![Dan Williams](/assets/img/avatar_default.png)
Logan noticed that devm_memremap_pages_release() kills the percpu_ref
drops all the page references that were acquired at init and then
immediately proceeds to unplug, arch_remove_memory(), the backing pages
for the pagemap. If for some reason device shutdown actually collides
with a busy / elevated-ref-count page then arch_remove_memory() should
be deferred until after that reference is dropped.
As it stands the "wait for last page ref drop" happens *after*
devm_memremap_pages_release() returns, which is obviously too late and
can lead to crashes.
Fix this situation by assigning the responsibility to wait for the
percpu_ref to go idle to devm_memremap_pages() with a new ->cleanup()
callback. Implement the new cleanup callback for all
devm_memremap_pages() users: pmem, devdax, hmm, and p2pdma.
Link: http://lkml.kernel.org/r/155727339156.292046.5432007428235387859.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: 41e94a8513
("add devm_memremap_pages")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
861 lines
22 KiB
C
861 lines
22 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* PCI Peer 2 Peer DMA support.
|
|
*
|
|
* Copyright (c) 2016-2018, Logan Gunthorpe
|
|
* Copyright (c) 2016-2017, Microsemi Corporation
|
|
* Copyright (c) 2017, Christoph Hellwig
|
|
* Copyright (c) 2018, Eideticom Inc.
|
|
*/
|
|
|
|
#define pr_fmt(fmt) "pci-p2pdma: " fmt
|
|
#include <linux/ctype.h>
|
|
#include <linux/pci-p2pdma.h>
|
|
#include <linux/module.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/genalloc.h>
|
|
#include <linux/memremap.h>
|
|
#include <linux/percpu-refcount.h>
|
|
#include <linux/random.h>
|
|
#include <linux/seq_buf.h>
|
|
|
|
struct pci_p2pdma {
|
|
struct gen_pool *pool;
|
|
bool p2pmem_published;
|
|
};
|
|
|
|
struct p2pdma_pagemap {
|
|
struct dev_pagemap pgmap;
|
|
struct percpu_ref ref;
|
|
struct completion ref_done;
|
|
};
|
|
|
|
static ssize_t size_show(struct device *dev, struct device_attribute *attr,
|
|
char *buf)
|
|
{
|
|
struct pci_dev *pdev = to_pci_dev(dev);
|
|
size_t size = 0;
|
|
|
|
if (pdev->p2pdma->pool)
|
|
size = gen_pool_size(pdev->p2pdma->pool);
|
|
|
|
return snprintf(buf, PAGE_SIZE, "%zd\n", size);
|
|
}
|
|
static DEVICE_ATTR_RO(size);
|
|
|
|
static ssize_t available_show(struct device *dev, struct device_attribute *attr,
|
|
char *buf)
|
|
{
|
|
struct pci_dev *pdev = to_pci_dev(dev);
|
|
size_t avail = 0;
|
|
|
|
if (pdev->p2pdma->pool)
|
|
avail = gen_pool_avail(pdev->p2pdma->pool);
|
|
|
|
return snprintf(buf, PAGE_SIZE, "%zd\n", avail);
|
|
}
|
|
static DEVICE_ATTR_RO(available);
|
|
|
|
static ssize_t published_show(struct device *dev, struct device_attribute *attr,
