Re: [RFC PATCH 1/2] xen/unpopulated-alloc: Introduce helpers for DMA allocations
From: Oleksandr
Date: Wed Jun 08 2022 - 14:12:35 EST
On 04.06.22 00:52, Stefano Stabellini wrote:
Hello Stefano
Thank you for having a look and sorry for the late response.
On Tue, 17 May 2022, Oleksandr Tyshchenko wrote:
From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
Add ability to allocate unpopulated DMAable (contiguous) pages
suitable for grant mapping into. This is going to be used by gnttab
code (see gnttab_dma_alloc_pages()).
TODO: There is a code duplication in fill_dma_pool(). Also pool
oparations likely need to be protected by the lock.
Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
---
drivers/xen/unpopulated-alloc.c | 167 ++++++++++++++++++++++++++++++++++++++++
include/xen/xen.h | 15 ++++
2 files changed, 182 insertions(+)
diff --git a/drivers/xen/unpopulated-alloc.c b/drivers/xen/unpopulated-alloc.c
index a39f2d3..bca0198 100644
--- a/drivers/xen/unpopulated-alloc.c
+++ b/drivers/xen/unpopulated-alloc.c
@@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/errno.h>
+#include <linux/genalloc.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/mm.h>
@@ -16,6 +17,8 @@ static DEFINE_MUTEX(list_lock);
static struct page *page_list;
static unsigned int list_count;
+static struct gen_pool *dma_pool;
+
static struct resource *target_resource;
/*
@@ -230,6 +233,161 @@ void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
}
EXPORT_SYMBOL(xen_free_unpopulated_pages);
+static int fill_dma_pool(unsigned int nr_pages)
+{
I think we shouldn't need to add this function at all as we should be
able to reuse fill_list even for contiguous pages. fill_list could
always call gen_pool_add_virt before returning.
First of all, I agree that fill_dma_pool() has a lot in common with
fill_list(), so we indeed can avoid code duplication (this was mentioned
in TODO).
I am not quite sure regarding "to always call gen_pool_add_virt before
returning" (does this mean that the same pages will be in the
"page_list" and "dma_pool" simultaneously?),
but I completely agree that we can reuse fill_list() for contiguous
pages as well slightly updating it.
Please see below.
+ struct dev_pagemap *pgmap;
+ struct resource *res, *tmp_res = NULL;
+ void *vaddr;
+ unsigned int alloc_pages = round_up(nr_pages, PAGES_PER_SECTION);
+ struct range mhp_range;
+ int ret;
+
+ res = kzalloc(sizeof(*res), GFP_KERNEL);
+ if (!res)
+ return -ENOMEM;
+
+ res->name = "Xen DMA pool";
+ res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+
+ mhp_range = mhp_get_pluggable_range(true);
+
+ ret = allocate_resource(target_resource, res,
+ alloc_pages * PAGE_SIZE, mhp_range.start, mhp_range.end,
+ PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
+ if (ret < 0) {
+ pr_err("Cannot allocate new IOMEM resource\n");
+ goto err_resource;
+ }
+
+ /*
+ * Reserve the region previously allocated from Xen resource to avoid
+ * re-using it by someone else.
