add a not device managed memremap_pages v2

add a not device managed memremap_pages v2

[Christoph Hellwig]

Hi Dan and Jason,

Bharata has been working on secure page management for kvmppc guests,
and one I thing I noticed is that he had to fake up a struct device
just so that it could be passed to the devm_memremap_pages
instrastructure for device private memory.

This series adds non-device managed versions of the
devm_request_free_mem_region and devm_memremap_pages functions for
his use case.

Changes since v1:
 - don't overload devm_request_free_mem_region
 - export the memremap_pages and munmap_pages as kvmppc can be a module

[PATCH 1/4] resource: add a not device managed request_free_mem_region variant

[Christoph Hellwig]

Just add a simple macro that passes a NULL dev argument to
dev_request_free_mem_region, and call request_mem_region in the
function for that particular case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/ioport.h |  2 ++
 kernel/resource.c      | 45 +++++++++++++++++++++++++++++-------------
 2 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 5b6a7121c9f0..7bddddfc76d6 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -297,6 +297,8 @@ static inline bool resource_overlaps(struct resource *r1, struct resource *r2)
 
 struct resource *devm_request_free_mem_region(struct device *dev,
 		struct resource *base, unsigned long size);
+struct resource *request_free_mem_region(struct resource *base,
+		unsigned long size, const char *name);
 
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */
diff --git a/kernel/resource.c b/kernel/resource.c
index 7ea4306503c5..74877e9d90ca 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1644,19 +1644,8 @@ void resource_list_free(struct list_head *head)
 EXPORT_SYMBOL(resource_list_free);
 
 #ifdef CONFIG_DEVICE_PRIVATE
-/**
- * devm_request_free_mem_region - find free region for device private memory
- *
- * @dev: device struct to bind the resource to
- * @size: size in bytes of the device memory to add
- * @base: resource tree to look in
- *
- * This function tries to find an empty range of physical address big enough to
- * contain the new resource, so that it can later be hotplugged as ZONE_DEVICE
- * memory, which in turn allocates struct pages.
- */
-struct resource *devm_request_free_mem_region(struct device *dev,
-		struct resource *base, unsigned long size)
+static struct resource *__request_free_mem_region(struct device *dev,
+		struct resource *base, unsigned long size, const char *name)
 {
 	resource_size_t end, addr;
 	struct resource *res;
@@ -1670,7 +1659,10 @@ struct resource *devm_request_free_mem_region(struct device *dev,
 				REGION_DISJOINT)
 			continue;
 
-		res = devm_request_mem_region(dev, addr, size, dev_name(dev));
+		if (dev)
+			res = devm_request_mem_region(dev, addr, size, name);
+		else
+			res = request_mem_region(addr, size, name);
 		if (!res)
 			return ERR_PTR(-ENOMEM);
 		res->desc = IORES_DESC_DEVICE_PRIVATE_MEMORY;
@@ -1679,7 +1671,32 @@ struct resource *devm_request_free_mem_region(struct device *dev,
 
 	return ERR_PTR(-ERANGE);
 }
+
+/**
+ * devm_request_free_mem_region - find free region for device private memory
+ *
+ * @dev: device struct to bind the resource to
+ * @size: size in bytes of the device memory to add
+ * @base: resource tree to look in
+ *
+ * This function tries to find an empty range of physical address big enough to
+ * contain the new resource, so that it can later be hotplugged as ZONE_DEVICE
+ * memory, which in turn allocates struct pages.
+ */
+struct resource *devm_request_free_mem_region(struct device *dev,
+		struct resource *base, unsigned long size)
+{
+	return __request_free_mem_region(dev, base, size, dev_name(dev));
+}
 EXPORT_SYMBOL_GPL(devm_request_free_mem_region);
+
+struct resource *request_free_mem_region(struct resource *base,
+		unsigned long size, const char *name)
+{
+	return __request_free_mem_region(NULL, base, size, name);
+}
+EXPORT_SYMBOL_GPL(request_free_mem_region);
+
 #endif /* CONFIG_DEVICE_PRIVATE */
 
 static int __init strict_iomem(char *str)
-- 
2.20.1

Re: [PATCH 1/4] resource: add a not device managed request_free_mem_region variant

[Andrew Morton]

On Fri, 16 Aug 2019 08:54:31 +0200 Christoph Hellwig <hch@lst.de> wrote:

> Just add a simple macro that passes a NULL dev argument to
> dev_request_free_mem_region, and call request_mem_region in the
> function for that particular case.