|
|
char *buf)
|
|
{
|
|
struct pci_dev *pdev = to_pci_dev(dev);
|
|
|
|
return snprintf(buf, PAGE_SIZE, "%d\n",
|
|
pdev->p2pdma->p2pmem_published);
|
|
}
|
|
static DEVICE_ATTR_RO(published);
|
|
|
|
static struct attribute *p2pmem_attrs[] = {
|
|
&dev_attr_size.attr,
|
|
&dev_attr_available.attr,
|
|
&dev_attr_published.attr,
|
|
NULL,
|
|
};
|
|
|
|
static const struct attribute_group p2pmem_group = {
|
|
.attrs = p2pmem_attrs,
|
|
.name = "p2pmem",
|
|
};
|
|
|
|
static struct p2pdma_pagemap *to_p2p_pgmap(struct percpu_ref *ref)
|
|
{
|
|
return container_of(ref, struct p2pdma_pagemap, ref);
|
|
}
|
|
|
|
static void pci_p2pdma_percpu_release(struct percpu_ref *ref)
|
|
{
|
|
struct p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(ref);
|
|
|
|
complete(&p2p_pgmap->ref_done);
|
|
}
|
|
|
|
static void pci_p2pdma_percpu_kill(struct percpu_ref *ref)
|
|
{
|
|
percpu_ref_kill(ref);
|
|
}
|
|
|
|
static void pci_p2pdma_percpu_cleanup(struct percpu_ref *ref)
|
|
{
|
|
struct p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(ref);
|
|
|
|
wait_for_completion(&p2p_pgmap->ref_done);
|
|
percpu_ref_exit(&p2p_pgmap->ref);
|
|
}
|
|
|
|
static void pci_p2pdma_release(void *data)
|
|
{
|
|
struct pci_dev *pdev = data;
|
|
struct pci_p2pdma *p2pdma = pdev->p2pdma;
|
|
|
|
if (!p2pdma)
|
|
return;
|
|
|
|
/* Flush and disable pci_alloc_p2p_mem() */
|
|
pdev->p2pdma = NULL;
|
|
synchronize_rcu();
|
|
|
|
gen_pool_destroy(p2pdma->pool);
|
|
sysfs_remove_group(&pdev->dev.kobj, &p2pmem_group);
|
|
}
|
|
|
|
static int pci_p2pdma_setup(struct pci_dev *pdev)
|
|
{
|
|
int error = -ENOMEM;
|
|
struct pci_p2pdma *p2p;
|
|
|
|
p2p = devm_kzalloc(&pdev->dev, sizeof(*p2p), GFP_KERNEL);
|
|
if (!p2p)
|
|
return -ENOMEM;
|
|
|
|
p2p->pool = gen_pool_create(PAGE_SHIFT, dev_to_node(&pdev->dev));
|
|
if (!p2p->pool)
|
|
goto out;
|
|
|
|
error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_release, pdev);
|
|
if (error)
|
|
goto out_pool_destroy;
|
|
|
|
pdev->p2pdma = p2p;
|
|
|
|
error = sysfs_create_group(&pdev->dev.kobj, &p2pmem_group);
|
|
if (error)
|
|
goto out_pool_destroy;
|
|
|
|
return 0;
|
|
|
|
out_pool_destroy:
|
|
pdev->p2pdma = NULL;
|
|
gen_pool_destroy(p2p->pool);
|
|
out:
|
|
devm_kfree(&pdev->dev, p2p);
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* pci_p2pdma_add_resource - add memory for use as p2p memory
|
|
* @pdev: the device to add the memory to
|
|
* @bar: PCI BAR to add
|
|
* @size: size of the memory to add, may be zero to use the whole BAR
|
|
* @offset: offset into the PCI BAR
|
|
*
|
|
* The memory will be given ZONE_DEVICE struct pages so that it may
|
|
* be used with any DMA request.