+ */
+ if (target_resource != &iomem_resource) {
+ tmp_res = kzalloc(sizeof(*tmp_res), GFP_KERNEL);
+ if (!res) {
+ ret = -ENOMEM;
+ goto err_insert;
+ }
+
+ tmp_res->name = res->name;
+ tmp_res->start = res->start;
+ tmp_res->end = res->end;
+ tmp_res->flags = res->flags;
+
+ ret = request_resource(&iomem_resource, tmp_res);
+ if (ret < 0) {
+ pr_err("Cannot request resource %pR (%d)\n", tmp_res, ret);
+ kfree(tmp_res);
+ goto err_insert;
+ }
+ }
+
+ pgmap = kzalloc(sizeof(*pgmap), GFP_KERNEL);
+ if (!pgmap) {
+ ret = -ENOMEM;
+ goto err_pgmap;
+ }
+
+ pgmap->type = MEMORY_DEVICE_GENERIC;
+ pgmap->range = (struct range) {
+ .start = res->start,
+ .end = res->end,
+ };
+ pgmap->nr_range = 1;
+ pgmap->owner = res;
+
+ vaddr = memremap_pages(pgmap, NUMA_NO_NODE);
+ if (IS_ERR(vaddr)) {
+ pr_err("Cannot remap memory range\n");
+ ret = PTR_ERR(vaddr);
+ goto err_memremap;
+ }
+
+ ret = gen_pool_add_virt(dma_pool, (unsigned long)vaddr, res->start,
+ alloc_pages * PAGE_SIZE, NUMA_NO_NODE);
+ if (ret)
+ goto err_pool;
+
+ return 0;
+
+err_pool:
+ memunmap_pages(pgmap);
+err_memremap:
+ kfree(pgmap);
+err_pgmap:
+ if (tmp_res) {
+ release_resource(tmp_res);
+ kfree(tmp_res);
+ }
+err_insert:
+ release_resource(res);
+err_resource:
+ kfree(res);
+ return ret;
+}
+
+/**
+ * xen_alloc_unpopulated_dma_pages - alloc unpopulated DMAable pages
+ * @dev: valid struct device pointer
+ * @nr_pages: Number of pages
+ * @pages: pages returned
+ * @return 0 on success, error otherwise
+ */
+int xen_alloc_unpopulated_dma_pages(struct device *dev, unsigned int nr_pages,
+ struct page **pages)
+{
+ void *vaddr;
+ bool filled = false;
+ unsigned int i;
+ int ret;
Also probably it might be better if xen_alloc_unpopulated_pages and
xen_alloc_unpopulated_dma_pages shared the implementation. Something
along these lines:
int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
{
return _xen_alloc_unpopulated_pages(nr_pages, pages, false);
}
int xen_alloc_unpopulated_dma_pages(struct device *dev, unsigned int nr_pages,
struct page **pages)
{
return _xen_alloc_unpopulated_pages(nr_pages, pages, true);
}
I think, this makes sense, although it depends on how the resulting
_xen_alloc_unpopulated_pages() will look like. I'd
s/_xen_alloc_unpopulated_pages/alloc_unpopulated_pages
Please see below.
static int _xen_alloc_unpopulated_pages(unsigned int nr_pages,
struct page **pages, bool contiguous)
{
unsigned int i;
int ret = 0;
if (contiguous && !xen_feature(XENFEAT_auto_translated_physmap))
return -EINVAL;
/*
* Fallback to default behavior if we do not have any suitable resource
* to allocate required region from and as the result we won't be able to
* construct pages.
*/
if (!target_resource) {
if (contiguous)
return -EINVAL;
return xen_alloc_ballooned_pages(nr_pages, pages);
}
mutex_lock(&list_lock);
if (list_count < nr_pages) {
ret = fill_list(nr_pages - list_count);
As I understand, this might not work if we need contiguous pages. The
check might not be precise as "list_count" is a number of available
pages in the list, which are not guaranteed to be contiguous, also the
amount of pages to be added to the pool here "nr_pages - list_count"
might not be enough to allocate contiguous region with "nr_pages" size.
if (ret)
goto out;
}
if (contiguous) {
vaddr = (void *)gen_pool_alloc(dma_pool, nr_pages * PAGE_SIZE);
for (i = 0; i < nr_pages; i++)
pages[i] = virt_to_page(vaddr + PAGE_SIZE * i);
} else {
for (i = 0; i < nr_pages; i++) {
struct page *pg = page_list;
BUG_ON(!pg);
page_list = pg->zone_device_data;
list_count--;
pages[i] = pg;
I think, if we keep the same pages in the "page_list" and "dma_pool"
simultaneously we will need to reflect that here, otherwise we might end
up reusing already allocated pages.
What I mean is if we allocate pages from "dma_pool" we will need to
remove them from the "page_list" as well and vice versa, so this might
add a complexity to the code. I or missed something?
According to the suggestions I see two options, both follow suggestion
where xen_alloc(free)_unpopulated_pages() and
xen_alloc(free)_unpopulated_dma_pages() share the implementation.
1. Keep "page_list" and "dma_pool" separately. So they don't share
pages. Like how it was implemented in current patch but with eliminating
both TODOs. This doesn't change behavior for all users of
xen_alloc_unpopulated_pages().