Nit:

> +struct resource *request_free_mem_region(struct resource *base,
> +		unsigned long size, const char *name);

This isn't a macro ;)

Re: [PATCH 1/4] resource: add a not device managed request_free_mem_region variant

[Christoph Hellwig]

On Fri, Aug 16, 2019 at 02:01:34PM -0700, Andrew Morton wrote:
> On Fri, 16 Aug 2019 08:54:31 +0200 Christoph Hellwig <hch@lst.de> wrote:
> 
> > Just add a simple macro that passes a NULL dev argument to
> > dev_request_free_mem_region, and call request_mem_region in the
> > function for that particular case.
> 
> Nit:
> 
> > +struct resource *request_free_mem_region(struct resource *base,
> > +		unsigned long size, const char *name);
> 
> This isn't a macro ;)

Oops, the changelog needs updating vs the first version of course.

[PATCH 2/4] memremap: remove the dev field in struct dev_pagemap

[Christoph Hellwig]

The dev field in struct dev_pagemap is only used to print dev_name in
two places, which are at best nice to have.  Just remove the field
and thus the name in those two messages.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/memremap.h | 1 -
 mm/memremap.c            | 6 +-----
 mm/page_alloc.c          | 2 +-
 3 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index f8a5b2a19945..8f0013e18e14 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -109,7 +109,6 @@ struct dev_pagemap {
 	struct percpu_ref *ref;
 	struct percpu_ref internal_ref;
 	struct completion done;
-	struct device *dev;
 	enum memory_type type;
 	unsigned int flags;
 	u64 pci_p2pdma_bus_offset;
diff --git a/mm/memremap.c b/mm/memremap.c
index 86432650f829..416b4129acbb 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -102,7 +102,6 @@ static void dev_pagemap_cleanup(struct dev_pagemap *pgmap)
 static void devm_memremap_pages_release(void *data)
 {
 	struct dev_pagemap *pgmap = data;
-	struct device *dev = pgmap->dev;
 	struct resource *res = &pgmap->res;
 	unsigned long pfn;
 	int nid;
@@ -129,8 +128,7 @@ static void devm_memremap_pages_release(void *data)
 
 	untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
 	pgmap_array_delete(res);
-	dev_WARN_ONCE(dev, pgmap->altmap.alloc,
-		      "%s: failed to free all reserved pages\n", __func__);
+	WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
 }
 
 static void dev_pagemap_percpu_release(struct percpu_ref *ref)
@@ -251,8 +249,6 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 		goto err_array;
 	}
 
-	pgmap->dev = dev;
-
 	error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(res->start),
 				PHYS_PFN(res->end), pgmap, GFP_KERNEL));
 	if (error)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 272c6de1bf4e..b39baa2b1faf 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5982,7 +5982,7 @@ void __ref memmap_init_zone_device(struct zone *zone,
 		}
 	}
 
-	pr_info("%s initialised, %lu pages in %ums\n", dev_name(pgmap->dev),
+	pr_info("%s initialised %lu pages in %ums\n", __func__,
 		size, jiffies_to_msecs(jiffies - start));
 }
 
-- 
2.20.1

[PATCH 3/4] memremap: don't use a separate devm action for devmap_managed_enable_get

[Christoph Hellwig]

Just clean up for early failures and then piggy back on
devm_memremap_pages_release.  This helps with a pending not device
managed version of devm_memremap_pages.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/memremap.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/mm/memremap.c b/mm/memremap.c
index 416b4129acbb..4e11da4ecab9 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -21,13 +21,13 @@ DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
 EXPORT_SYMBOL(devmap_managed_key);
 static atomic_t devmap_managed_enable;
 