|
|
*/
|
|
int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
|
|
u64 offset)
|
|
{
|
|
struct p2pdma_pagemap *p2p_pgmap;
|
|
struct dev_pagemap *pgmap;
|
|
void *addr;
|
|
int error;
|
|
|
|
if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
|
|
return -EINVAL;
|
|
|
|
if (offset >= pci_resource_len(pdev, bar))
|
|
return -EINVAL;
|
|
|
|
if (!size)
|
|
size = pci_resource_len(pdev, bar) - offset;
|
|
|
|
if (size + offset > pci_resource_len(pdev, bar))
|
|
return -EINVAL;
|
|
|
|
if (!pdev->p2pdma) {
|
|
error = pci_p2pdma_setup(pdev);
|
|
if (error)
|
|
return error;
|
|
}
|
|
|
|
p2p_pgmap = devm_kzalloc(&pdev->dev, sizeof(*p2p_pgmap), GFP_KERNEL);
|
|
if (!p2p_pgmap)
|
|
return -ENOMEM;
|
|
|
|
init_completion(&p2p_pgmap->ref_done);
|
|
error = percpu_ref_init(&p2p_pgmap->ref,
|
|
pci_p2pdma_percpu_release, 0, GFP_KERNEL);
|
|
if (error)
|
|
goto pgmap_free;
|
|
|
|
pgmap = &p2p_pgmap->pgmap;
|
|
|
|
pgmap->res.start = pci_resource_start(pdev, bar) + offset;
|
|
pgmap->res.end = pgmap->res.start + size - 1;
|
|
pgmap->res.flags = pci_resource_flags(pdev, bar);
|
|
pgmap->ref = &p2p_pgmap->ref;
|
|
pgmap->type = MEMORY_DEVICE_PCI_P2PDMA;
|
|
pgmap->pci_p2pdma_bus_offset = pci_bus_address(pdev, bar) -
|
|
pci_resource_start(pdev, bar);
|
|
pgmap->kill = pci_p2pdma_percpu_kill;
|
|
pgmap->cleanup = pci_p2pdma_percpu_cleanup;
|
|
|
|
addr = devm_memremap_pages(&pdev->dev, pgmap);
|
|
if (IS_ERR(addr)) {
|
|
error = PTR_ERR(addr);
|
|
goto pgmap_free;
|
|
}
|
|
|
|
error = gen_pool_add_owner(pdev->p2pdma->pool, (unsigned long)addr,
|
|
pci_bus_address(pdev, bar) + offset,
|
|
resource_size(&pgmap->res), dev_to_node(&pdev->dev),
|
|
&p2p_pgmap->ref);
|
|
if (error)
|
|
goto pages_free;
|
|
|
|
pci_info(pdev, "added peer-to-peer DMA memory %pR\n",
|
|
&pgmap->res);
|
|
|
|
return 0;
|
|
|
|
pages_free:
|
|
devm_memunmap_pages(&pdev->dev, pgmap);
|
|
pgmap_free:
|
|
devm_kfree(&pdev->dev, p2p_pgmap);
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_p2pdma_add_resource);
|
|
|
|
/*
|
|
* Note this function returns the parent PCI device with a
|
|
* reference taken. It is the caller's responsibily to drop
|
|
* the reference.
|
|
*/
|
|
static struct pci_dev *find_parent_pci_dev(struct device *dev)
|
|
{
|
|
struct device *parent;
|
|
|
|
dev = get_device(dev);
|
|
|
|
while (dev) {
|
|
if (dev_is_pci(dev))
|
|
return to_pci_dev(dev);
|
|
|
|
parent = get_device(dev->parent);
|
|
put_device(dev);
|
|
dev = parent;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Check if a PCI bridge has its ACS redirection bits set to redirect P2P
|
|
* TLPs upstream via ACS. Returns 1 if the packets will be redirected
|
|
* upstream, 0 otherwise.
|
|
*/
|
|
static int pci_bridge_has_acs_redir(struct pci_dev *pdev)
|
|
{
|
|
int pos;
|
|
u16 ctrl;
|
|
|
|
pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_ACS);
|
|
if (!pos)
|
|
return 0;
|
|
|
|
pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl);
|
|
|
|
if (ctrl & (PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_EC))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void seq_buf_print_bus_devfn(struct seq_buf *buf, struct pci_dev *pdev)
|
|
{
|
|
if (!buf)
|
|
return;
|
|
|
|
seq_buf_printf(buf, "%s;", pci_name(pdev));
|
|
}
|
|
|
|
/*
|
|
* If we can't find a common upstream bridge take a look at the root
|
|
* complex and compare it to a whitelist of known good hardware.
