[PATCH 08/25] memremap: validate the pagemap type passed to devm_memremap_pages

Christoph Hellwig
2019-06-26T12:27:52Z

Most pgmap types are only supported when certain config options are
enabled. Check for a type that is valid for the current configuration
before setting up the pagemap. For this the usage of the 0 type for
device dax gets replaced with an explicit MEMORY_DEVICE_DEVDAX type.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/dax/device.c | 1 +
include/linux/memremap.h | 8 ++++++++
kernel/memremap.c | 22 ++++++++++++++++++++++
3 files changed, 31 insertions(+)

diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index 8465d12fecba..79014baa782d 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -468,6 +468,7 @@ int dev_dax_probe(struct device *dev)
dev_dax->pgmap.ref = &dev_dax->ref;
dev_dax->pgmap.kill = dev_dax_percpu_kill;
dev_dax->pgmap.cleanup = dev_dax_percpu_exit;
+ dev_dax->pgmap.type = MEMORY_DEVICE_DEVDAX;
addr = devm_memremap_pages(dev, &dev_dax->pgmap);
if (IS_ERR(addr))
return PTR_ERR(addr);
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 995c62c5a48b..0c86f2c5ac9c 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -45,13 +45,21 @@ struct vmem_altmap {
* wakeup is used to coordinate physical address space management (ex:
* fs truncate/hole punch) vs pinned pages (ex: device dma).
*
+ * MEMORY_DEVICE_DEVDAX:
+ * Host memory that has similar access semantics as System RAM i.e. DMA
+ * coherent and supports page pinning. In contrast to
+ * MEMORY_DEVICE_FS_DAX, this memory is access via a device-dax
+ * character device.
+ *
* MEMORY_DEVICE_PCI_P2PDMA:
* Device memory residing in a PCI BAR intended for use with Peer-to-Peer
* transactions.
*/
enum memory_type {
+ /* 0 is reserved to catch uninitialized type fields */
MEMORY_DEVICE_PRIVATE = 1,
MEMORY_DEVICE_FS_DAX,
+ MEMORY_DEVICE_DEVDAX,
MEMORY_DEVICE_PCI_P2PDMA,
};

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 6e1970719dc2..abda62d1e5a3 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -157,6 +157,28 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
pgprot_t pgprot = PAGE_KERNEL;
int error, nid, is_ram;

+ switch (pgmap->type) {
+ case MEMORY_DEVICE_PRIVATE:
+ if (!IS_ENABLED(CONFIG_DEVICE_PRIVATE)) {
+ WARN(1, "Device private memory not supported\n");
+ return ERR_PTR(-EINVAL);
+ }
+ break;
+ case MEMORY_DEVICE_FS_DAX:
+ if (!IS_ENABLED(CONFIG_ZONE_DEVICE) ||
+ IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {
+ WARN(1, "File system DAX not supported\n");
+ return ERR_PTR(-EINVAL);
+ }
+ break;
+ case MEMORY_DEVICE_DEVDAX:
+ case MEMORY_DEVICE_PCI_P2PDMA:
+ break;
+ default:
+ WARN(1, "Invalid pgmap type %d\n", pgmap->type);
+ break;
+ }
+
if (!pgmap->ref || !pgmap->kill || !pgmap->cleanup) {
WARN(1, "Missing reference count teardown definition\n");
return ERR_PTR(-EINVAL);
--
2.20.1