kato, struct nvmet_ctrl **ctrlp)
 {
@@ -962,6 +1139,7 @@ u16 nvmet_alloc_ctrl(const char *subsysnqn, const char *hostnqn,
 
 	INIT_WORK(&ctrl->async_event_work, nvmet_async_event_work);
 	INIT_LIST_HEAD(&ctrl->async_events);
+	INIT_RADIX_TREE(&ctrl->p2p_ns_map, GFP_KERNEL);
 
 	memcpy(ctrl->subsysnqn, subsysnqn, NVMF_NQN_SIZE);
 	memcpy(ctrl->hostnqn, hostnqn, NVMF_NQN_SIZE);
@@ -1026,6 +1204,7 @@ u16 nvmet_alloc_ctrl(const char *subsysnqn, const char *hostnqn,
 
 	mutex_lock(&subsys->lock);
 	list_add_tail(&ctrl->subsys_entry, &subsys->ctrls);
+	nvmet_setup_p2p_ns_map(ctrl, req);
 	mutex_unlock(&subsys->lock);
 
 	*ctrlp = ctrl;
@@ -1053,6 +1232,7 @@ static void nvmet_ctrl_free(struct kref *ref)
 	struct nvmet_subsys *subsys = ctrl->subsys;
 
 	mutex_lock(&subsys->lock);
+	nvmet_release_p2p_ns_map(ctrl);
 	list_del(&ctrl->subsys_entry);
 	mutex_unlock(&subsys->lock);
 
diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index f93fb5711142..c1ec3475a140 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -78,6 +78,9 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
 		op = REQ_OP_READ;
 	}
 
+	if (is_pci_p2pdma_page(sg_page(req->sg)))
+		op_flags |= REQ_NOMERGE;
+
 	sector = le64_to_cpu(req->cmd->rw.slba);
 	sector <<= (req->ns->blksize_shift - 9);
 
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 08f7b57a1203..c2b4d9ee6391 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -26,6 +26,7 @@
 #include <linux/configfs.h>
 #include <linux/rcupdate.h>
 #include <linux/blkdev.h>
+#include <linux/radix-tree.h>
 
 #define NVMET_ASYNC_EVENTS		4
 #define NVMET_ERROR_LOG_SLOTS		128
@@ -77,6 +78,9 @@ struct nvmet_ns {
 	struct completion	disable_done;
 	mempool_t		*bvec_pool;
 	struct kmem_cache	*bvec_cache;
+
+	int			use_p2pmem;
+	struct pci_dev		*p2p_dev;
 };
 
 static inline struct nvmet_ns *to_nvmet_ns(struct config_item *item)
@@ -84,6 +88,11 @@ static inline struct nvmet_ns *to_nvmet_ns(struct config_item *item)
 	return container_of(to_config_group(item), struct nvmet_ns, group);
 }
 
+static inline struct device *nvmet_ns_dev(struct nvmet_ns *ns)
+{
+	return ns->bdev ? disk_to_dev(ns->bdev->bd_disk) : NULL;
+}
+
 struct nvmet_cq {
 	u16			qid;
 	u16			size;
@@ -184,6 +193,9 @@ struct nvmet_ctrl {
 
 	char			subsysnqn[NVMF_NQN_FIELD_LEN];
 	char			hostnqn[NVMF_NQN_FIELD_LEN];
+
+	struct device *p2p_client;
+	struct radix_tree_root p2p_ns_map;
 };
 
 struct nvmet_subsys {
@@ -295,6 +307,9 @@ struct nvmet_req {
 
 	void (*execute)(struct nvmet_req *req);
 	const struct nvmet_fabrics_ops *ops;
+
+	struct pci_dev *p2p_dev;
+	struct device *p2p_client;
 };
 
 extern struct workqueue_struct *buffered_io_wq;
@@ -337,6 +352,8 @@ bool nvmet_req_init(struct nvmet_req *req, struct nvmet_cq *cq,
 void nvmet_req_uninit(struct nvmet_req *req);
 void nvmet_req_execute(struct nvmet_req *req);
 void nvmet_req_complete(struct nvmet_req *req, u16 status);
+int nvmet_req_alloc_sgl(struct nvmet_req *req);
+void nvmet_req_free_sgl(struct nvmet_req *req);
 
 void nvmet_cq_setup(struct nvmet_ctrl *ctrl, struct nvmet_cq *cq, u16 qid,
 		u16 size);
diff --git a/drivers/nvme/target/rdma.c b/drivers/nvme/target/rdma.c
index bd265aceb90c..ddce100be57a 100644
--- a/drivers/nvme/target/rdma.c
+++ b/drivers/nvme/target/rdma.c
@@ -504,7 +504,7 @@ static void nvmet_rdma_release_rsp(struct nvmet_rdma_rsp *rsp)
 	}
 
 	if (rsp->req.sg != rsp->cmd->inline_sg)
-		sgl_free(rsp->req.sg);
+		nvmet_req_free_sgl(&rsp->req);
 
 	if (unlikely(!list_empty_careful(&queue->rsp_wr_wait_list)))
 		nvmet_rdma_process_wr_wait_list(queue);
@@ -653,24 +653,24 @@ static u16 nvmet_rdma_map_sgl_keyed(struct nvmet_rdma_rsp *rsp,
 {
 	struct rdma_cm_id *cm_id = rsp->queue->cm_id;
 	u64 addr = le64_to_cpu(sgl->addr);
-	u32 len = get_unaligned_le24(sgl->length);
 	u32 key = get_unaligned_le32(sgl->key);
 	int ret;
 
+	rsp->req.transfer_len = get_unaligned_le24(sgl->length);
+
 	/* no data command? */
-	if (!len)
+	if (!rsp->req.transfer_len)
 		return 0;
 
-	rsp->req.sg = sgl_alloc(len, GFP_KERNEL, &rsp->req.sg_cnt);
-	if (!rsp->req.sg)
-		return NVME_SC_INTERNAL;
+	ret = nvmet_req_alloc_sgl(&rsp->req);
+	if (ret < 0)
+		goto error_out;
 
 	ret = rdma_rw_ctx_init(&rsp->rw, cm_id->qp, cm_id->port_num,
 			rsp->req.sg, rsp->req.sg_cnt, 0, addr, key,
 			nvmet_data_dir(&rsp->req));
 	if (ret < 0)
-		return NVME_SC_INTERNAL;
-	rsp->req.transfer_len += len;
+		goto error_out;
 	rsp->n_rdma += ret;
 
 	if (invalidate) {
@@ -679,6 +679,10 @@ static u16 nvmet_rdma_map_sgl_keyed(struct nvmet_rdma_rsp *rsp,
 	}
 
 	return 0;
+
+error_out:
+	rsp->req.transfer_len = 0;
+	return NVME_SC_INTERNAL;
 }
 
 static u16 nvmet_rdma_map_sgl(struct nvmet_rdma_rsp *rsp)
@@ -746,6 +750,8 @@ static void nvmet_rdma_handle_command(struct nvmet_rdma_queue *queue,
 		cmd->send_sge.addr, cmd->send_sge.length,
 		DMA_TO_DEVICE);
 
+	cmd->req.p2p_client = &queue->dev->device->dev;
+
 	if (!nvmet_req_init(&cmd->req, &queue->nvme_cq,
 			&queue->nvme_sq, &nvmet_rdma_ops))
 		return;