|
|
*/
|
|
static bool root_complex_whitelist(struct pci_dev *dev)
|
|
{
|
|
struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
|
|
struct pci_dev *root = pci_get_slot(host->bus, PCI_DEVFN(0, 0));
|
|
unsigned short vendor, device;
|
|
|
|
if (!root)
|
|
return false;
|
|
|
|
vendor = root->vendor;
|
|
device = root->device;
|
|
pci_dev_put(root);
|
|
|
|
/* AMD ZEN host bridges can do peer to peer */
|
|
if (vendor == PCI_VENDOR_ID_AMD && device == 0x1450)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Find the distance through the nearest common upstream bridge between
|
|
* two PCI devices.
|
|
*
|
|
* If the two devices are the same device then 0 will be returned.
|
|
*
|
|
* If there are two virtual functions of the same device behind the same
|
|
* bridge port then 2 will be returned (one step down to the PCIe switch,
|
|
* then one step back to the same device).
|
|
*
|
|
* In the case where two devices are connected to the same PCIe switch, the
|
|
* value 4 will be returned. This corresponds to the following PCI tree:
|
|
*
|
|
* -+ Root Port
|
|
* \+ Switch Upstream Port
|
|
* +-+ Switch Downstream Port
|
|
* + \- Device A
|
|
* \-+ Switch Downstream Port
|
|
* \- Device B
|
|
*
|
|
* The distance is 4 because we traverse from Device A through the downstream
|
|
* port of the switch, to the common upstream port, back up to the second
|
|
* downstream port and then to Device B.
|
|
*
|
|
* Any two devices that don't have a common upstream bridge will return -1.
|
|
* In this way devices on separate PCIe root ports will be rejected, which
|
|
* is what we want for peer-to-peer seeing each PCIe root port defines a
|
|
* separate hierarchy domain and there's no way to determine whether the root
|
|
* complex supports forwarding between them.
|
|
*
|
|
* In the case where two devices are connected to different PCIe switches,
|
|
* this function will still return a positive distance as long as both
|
|
* switches eventually have a common upstream bridge. Note this covers
|
|
* the case of using multiple PCIe switches to achieve a desired level of
|
|
* fan-out from a root port. The exact distance will be a function of the
|
|
* number of switches between Device A and Device B.
|
|
*
|
|
* If a bridge which has any ACS redirection bits set is in the path
|
|
* then this functions will return -2. This is so we reject any
|
|
* cases where the TLPs are forwarded up into the root complex.
|
|
* In this case, a list of all infringing bridge addresses will be
|
|
* populated in acs_list (assuming it's non-null) for printk purposes.
|
|
*/
|
|
static int upstream_bridge_distance(struct pci_dev *provider,
|
|
struct pci_dev *client,
|
|
struct seq_buf *acs_list)
|
|
{
|
|
struct pci_dev *a = provider, *b = client, *bb;
|
|
int dist_a = 0;
|
|
int dist_b = 0;
|
|
int acs_cnt = 0;
|
|
|
|
/*
|
|
* Note, we don't need to take references to devices returned by
|
|
* pci_upstream_bridge() seeing we hold a reference to a child
|
|
* device which will already hold a reference to the upstream bridge.
|
|
*/
|
|
|
|
while (a) {
|
|
dist_b = 0;
|
|
|
|
if (pci_bridge_has_acs_redir(a)) {
|
|
seq_buf_print_bus_devfn(acs_list, a);
|
|
acs_cnt++;
|
|
}
|
|
|
|
bb = b;
|
|
|
|
while (bb) {
|
|
if (a == bb)
|
|
goto check_b_path_acs;
|
|
|
|
bb = pci_upstream_bridge(bb);
|
|
dist_b++;
|
|
}
|
|
|
|
a = pci_upstream_bridge(a);
|
|
dist_a++;
|
|
}
|
|
|
|
/*
|
|
* Allow the connection if both devices are on a whitelisted root
|
|
* complex, but add an arbitary large value to the distance.