-static void devmap_managed_enable_put(void *data)
+static void devmap_managed_enable_put(void)
 {
 	if (atomic_dec_and_test(&devmap_managed_enable))
 		static_branch_disable(&devmap_managed_key);
 }
 
-static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap)
+static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
 {
 	if (!pgmap->ops || !pgmap->ops->page_free) {
 		WARN(1, "Missing page_free method\n");
@@ -36,13 +36,16 @@ static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgm
 
 	if (atomic_inc_return(&devmap_managed_enable) == 1)
 		static_branch_enable(&devmap_managed_key);
-	return devm_add_action_or_reset(dev, devmap_managed_enable_put, NULL);
+	return 0;
 }
 #else
-static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap)
+static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
 {
 	return -EINVAL;
 }
+static void devmap_managed_enable_put(void)
+{
+}
 #endif /* CONFIG_DEV_PAGEMAP_OPS */
 
 static void pgmap_array_delete(struct resource *res)
@@ -129,6 +132,7 @@ static void devm_memremap_pages_release(void *data)
 	untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
 	pgmap_array_delete(res);
 	WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
+	devmap_managed_enable_put();
 }
 
 static void dev_pagemap_percpu_release(struct percpu_ref *ref)
@@ -218,7 +222,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 	}
 
 	if (need_devmap_managed) {
-		error = devmap_managed_enable_get(dev, pgmap);
+		error = devmap_managed_enable_get(pgmap);
 		if (error)
 			return ERR_PTR(error);
 	}
@@ -327,6 +331,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
  err_array:
 	dev_pagemap_kill(pgmap);
 	dev_pagemap_cleanup(pgmap);
+	devmap_managed_enable_put();
 	return ERR_PTR(error);
 }
 EXPORT_SYMBOL_GPL(devm_memremap_pages);
-- 
2.20.1

[PATCH 4/4] memremap: provide a not device managed memremap_pages

[Christoph Hellwig]

The kvmppc ultravisor code wants a device private memory pool that is
system wide and not attached to a device.  Instead of faking up one
provide a low-level memremap_pages for it.  Note that this function is
not exported, and doesn't have a cleanup routine associated with it to
discourage use from more driver like users.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/memremap.h |  2 +
 mm/memremap.c            | 84 +++++++++++++++++++++++++---------------
 2 files changed, 54 insertions(+), 32 deletions(-)

diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 8f0013e18e14..fb2a0bd826b9 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -123,6 +123,8 @@ static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
 }
 
 #ifdef CONFIG_ZONE_DEVICE
+void *memremap_pages(struct dev_pagemap *pgmap, int nid);
+void memunmap_pages(struct dev_pagemap *pgmap);
 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
diff --git a/mm/memremap.c b/mm/memremap.c
index 4e11da4ecab9..9e163fe367ae 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -102,9 +102,8 @@ static void dev_pagemap_cleanup(struct dev_pagemap *pgmap)
 		pgmap->ref = NULL;
 }
 
-static void devm_memremap_pages_release(void *data)
+void memunmap_pages(struct dev_pagemap *pgmap)
 {
-	struct dev_pagemap *pgmap = data;
 	struct resource *res = &pgmap->res;
 	unsigned long pfn;
 	int nid;
@@ -134,6 +133,12 @@ static void devm_memremap_pages_release(void *data)
 	WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
 	devmap_managed_enable_put();
 }
+EXPORT_SYMBOL_GPL(memunmap_pages);
+
+static void devm_memremap_pages_release(void *data)
+{
+	memunmap_pages(data);
+}
 
 static void dev_pagemap_percpu_release(struct percpu_ref *ref)
 {
@@ -143,27 +148,12 @@ static void dev_pagemap_percpu_release(struct percpu_ref *ref)
 	complete(&pgmap->done);
 }
 