Below the diff for unpopulated-alloc.c. The patch is also available at:
https://github.com/otyshchenko1/linux/commit/1c629abc37478c108a5f4c37ae8076b766c4d5cc
diff --git a/drivers/xen/unpopulated-alloc.c
b/drivers/xen/unpopulated-alloc.c
index a39f2d3..c3a86c09 100644
--- a/drivers/xen/unpopulated-alloc.c
+++ b/drivers/xen/unpopulated-alloc.c
@@ -1,5 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
+#include <linux/dma-mapping.h>
#include <linux/errno.h>
+#include <linux/genalloc.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/mm.h>
@@ -16,6 +18,8 @@ static DEFINE_MUTEX(list_lock);
static struct page *page_list;
static unsigned int list_count;
+static struct gen_pool *dma_pool;
+
static struct resource *target_resource;
/*
@@ -31,7 +35,7 @@ int __weak __init arch_xen_unpopulated_init(struct
resource **res)
return 0;
}
-static int fill_list(unsigned int nr_pages)
+static int fill_list(unsigned int nr_pages, bool use_pool)
{
struct dev_pagemap *pgmap;
struct resource *res, *tmp_res = NULL;
@@ -125,12 +129,21 @@ static int fill_list(unsigned int nr_pages)
goto err_memremap;
}
- for (i = 0; i < alloc_pages; i++) {
- struct page *pg = virt_to_page(vaddr + PAGE_SIZE * i);
+ if (use_pool) {
+ ret = gen_pool_add_virt(dma_pool, (unsigned long)vaddr,
res->start,
+ alloc_pages * PAGE_SIZE, NUMA_NO_NODE);
+ if (ret) {
+ memunmap_pages(pgmap);
+ goto err_memremap;
+ }
+ } else {
+ for (i = 0; i < alloc_pages; i++) {
+ struct page *pg = virt_to_page(vaddr + PAGE_SIZE
* i);
- pg->zone_device_data = page_list;
- page_list = pg;
- list_count++;
+ pg->zone_device_data = page_list;
+ page_list = pg;
+ list_count++;
+ }
}
return 0;
@@ -149,13 +162,8 @@ static int fill_list(unsigned int nr_pages)
return ret;
}
-/**
- * xen_alloc_unpopulated_pages - alloc unpopulated pages
- * @nr_pages: Number of pages
- * @pages: pages returned
- * @return 0 on success, error otherwise
- */
-int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
+static int alloc_unpopulated_pages(unsigned int nr_pages, struct page
**pages,
+ bool contiguous)
{
unsigned int i;
int ret = 0;
@@ -165,71 +173,167 @@ int xen_alloc_unpopulated_pages(unsigned int
nr_pages, struct page **pages)
* to allocate required region from and as the result we won't
be able to
* construct pages.
*/
- if (!target_resource)
+ if (!target_resource) {
+ if (contiguous)
+ return -ENODEV;
+
return xen_alloc_ballooned_pages(nr_pages, pages);
+ }
mutex_lock(&list_lock);
- if (list_count < nr_pages) {
- ret = fill_list(nr_pages - list_count);
- if (ret)
- goto out;
- }
- for (i = 0; i < nr_pages; i++) {
- struct page *pg = page_list;
+ if (contiguous) {
+ void *vaddr;
+ bool filled = false;
+
+ while (!(vaddr = (void *)gen_pool_alloc(dma_pool,
nr_pages * PAGE_SIZE))) {
+ if (filled)
+ ret = -ENOMEM;
+ else {
+ ret = fill_list(nr_pages, true);
+ filled = true;
+ }
+ if (ret)
+ goto out;
+ }
- BUG_ON(!pg);
- page_list = pg->zone_device_data;
- list_count--;
- pages[i] = pg;
+ for (i = 0; i < nr_pages; i++) {
+ pages[i] = virt_to_page(vaddr + PAGE_SIZE * i);
#ifdef CONFIG_XEN_HAVE_PVMMU
- if (!xen_feature(XENFEAT_auto_translated_physmap)) {
- ret = xen_alloc_p2m_entry(page_to_pfn(pg));
- if (ret < 0) {
- unsigned int j;
-
- for (j = 0; j <= i; j++) {
- pages[j]->zone_device_data = page_list;
- page_list = pages[j];
- list_count++;
+ if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+ ret =