|
|
*/
|
|
if (root_complex_whitelist(provider) &&
|
|
root_complex_whitelist(client))
|
|
return 0x1000 + dist_a + dist_b;
|
|
|
|
return -1;
|
|
|
|
check_b_path_acs:
|
|
bb = b;
|
|
|
|
while (bb) {
|
|
if (a == bb)
|
|
break;
|
|
|
|
if (pci_bridge_has_acs_redir(bb)) {
|
|
seq_buf_print_bus_devfn(acs_list, bb);
|
|
acs_cnt++;
|
|
}
|
|
|
|
bb = pci_upstream_bridge(bb);
|
|
}
|
|
|
|
if (acs_cnt)
|
|
return -2;
|
|
|
|
return dist_a + dist_b;
|
|
}
|
|
|
|
static int upstream_bridge_distance_warn(struct pci_dev *provider,
|
|
struct pci_dev *client)
|
|
{
|
|
struct seq_buf acs_list;
|
|
int ret;
|
|
|
|
seq_buf_init(&acs_list, kmalloc(PAGE_SIZE, GFP_KERNEL), PAGE_SIZE);
|
|
if (!acs_list.buffer)
|
|
return -ENOMEM;
|
|
|
|
ret = upstream_bridge_distance(provider, client, &acs_list);
|
|
if (ret == -2) {
|
|
pci_warn(client, "cannot be used for peer-to-peer DMA as ACS redirect is set between the client and provider (%s)\n",
|
|
pci_name(provider));
|
|
/* Drop final semicolon */
|
|
acs_list.buffer[acs_list.len-1] = 0;
|
|
pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n",
|
|
acs_list.buffer);
|
|
|
|
} else if (ret < 0) {
|
|
pci_warn(client, "cannot be used for peer-to-peer DMA as the client and provider (%s) do not share an upstream bridge\n",
|
|
pci_name(provider));
|
|
}
|
|
|
|
kfree(acs_list.buffer);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* pci_p2pdma_distance_many - Determive the cumulative distance between
|
|
* a p2pdma provider and the clients in use.
|
|
* @provider: p2pdma provider to check against the client list
|
|
* @clients: array of devices to check (NULL-terminated)
|
|
* @num_clients: number of clients in the array
|
|
* @verbose: if true, print warnings for devices when we return -1
|
|
*
|
|
* Returns -1 if any of the clients are not compatible (behind the same
|
|
* root port as the provider), otherwise returns a positive number where
|
|
* a lower number is the preferable choice. (If there's one client
|
|
* that's the same as the provider it will return 0, which is best choice).
|
|
*
|
|
* For now, "compatible" means the provider and the clients are all behind
|
|
* the same PCI root port. This cuts out cases that may work but is safest
|
|
* for the user. Future work can expand this to white-list root complexes that
|
|
* can safely forward between each ports.