-/**
- * devm_memremap_pages - remap and provide memmap backing for the given resource
- * @dev: hosting device for @res
- * @pgmap: pointer to a struct dev_pagemap
- *
- * Notes:
- * 1/ At a minimum the res and type members of @pgmap must be initialized
- *    by the caller before passing it to this function
- *
- * 2/ The altmap field may optionally be initialized, in which case
- *    PGMAP_ALTMAP_VALID must be set in pgmap->flags.
- *
- * 3/ The ref field may optionally be provided, in which pgmap->ref must be
- *    'live' on entry and will be killed and reaped at
- *    devm_memremap_pages_release() time, or if this routine fails.
- *
- * 4/ res is expected to be a host memory range that could feasibly be
- *    treated as a "System RAM" range, i.e. not a device mmio range, but
- *    this is not enforced.
+/*
+ * Not device managed version of dev_memremap_pages, undone by
+ * memunmap_pages().  Please use dev_memremap_pages if you have a struct
+ * device available.
  */
-void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
+void *memremap_pages(struct dev_pagemap *pgmap, int nid)
 {
 	struct resource *res = &pgmap->res;
 	struct dev_pagemap *conflict_pgmap;
@@ -174,7 +164,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 		.altmap = pgmap_altmap(pgmap),
 	};
 	pgprot_t pgprot = PAGE_KERNEL;
-	int error, nid, is_ram;
+	int error, is_ram;
 	bool need_devmap_managed = true;
 
 	switch (pgmap->type) {
@@ -229,7 +219,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 
 	conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->start), NULL);
 	if (conflict_pgmap) {
-		dev_WARN(dev, "Conflicting mapping in same section\n");
+		WARN(1, "Conflicting mapping in same section\n");
 		put_dev_pagemap(conflict_pgmap);
 		error = -ENOMEM;
 		goto err_array;
@@ -237,7 +227,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 
 	conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->end), NULL);
 	if (conflict_pgmap) {
-		dev_WARN(dev, "Conflicting mapping in same section\n");
+		WARN(1, "Conflicting mapping in same section\n");
 		put_dev_pagemap(conflict_pgmap);
 		error = -ENOMEM;
 		goto err_array;
@@ -258,7 +248,6 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 	if (error)
 		goto err_array;
 
-	nid = dev_to_node(dev);
 	if (nid < 0)
 		nid = numa_mem_id();
 
@@ -314,12 +303,6 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 				PHYS_PFN(res->start),
 				PHYS_PFN(resource_size(res)), pgmap);
 	percpu_ref_get_many(pgmap->ref, pfn_end(pgmap) - pfn_first(pgmap));
-
-	error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
-			pgmap);
-	if (error)
-		return ERR_PTR(error);
-
 	return __va(res->start);
 
  err_add_memory:
@@ -334,6 +317,43 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 	devmap_managed_enable_put();
 	return ERR_PTR(error);
 }
+EXPORT_SYMBOL_GPL(memremap_pages);
+
+/**
+ * devm_memremap_pages - remap and provide memmap backing for the given resource
+ * @dev: hosting device for @res
+ * @pgmap: pointer to a struct dev_pagemap
+ *
+ * Notes:
+ * 1/ At a minimum the res and type members of @pgmap must be initialized
+ *    by the caller before passing it to this function
+ *
+ * 2/ The altmap field may optionally be initialized, in which case
+ *    PGMAP_ALTMAP_VALID must be set in pgmap->flags.
+ *
+ * 3/ The ref field may optionally be provided, in which pgmap->ref must be
+ *    'live' on entry and will be killed and reaped at
+ *    devm_memremap_pages_release() time, or if this routine fails.
+ *
+ * 4/ res is expected to be a host memory range that could feasibly be
+ *    treated as a "System RAM" range, i.e. not a device mmio range, but
+ *    this is not enforced.
+ */
+void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
+{
+	int error;
+	void *ret;
+
+	ret = memremap_pages(pgmap, dev_to_node(dev));
+	if (IS_ERR(ret))
+		return ret;
+
+	error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
+			pgmap);
+	if (error)
+		return ERR_PTR(error);
+	return ret;
+}
 EXPORT_SYMBOL_GPL(devm_memremap_pages);
 
 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap)
-- 
2.20.1

Re: [PATCH 4/4] memremap: provide a not device managed memremap_pages

[Andrew Morton]

On Fri, 16 Aug 2019 08:54:34 +0200 Christoph Hellwig <hch@lst.de> wrote:

> The kvmppc ultravisor code wants a device private memory pool that is
> system wide and not attached to a device.  Instead of faking up one
> provide a low-level memremap_pages for it.  Note that this function is
> not exported, and doesn't have a cleanup routine associated with it to
> discourage use from more driver like users.