xen_alloc_p2m_entry(page_to_pfn(pages[i]));
+ if (ret < 0) {
+ /* XXX Do we need to zeroed
pages[i]? */
+ gen_pool_free(dma_pool,
(unsigned long)vaddr,
+ nr_pages *
PAGE_SIZE);
+ goto out;
}
- goto out;
}
+#endif
+ }
+ } else {
+ if (list_count < nr_pages) {
+ ret = fill_list(nr_pages - list_count, false);
+ if (ret)
+ goto out;
}
+
+ for (i = 0; i < nr_pages; i++) {
+ struct page *pg = page_list;
+
+ BUG_ON(!pg);
+ page_list = pg->zone_device_data;
+ list_count--;
+ pages[i] = pg;
+
+#ifdef CONFIG_XEN_HAVE_PVMMU
+ if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+ ret = xen_alloc_p2m_entry(page_to_pfn(pg));
+ if (ret < 0) {
+ unsigned int j;
+
+ for (j = 0; j <= i; j++) {
+ pages[j]->zone_device_data = page_list;
+ page_list = pages[j];
+ list_count++;
+ }
+ goto out;
+ }
+ }
#endif
+ }
}
out:
mutex_unlock(&list_lock);
return ret;
}
-EXPORT_SYMBOL(xen_alloc_unpopulated_pages);
-/**
- * xen_free_unpopulated_pages - return unpopulated pages
- * @nr_pages: Number of pages
- * @pages: pages to return
- */
-void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
+static void free_unpopulated_pages(unsigned int nr_pages, struct page
**pages,
+ bool contiguous)
{
- unsigned int i;
-
if (!target_resource) {
+ if (contiguous)
+ return;
+
xen_free_ballooned_pages(nr_pages, pages);
return;
}
mutex_lock(&list_lock);
- for (i = 0; i < nr_pages; i++) {
- pages[i]->zone_device_data = page_list;
- page_list = pages[i];
- list_count++;
+
+ /* XXX Do we need to check the range (gen_pool_has_addr)? */
+ if (contiguous)
+ gen_pool_free(dma_pool, (unsigned
long)page_to_virt(pages[0]),
+ nr_pages * PAGE_SIZE);
+ else {
+ unsigned int i;
+
+ for (i = 0; i < nr_pages; i++) {
+ pages[i]->zone_device_data = page_list;
+ page_list = pages[i];
+ list_count++;
+ }
}
+
mutex_unlock(&list_lock);
}
+
+/**
+ * xen_alloc_unpopulated_pages - alloc unpopulated pages
+ * @nr_pages: Number of pages
+ * @pages: pages returned
+ * @return 0 on success, error otherwise
+ */
+int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
+{
+ return alloc_unpopulated_pages(nr_pages, pages, false);
+}
+EXPORT_SYMBOL(xen_alloc_unpopulated_pages);
+
+/**
+ * xen_free_unpopulated_pages - return unpopulated pages
+ * @nr_pages: Number of pages
+ * @pages: pages to return
+ */
+void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
+{
+ free_unpopulated_pages(nr_pages, pages, false);
+}
EXPORT_SYMBOL(xen_free_unpopulated_pages);
+/**
+ * xen_alloc_unpopulated_dma_pages - alloc unpopulated DMAable pages
+ * @dev: valid struct device pointer
+ * @nr_pages: Number of pages
+ * @pages: pages returned
+ * @return 0 on success, error otherwise
+ */
+int xen_alloc_unpopulated_dma_pages(struct device *dev, unsigned int
nr_pages,
+ struct page **pages)
+{
+ /* XXX Handle devices which support 64-bit DMA address only for
now */
+ if (dma_get_mask(dev) != DMA_BIT_MASK(64))
+ return -EINVAL;
+
+ return alloc_unpopulated_pages(nr_pages, pages, true);
+}
+EXPORT_SYMBOL(xen_alloc_unpopulated_dma_pages);
+
+/**
+ * xen_free_unpopulated_dma_pages - return unpopulated DMAable pages
+ * @dev: valid struct device pointer
+ * @nr_pages: Number of pages
+ * @pages: pages to return
+ */
+void xen_free_unpopulated_dma_pages(struct device *dev, unsigned int
nr_pages,
+ struct page **pages)
+{
+ free_unpopulated_pages(nr_pages, pages, true);
+}