|
|
*/
|
|
int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients,
|
|
int num_clients, bool verbose)
|
|
{
|
|
bool not_supported = false;
|
|
struct pci_dev *pci_client;
|
|
int distance = 0;
|
|
int i, ret;
|
|
|
|
if (num_clients == 0)
|
|
return -1;
|
|
|
|
for (i = 0; i < num_clients; i++) {
|
|
pci_client = find_parent_pci_dev(clients[i]);
|
|
if (!pci_client) {
|
|
if (verbose)
|
|
dev_warn(clients[i],
|
|
"cannot be used for peer-to-peer DMA as it is not a PCI device\n");
|
|
return -1;
|
|
}
|
|
|
|
if (verbose)
|
|
ret = upstream_bridge_distance_warn(provider,
|
|
pci_client);
|
|
else
|
|
ret = upstream_bridge_distance(provider, pci_client,
|
|
NULL);
|
|
|
|
pci_dev_put(pci_client);
|
|
|
|
if (ret < 0)
|
|
not_supported = true;
|
|
|
|
if (not_supported && !verbose)
|
|
break;
|
|
|
|
distance += ret;
|
|
}
|
|
|
|
if (not_supported)
|
|
return -1;
|
|
|
|
return distance;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_p2pdma_distance_many);
|
|
|
|
/**
|
|
* pci_has_p2pmem - check if a given PCI device has published any p2pmem
|
|
* @pdev: PCI device to check
|
|
*/
|
|
bool pci_has_p2pmem(struct pci_dev *pdev)
|
|
{
|
|
return pdev->p2pdma && pdev->p2pdma->p2pmem_published;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_has_p2pmem);
|
|
|
|
/**
|
|
* pci_p2pmem_find - find a peer-to-peer DMA memory device compatible with
|
|
* the specified list of clients and shortest distance (as determined
|
|
* by pci_p2pmem_dma())
|
|
* @clients: array of devices to check (NULL-terminated)
|
|
* @num_clients: number of client devices in the list
|
|
*
|
|
* If multiple devices are behind the same switch, the one "closest" to the
|
|
* client devices in use will be chosen first. (So if one of the providers is
|
|
* the same as one of the clients, that provider will be used ahead of any
|
|
* other providers that are unrelated). If multiple providers are an equal
|
|
* distance away, one will be chosen at random.
|
|
*
|
|
* Returns a pointer to the PCI device with a reference taken (use pci_dev_put
|
|
* to return the reference) or NULL if no compatible device is found. The
|
|
* found provider will also be assigned to the client list.
|
|
*/
|
|
struct pci_dev *pci_p2pmem_find_many(struct device **clients, int num_clients)
|
|
{
|
|
struct pci_dev *pdev = NULL;
|
|
int distance;
|
|
int closest_distance = INT_MAX;
|
|
struct pci_dev **closest_pdevs;
|
|
int dev_cnt = 0;
|
|
const int max_devs = PAGE_SIZE / sizeof(*closest_pdevs);
|
|
int i;
|
|
|
|
closest_pdevs = kmalloc(PAGE_SIZE, GFP_KERNEL);
|
|
if (!closest_pdevs)
|
|
return NULL;
|
|
|
|
while ((pdev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, pdev))) {
|
|
if (!pci_has_p2pmem(pdev))
|
|
continue;
|
|
|
|
distance = pci_p2pdma_distance_many(pdev, clients,
|
|
num_clients, false);
|
|
if (distance < 0 || distance > closest_distance)
|
|
continue;
|
|
|
|
if (distance == closest_distance && dev_cnt >= max_devs)
|
|
continue;
|
|
|
|
if (distance < closest_distance) {
|
|
for (i = 0; i < dev_cnt; i++)
|
|
pci_dev_put(closest_pdevs[i]);
|
|
|
|
dev_cnt = 0;
|
|
closest_distance = distance;
|
|
}
|
|
|
|
closest_pdevs[dev_cnt++] = pci_dev_get(pdev);
|
|
}
|
|
|
|
if (dev_cnt)
|
|
pdev = pci_dev_get(closest_pdevs[prandom_u32_max(dev_cnt)]);
|
|
|
|
for (i = 0; i < dev_cnt; i++)
|
|
pci_dev_put(closest_pdevs[i]);
|
|
|
|
kfree(closest_pdevs);
|
|
return pdev;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_p2pmem_find_many);
|
|
|
|
/**
|
|
* pci_alloc_p2p_mem - allocate peer-to-peer DMA memory
|
|
* @pdev: the device to allocate memory from
|
|
* @size: number of bytes to allocate
|
|
*
|
|
* Returns the allocated memory or NULL on error.