Confused. Which function is "not exported"?

> +EXPORT_SYMBOL_GPL(memunmap_pages);
> +EXPORT_SYMBOL_GPL(memremap_pages);
>  EXPORT_SYMBOL_GPL(devm_memremap_pages);

Re: [PATCH 4/4] memremap: provide a not device managed memremap_pages

[Christoph Hellwig]

On Fri, Aug 16, 2019 at 02:00:57PM -0700, Andrew Morton wrote:
> On Fri, 16 Aug 2019 08:54:34 +0200 Christoph Hellwig <hch@lst.de> wrote:
> 
> > The kvmppc ultravisor code wants a device private memory pool that is
> > system wide and not attached to a device.  Instead of faking up one
> > provide a low-level memremap_pages for it.  Note that this function is
> > not exported, and doesn't have a cleanup routine associated with it to
> > discourage use from more driver like users.
> 
> Confused. Which function is "not exported"?

Leftover from v1 and dropped now.

Re: add a not device managed memremap_pages v2

[Bharata B Rao]

On Fri, Aug 16, 2019 at 08:54:30AM +0200, Christoph Hellwig wrote:
> Hi Dan and Jason,
> 
> Bharata has been working on secure page management for kvmppc guests,
> and one I thing I noticed is that he had to fake up a struct device
> just so that it could be passed to the devm_memremap_pages
> instrastructure for device private memory.
> 
> This series adds non-device managed versions of the
> devm_request_free_mem_region and devm_memremap_pages functions for
> his use case.

Tested this series with my patches that add secure page management
for kvmppc guests. These patches along with migrate_vma-cleanup
series are good-to-have to support secure guests on ultravisor enabled
POWER platforms.

Regards,
Bharata.

Re: add a not device managed memremap_pages v2

[Jason Gunthorpe]

On Fri, Aug 16, 2019 at 08:54:30AM +0200, Christoph Hellwig wrote:
> Hi Dan and Jason,
> 
> Bharata has been working on secure page management for kvmppc guests,
> and one I thing I noticed is that he had to fake up a struct device
> just so that it could be passed to the devm_memremap_pages
> instrastructure for device private memory.
> 
> This series adds non-device managed versions of the
> devm_request_free_mem_region and devm_memremap_pages functions for
> his use case.
> 
> Changes since v1:
>  - don't overload devm_request_free_mem_region
>  - export the memremap_pages and munmap_pages as kvmppc can be a module

What tree do we want this to go through? Dan are you running a pgmap
tree still? Do we know of any conflicts?

Thanks,
Jason

Re: add a not device managed memremap_pages v2

[Christoph Hellwig]

> > Changes since v1:
> >  - don't overload devm_request_free_mem_region
> >  - export the memremap_pages and munmap_pages as kvmppc can be a module
> 
> What tree do we want this to go through? Dan are you running a pgmap
> tree still? Do we know of any conflicts?

The last changes in this area went through the hmm tree.  There are
now known conflicts, and the kvmppc drivers that needs this already
has a dependency on the hmm tree for the migrate_vma_* changes.

Re: add a not device managed memremap_pages v2

[Jason Gunthorpe]

On Fri, Aug 16, 2019 at 02:36:07PM +0200, Christoph Hellwig wrote:
> > > Changes since v1:
> > >  - don't overload devm_request_free_mem_region
> > >  - export the memremap_pages and munmap_pages as kvmppc can be a module
> > 
> > What tree do we want this to go through? Dan are you running a pgmap
> > tree still? Do we know of any conflicts?
> 
> The last changes in this area went through the hmm tree.  There are
> now known conflicts, and the kvmppc drivers that needs this already
> has a dependency on the hmm tree for the migrate_vma_* changes.

