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Date: Fri, 6 Nov 2020 10:00:35 -0700
From: Logan Gunthorpe <logang@...tatee.com>
To: linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
linux-block@...r.kernel.org, linux-pci@...r.kernel.org,
linux-mm@...ck.org, iommu@...ts.linux-foundation.org
Cc: Stephen Bates <sbates@...thlin.com>,
Christoph Hellwig <hch@....de>,
Dan Williams <dan.j.williams@...el.com>,
Jason Gunthorpe <jgg@...pe.ca>,
Christian König <christian.koenig@....com>,
Ira Weiny <iweiny@...el.com>,
John Hubbard <jhubbard@...dia.com>,
Don Dutile <ddutile@...hat.com>,
Matthew Wilcox <willy@...radead.org>,
Daniel Vetter <daniel.vetter@...ll.ch>,
Logan Gunthorpe <logang@...tatee.com>
Subject: [RFC PATCH 14/15] PCI/P2PDMA: Introduce pci_mmap_p2pmem()
Introduce pci_mmap_p2pmem() which is a helper to allocate and mmap
a hunk of p2pmem into userspace.
Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
drivers/pci/p2pdma.c | 104 +++++++++++++++++++++++++++++++++++++
include/linux/pci-p2pdma.h | 6 +++
2 files changed, 110 insertions(+)
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 9961e779f430..8eab53ac59ae 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -16,6 +16,7 @@
#include <linux/genalloc.h>
#include <linux/memremap.h>
#include <linux/percpu-refcount.h>
+#include <linux/pfn_t.h>
#include <linux/random.h>
#include <linux/seq_buf.h>
#include <linux/xarray.h>
@@ -1055,3 +1056,106 @@ ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev,
return sprintf(page, "%s\n", pci_name(p2p_dev));
}
EXPORT_SYMBOL_GPL(pci_p2pdma_enable_show);
+
+struct pci_p2pdma_map {
+ struct kref ref;
+ struct pci_dev *pdev;
+ void *kaddr;
+ size_t len;
+};
+
+static struct pci_p2pdma_map *pci_p2pdma_map_alloc(struct pci_dev *pdev,
+ size_t len)
+{
+ struct pci_p2pdma_map *pmap;
+
+ pmap = kzalloc(sizeof(*pmap), GFP_KERNEL);
+ if (!pmap)
+ return NULL;
+
+ kref_init(&pmap->ref);
+ pmap->pdev = pdev;
+ pmap->len = len;
+
+ pmap->kaddr = pci_alloc_p2pmem(pdev, len);
+ if (!pmap->kaddr) {
+ kfree(pmap);
+ return NULL;
+ }
+
+ return pmap;
+}
+
+static void pci_p2pdma_map_free(struct kref *ref)
+{
+ struct pci_p2pdma_map *pmap =
+ container_of(ref, struct pci_p2pdma_map, ref);
+
+ pci_free_p2pmem(pmap->pdev, pmap->kaddr, pmap->len);
+ kfree(pmap);
+}
+
+static void pci_p2pdma_vma_open(struct vm_area_struct *vma)
+{
+ struct pci_p2pdma_map *pmap = vma->vm_private_data;
+
+ kref_get(&pmap->ref);
+}
+
+static void pci_p2pdma_vma_close(struct vm_area_struct *vma)
+{
+ struct pci_p2pdma_map *pmap = vma->vm_private_data;
+
+ kref_put(&pmap->ref, pci_p2pdma_map_free);
+}
+
+const struct vm_operations_struct pci_p2pdma_vmops = {
+ .open = pci_p2pdma_vma_open,
+ .close = pci_p2pdma_vma_close,
+};
+
+/**
+ * pci_mmap_p2pmem - allocate peer-to-peer DMA memory
+ * @pdev: the device to allocate memory from
+ * @vma: the userspace vma to map the memory to
+ *
+ * Returns 0 on success, or a negative error code on failure
+ */
+int pci_mmap_p2pmem(struct pci_dev *pdev, struct vm_area_struct *vma)
+{
+ struct pci_p2pdma_map *pmap;
+ unsigned long addr, pfn;
+ vm_fault_t ret;
+
+ /* prevent private mappings from being established */
+ if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
+ pci_info_ratelimited(pdev,
+ "%s: fail, attempted private mapping\n",
+ current->comm);
+ return -EINVAL;
+ }
+
+ pmap = pci_p2pdma_map_alloc(pdev, vma->vm_end - vma->vm_start);
+ if (!pmap)
+ return -ENOMEM;
+
+ vma->vm_flags |= VM_MIXEDMAP;
+ vma->vm_private_data = pmap;
+ vma->vm_ops = &pci_p2pdma_vmops;
+
+ pfn = virt_to_phys(pmap->kaddr) >> PAGE_SHIFT;
+ for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) {
+ ret = vmf_insert_mixed(vma, addr,
+ __pfn_to_pfn_t(pfn, PFN_DEV | PFN_MAP));
+ if (ret & VM_FAULT_ERROR)
+ goto out_error;
+ pfn++;
+ }
+
+ return 0;
+
+out_error:
+ kref_put(&pmap->ref, pci_p2pdma_map_free);
+ return -EFAULT;
+}
+EXPORT_SYMBOL_GPL(pci_mmap_p2pmem);
diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h
index fc5de47eeac4..26fe40363d1c 100644
--- a/include/linux/pci-p2pdma.h
+++ b/include/linux/pci-p2pdma.h
@@ -40,6 +40,7 @@ int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev,
bool *use_p2pdma);
ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev,
bool use_p2pdma);
+int pci_mmap_p2pmem(struct pci_dev *pdev, struct vm_area_struct *vma);
#else /* CONFIG_PCI_P2PDMA */
static inline int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar,
size_t size, u64 offset)
@@ -116,6 +117,11 @@ static inline ssize_t pci_p2pdma_enable_show(char *page,
{
return sprintf(page, "none\n");
}
+static inline int pci_mmap_p2pmem(struct pci_dev *pdev,
+ struct vm_area_struct *vma)
+{
+ return -EOPNOTSUPP;
+}
#endif /* CONFIG_PCI_P2PDMA */
--
2.20.1
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