+EXPORT_SYMBOL(xen_free_unpopulated_dma_pages);
+
static int __init unpopulated_init(void)
{
int ret;
@@ -237,9 +341,19 @@ static int __init unpopulated_init(void)
if (!xen_domain())
return -ENODEV;
+ dma_pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
+ if (!dma_pool) {
+ pr_err("xen:unpopulated: Cannot create DMA pool\n");
+ return -ENOMEM;
+ }
+
+ gen_pool_set_algo(dma_pool, gen_pool_best_fit, NULL);
+
ret = arch_xen_unpopulated_init(&target_resource);
if (ret) {
pr_err("xen:unpopulated: Cannot initialize target
resource\n");
+ gen_pool_destroy(dma_pool);
+ dma_pool = NULL;
target_resource = NULL;
}
[snip]
2. Drop the "page_list" entirely and use "dma_pool" for all (contiguous
and non-contiguous) allocations. After all, all pages are initially
contiguous in fill_list() as they are built from the resource. This
changes behavior for all users of xen_alloc_unpopulated_pages()
Below the diff for unpopulated-alloc.c. The patch is also available at:
https://github.com/otyshchenko1/linux/commit/7be569f113a4acbdc4bcb9b20cb3995b3151387a
diff --git a/drivers/xen/unpopulated-alloc.c
b/drivers/xen/unpopulated-alloc.c
index a39f2d3..ab5c7bd 100644
--- a/drivers/xen/unpopulated-alloc.c
+++ b/drivers/xen/unpopulated-alloc.c
@@ -1,5 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
+#include <linux/dma-mapping.h>
#include <linux/errno.h>
+#include <linux/genalloc.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/mm.h>
@@ -13,8 +15,8 @@
#include <xen/xen.h>
static DEFINE_MUTEX(list_lock);
-static struct page *page_list;
-static unsigned int list_count;
+
+static struct gen_pool *dma_pool;
static struct resource *target_resource;
@@ -36,7 +38,7 @@ static int fill_list(unsigned int nr_pages)
struct dev_pagemap *pgmap;
struct resource *res, *tmp_res = NULL;
void *vaddr;
- unsigned int i, alloc_pages = round_up(nr_pages, PAGES_PER_SECTION);
+ unsigned int alloc_pages = round_up(nr_pages, PAGES_PER_SECTION);
struct range mhp_range;
int ret;
@@ -106,6 +108,7 @@ static int fill_list(unsigned int nr_pages)
* conflict with any devices.
*/
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+ unsigned int i;
xen_pfn_t pfn = PFN_DOWN(res->start);
for (i = 0; i < alloc_pages; i++) {
@@ -125,16 +128,17 @@ static int fill_list(unsigned int nr_pages)
goto err_memremap;
}
- for (i = 0; i < alloc_pages; i++) {
- struct page *pg = virt_to_page(vaddr + PAGE_SIZE * i);
-
- pg->zone_device_data = page_list;
- page_list = pg;
- list_count++;
+ ret = gen_pool_add_virt(dma_pool, (unsigned long)vaddr, res->start,
+ alloc_pages * PAGE_SIZE, NUMA_NO_NODE);
+ if (ret) {
+ pr_err("Cannot add memory range to the pool\n");
+ goto err_pool;
}
return 0;
+err_pool:
+ memunmap_pages(pgmap);
err_memremap:
kfree(pgmap);
err_pgmap:
@@ -149,51 +153,49 @@ static int fill_list(unsigned int nr_pages)
return ret;
}
-/**
- * xen_alloc_unpopulated_pages - alloc unpopulated pages
- * @nr_pages: Number of pages
- * @pages: pages returned
- * @return 0 on success, error otherwise
- */
-int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
+static int alloc_unpopulated_pages(unsigned int nr_pages, struct page
**pages,
+ bool contiguous)
{
unsigned int i;
int ret = 0;
+ void *vaddr;
+ bool filled = false;
/*
* Fallback to default behavior if we do not have any suitable
resource
* to allocate required region from and as the result we won't
be able to
* construct pages.