OK by me, Dan can you ack or review? Thanks

Jason

Re: add a not device managed memremap_pages v2

[Ira Weiny]

On Fri, Aug 16, 2019 at 08:54:30AM +0200, Christoph Hellwig wrote:
> Hi Dan and Jason,
> 
> Bharata has been working on secure page management for kvmppc guests,
> and one I thing I noticed is that he had to fake up a struct device
> just so that it could be passed to the devm_memremap_pages
> instrastructure for device private memory.
> 
> This series adds non-device managed versions of the
> devm_request_free_mem_region and devm_memremap_pages functions for
> his use case.
> 
> Changes since v1:
>  - don't overload devm_request_free_mem_region
>  - export the memremap_pages and munmap_pages as kvmppc can be a module

Except for the questions from Andrew this does not look to change anything so:

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

> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@lists.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm

add a not device managed memremap_pages v3

[Christoph Hellwig]

Hi Dan and Jason,

Bharata has been working on secure page management for kvmppc guests,
and one I thing I noticed is that he had to fake up a struct device
just so that it could be passed to the devm_memremap_pages
instrastructure for device private memory.

This series adds non-device managed versions of the
devm_request_free_mem_region and devm_memremap_pages functions for
his use case.

Changes since v2:
 - improved changelogs that the the v2 changes into account

Changes since v1:
 - don't overload devm_request_free_mem_region
 - export the memremap_pages and munmap_pages as kvmppc can be a module

[PATCH 3/4] memremap: don't use a separate devm action for devmap_managed_enable_get

[Christoph Hellwig]

Just clean up for early failures and then piggy back on
devm_memremap_pages_release.  This helps with a pending not device
managed version of devm_memremap_pages.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
---
 kernel/memremap.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 600a14cbe663..09a087ca30ff 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -21,13 +21,13 @@ DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
 EXPORT_SYMBOL(devmap_managed_key);
 static atomic_t devmap_managed_enable;
 
-static void devmap_managed_enable_put(void *data)
+static void devmap_managed_enable_put(void)
 {
 	if (atomic_dec_and_test(&devmap_managed_enable))
 		static_branch_disable(&devmap_managed_key);
 }
 
-static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap)
+static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
 {
 	if (!pgmap->ops || !pgmap->ops->page_free) {
 		WARN(1, "Missing page_free method\n");
@@ -36,13 +36,16 @@ static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgm
 
 	if (atomic_inc_return(&devmap_managed_enable) == 1)
 		static_branch_enable(&devmap_managed_key);
-	return devm_add_action_or_reset(dev, devmap_managed_enable_put, NULL);
+	return 0;
 }
 #else
-static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap)
+static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
 {
 	return -EINVAL;
 }
+static void devmap_managed_enable_put(void)
+{
+}
 #endif /* CONFIG_DEV_PAGEMAP_OPS */
 
 static void pgmap_array_delete(struct resource *res)
@@ -123,6 +126,7 @@ static void devm_memremap_pages_release(void *data)
 	untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
 	pgmap_array_delete(res);
 	WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
+	devmap_managed_enable_put();
 }
 
 static void dev_pagemap_percpu_release(struct percpu_ref *ref)
@@ -212,7 +216,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 	}
 
 	if (need_devmap_managed) {
-		error = devmap_managed_enable_get(dev, pgmap);
+		error = devmap_managed_enable_get(pgmap);
 		if (error)
 			return ERR_PTR(error);
 	}
@@ -321,6 +325,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
  err_array:
 	dev_pagemap_kill(pgmap);
 	dev_pagemap_cleanup(pgmap);
+	devmap_managed_enable_put();
 	return ERR_PTR(error);
 }
 EXPORT_SYMBOL_GPL(devm_memremap_pages);
-- 
2.20.1

Re: [PATCH 3/4] memremap: don't use a separate devm action for devmap_managed_enable_get

[Dan Williams]

On Sun, Aug 18, 2019 at 2:12 AM Christoph Hellwig <hch@lst.de> wrote:
>
> Just clean up for early failures and then piggy back on
> devm_memremap_pages_release.  This helps with a pending not device
> managed version of devm_memremap_pages.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Ira Weiny <ira.weiny@intel.com>

Looks good,

Reviewed-by: Dan Williams <dan.j.williams@intel.com>