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

Ira Weiny
2019-06-26T18:01:22Z

On Wed, Jun 26, 2019 at 02:27:07PM +0200, Christoph Hellwig wrote:
> 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>

Reviewed-by: Ira Weiny <ira.weiny@intel.com>

> ---
> 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
>
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