*/
- if (!target_resource)
+ if (!target_resource) {
+ if (contiguous)
+ return -ENODEV;
+
return xen_alloc_ballooned_pages(nr_pages, pages);
+ }
mutex_lock(&list_lock);
- if (list_count < nr_pages) {
- ret = fill_list(nr_pages - list_count);
+
+ while (!(vaddr = (void *)gen_pool_alloc(dma_pool, nr_pages *
PAGE_SIZE))) {
+ if (filled)
+ ret = -ENOMEM;
+ else {
+ ret = fill_list(nr_pages);
+ filled = true;
+ }
if (ret)
goto out;
}
for (i = 0; i < nr_pages; i++) {
- struct page *pg = page_list;
-
- BUG_ON(!pg);
- page_list = pg->zone_device_data;
- list_count--;
- pages[i] = pg;
+ pages[i] = virt_to_page(vaddr + PAGE_SIZE * i);
#ifdef CONFIG_XEN_HAVE_PVMMU
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
- ret = xen_alloc_p2m_entry(page_to_pfn(pg));
+ ret = xen_alloc_p2m_entry(page_to_pfn(pages[i]));
if (ret < 0) {
- unsigned int j;
-
- for (j = 0; j <= i; j++) {
- pages[j]->zone_device_data = page_list;
- page_list = pages[j];
- list_count++;
- }
+ /* XXX Do we need to zeroed pages[i]? */
+ gen_pool_free(dma_pool, (unsigned
long)vaddr,
+ nr_pages * PAGE_SIZE);
goto out;
}
}
@@ -204,32 +206,89 @@ int xen_alloc_unpopulated_pages(unsigned int
nr_pages, struct page **pages)
mutex_unlock(&list_lock);
return ret;
}
-EXPORT_SYMBOL(xen_alloc_unpopulated_pages);
-/**
- * xen_free_unpopulated_pages - return unpopulated pages
- * @nr_pages: Number of pages
- * @pages: pages to return
- */
-void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
+static void free_unpopulated_pages(unsigned int nr_pages, struct page
**pages,
+ bool contiguous)
{
- unsigned int i;
-
if (!target_resource) {
+ if (contiguous)
+ return;
+
xen_free_ballooned_pages(nr_pages, pages);
return;
}
mutex_lock(&list_lock);
- for (i = 0; i < nr_pages; i++) {
- pages[i]->zone_device_data = page_list;
- page_list = pages[i];
- list_count++;
+
+ /* XXX Do we need to check the range (gen_pool_has_addr)? */
+ if (contiguous)
+ gen_pool_free(dma_pool, (unsigned
long)page_to_virt(pages[0]),
+ nr_pages * PAGE_SIZE);
+ else {
+ unsigned int i;
+
+ for (i = 0; i < nr_pages; i++)
+ gen_pool_free(dma_pool, (unsigned
long)page_to_virt(pages[i]),
+ PAGE_SIZE);
}
+
mutex_unlock(&list_lock);
}
+
+/**
+ * xen_alloc_unpopulated_pages - alloc unpopulated pages
+ * @nr_pages: Number of pages
+ * @pages: pages returned
+ * @return 0 on success, error otherwise
+ */
+int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
+{
+ return alloc_unpopulated_pages(nr_pages, pages, false);
+}
+EXPORT_SYMBOL(xen_alloc_unpopulated_pages);
+
+/**
+ * xen_free_unpopulated_pages - return unpopulated pages
+ * @nr_pages: Number of pages
+ * @pages: pages to return
+ */
+void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
+{
+ free_unpopulated_pages(nr_pages, pages, false);
+}
EXPORT_SYMBOL(xen_free_unpopulated_pages);
+/**
+ * xen_alloc_unpopulated_dma_pages - alloc unpopulated DMAable pages
+ * @dev: valid struct device pointer
+ * @nr_pages: Number of pages
+ * @pages: pages returned
+ * @return 0 on success, error otherwise
+ */
+int xen_alloc_unpopulated_dma_pages(struct device *dev, unsigned int
nr_pages,
+ struct page **pages)
+{
+ /* XXX Handle devices which support 64-bit DMA address only for
now */
+ if (dma_get_mask(dev) != DMA_BIT_MASK(64))
+ return -EINVAL;
+
+ return alloc_unpopulated_pages(nr_pages, pages, true);
+}
+EXPORT_SYMBOL(xen_alloc_unpopulated_dma_pages);
+
+/**
+ * xen_free_unpopulated_dma_pages - return unpopulated DMAable pages
+ * @dev: valid struct device pointer
+ * @nr_pages: Number of pages
+ * @pages: pages to return
+ */
+void xen_free_unpopulated_dma_pages(struct device *dev, unsigned int
nr_pages,
+ struct page **pages)
+{
+ free_unpopulated_pages(nr_pages, pages, true);
+}
+EXPORT_SYMBOL(xen_free_unpopulated_dma_pages);
+
static int __init unpopulated_init(void)
{
int ret;
@@ -237,9 +296,19 @@ static int __init unpopulated_init(void)
if (!xen_domain())
return -ENODEV;
+ dma_pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
+ if (!dma_pool) {
+ pr_err("xen:unpopulated: Cannot create DMA pool\n");
+ return -ENOMEM;
+ }
+
+ gen_pool_set_algo(dma_pool, gen_pool_best_fit, NULL);
+
ret = arch_xen_unpopulated_init(&target_resource);
if (ret) {
pr_err("xen:unpopulated: Cannot initialize target
resource\n");
+ gen_pool_destroy(dma_pool);
+ dma_pool = NULL;
target_resource = NULL;
}
[snip]
I think, regarding on the approach we would likely need to do some
renaming for fill_list, page_list, list_lock, etc.
Both options work in my Arm64 based environment, not sure regarding x86.
Or do we have another option here?
I would be happy to go any route. What do you think?
#ifdef CONFIG_XEN_HAVE_PVMMU
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
ret = xen_alloc_p2m_entry(page_to_pfn(pg));
if (ret < 0) {
unsigned int j;
for (j = 0; j <= i; j++) {
pages[j]->zone_device_data = page_list;
page_list = pages[j];
list_count++;
}
goto out;
}
}
#endif
}
}
out:
mutex_unlock(&list_lock);
return ret;
}
+ if (!dma_pool)
+ return -ENODEV;
+
+ /* XXX Handle devices which support 64-bit DMA address only for now */
+ if (dma_get_mask(dev) != DMA_BIT_MASK(64))
+ return -EINVAL;
+
+ while (!(vaddr = (void *)gen_pool_alloc(dma_pool, nr_pages * PAGE_SIZE))) {
+ if (filled)
+ return -ENOMEM;
+ else {
+ ret = fill_dma_pool(nr_pages);
+ if (ret)
+ return ret;
+
+ filled = true;
+ }
+ }
+
+ for (i = 0; i < nr_pages; i++)
+ pages[i] = virt_to_page(vaddr + PAGE_SIZE * i);
+
+ return 0;
+}
+EXPORT_SYMBOL(xen_alloc_unpopulated_dma_pages);
+
+/**
+ * xen_free_unpopulated_dma_pages - return unpopulated DMAable pages
+ * @dev: valid struct device pointer
+ * @nr_pages: Number of pages
+ * @pages: pages to return
+ */
+void xen_free_unpopulated_dma_pages(struct device *dev, unsigned int nr_pages,
+ struct page **pages)
+{
+ void *vaddr;
+
+ if (!dma_pool)
+ return;
+
+ vaddr = page_to_virt(pages[0]);
+
+ gen_pool_free(dma_pool, (unsigned long)vaddr, nr_pages * PAGE_SIZE);
+}
+EXPORT_SYMBOL(xen_free_unpopulated_dma_pages);
+
static int __init unpopulated_init(void)
{
int ret;
@@ -241,8 +399,17 @@ static int __init unpopulated_init(void)
if (ret) {
pr_err("xen:unpopulated: Cannot initialize target resource\n");
target_resource = NULL;
+ return ret;
}
+ dma_pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
+ if (!dma_pool) {
+ pr_err("xen:unpopulated: Cannot create DMA pool\n");
+ return -ENOMEM;
+ }
+
+ gen_pool_set_algo(dma_pool, gen_pool_best_fit, NULL);
+
return ret;
}
early_initcall(unpopulated_init);
diff --git a/include/xen/xen.h b/include/xen/xen.h
index a99bab8..a6a7a59 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -52,9 +52,15 @@ bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
extern u64 xen_saved_max_mem_size;
#endif
+struct device;
+
#ifdef CONFIG_XEN_UNPOPULATED_ALLOC
int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages);
void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages);
+int xen_alloc_unpopulated_dma_pages(struct device *dev, unsigned int nr_pages,
+ struct page **pages);
+void xen_free_unpopulated_dma_pages(struct device *dev, unsigned int nr_pages,
+ struct page **pages);
#include <linux/ioport.h>
int arch_xen_unpopulated_init(struct resource **res);
#else
@@ -69,6 +75,15 @@ static inline void xen_free_unpopulated_pages(unsigned int nr_pages,
{
xen_free_ballooned_pages(nr_pages, pages);
}
+static inline int xen_alloc_unpopulated_dma_pages(struct device *dev,
+ unsigned int nr_pages, struct page **pages)
+{
+ return -1;
+}
+static inline void xen_free_unpopulated_dma_pages(struct device *dev,
+ unsigned int nr_pages, struct page **pages)
+{
+}
#endif
Given that we have these stubs, maybe we don't need to #ifdef the so
much code in the next patch
ok, I will analyze
--
Regards,
Oleksandr Tyshchenko