|
|
*/
|
|
void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size)
|
|
{
|
|
void *ret = NULL;
|
|
struct percpu_ref *ref;
|
|
|
|
/*
|
|
* Pairs with synchronize_rcu() in pci_p2pdma_release() to
|
|
* ensure pdev->p2pdma is non-NULL for the duration of the
|
|
* read-lock.
|
|
*/
|
|
rcu_read_lock();
|
|
if (unlikely(!pdev->p2pdma))
|
|
goto out;
|
|
|
|
ret = (void *)gen_pool_alloc_owner(pdev->p2pdma->pool, size,
|
|
(void **) &ref);
|
|
if (!ret)
|
|
goto out;
|
|
|
|
if (unlikely(!percpu_ref_tryget_live(ref))) {
|
|
gen_pool_free(pdev->p2pdma->pool, (unsigned long) ret, size);
|
|
ret = NULL;
|
|
goto out;
|
|
}
|
|
out:
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_alloc_p2pmem);
|
|
|
|
/**
|
|
* pci_free_p2pmem - free peer-to-peer DMA memory
|
|
* @pdev: the device the memory was allocated from
|
|
* @addr: address of the memory that was allocated
|
|
* @size: number of bytes that were allocated
|
|
*/
|
|
void pci_free_p2pmem(struct pci_dev *pdev, void *addr, size_t size)
|
|
{
|
|
struct percpu_ref *ref;
|
|
|
|
gen_pool_free_owner(pdev->p2pdma->pool, (uintptr_t)addr, size,
|
|
(void **) &ref);
|
|
percpu_ref_put(ref);
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_free_p2pmem);
|
|
|
|
/**
|
|
* pci_virt_to_bus - return the PCI bus address for a given virtual
|
|
* address obtained with pci_alloc_p2pmem()
|
|
* @pdev: the device the memory was allocated from
|
|
* @addr: address of the memory that was allocated
|
|
*/
|
|
pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr)
|
|
{
|
|
if (!addr)
|
|
return 0;
|
|
if (!pdev->p2pdma)
|
|
return 0;
|
|
|
|
/*
|
|
* Note: when we added the memory to the pool we used the PCI
|
|
* bus address as the physical address. So gen_pool_virt_to_phys()
|
|
* actually returns the bus address despite the misleading name.
|
|
*/
|
|
return gen_pool_virt_to_phys(pdev->p2pdma->pool, (unsigned long)addr);
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_p2pmem_virt_to_bus);
|
|
|
|
/**
|
|
* pci_p2pmem_alloc_sgl - allocate peer-to-peer DMA memory in a scatterlist
|
|
* @pdev: the device to allocate memory from
|
|
* @nents: the number of SG entries in the list
|
|
* @length: number of bytes to allocate
|
|
*
|
|
* Return: %NULL on error or &struct scatterlist pointer and @nents on success
|
|
*/
|
|
struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev,
|
|
unsigned int *nents, u32 length)
|
|
{
|
|
struct scatterlist *sg;
|
|
void *addr;
|
|
|
|
sg = kzalloc(sizeof(*sg), GFP_KERNEL);
|
|
if (!sg)
|
|
return NULL;
|
|
|
|
sg_init_table(sg, 1);
|
|
|
|
addr = pci_alloc_p2pmem(pdev, length);
|
|
if (!addr)
|
|
goto out_free_sg;
|
|
|
|
sg_set_buf(sg, addr, length);
|
|
*nents = 1;
|
|
return sg;
|
|
|
|
out_free_sg:
|
|
kfree(sg);
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_p2pmem_alloc_sgl);
|
|
|
|
/**
|
|
* pci_p2pmem_free_sgl - free a scatterlist allocated by pci_p2pmem_alloc_sgl()
|
|
* @pdev: the device to allocate memory from
|
|
* @sgl: the allocated scatterlist
|
|
*/
|
|
void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl)
|
|
{
|
|
struct scatterlist *sg;
|
|
int count;
|
|
|
|
for_each_sg(sgl, sg, INT_MAX, count) {
|
|
if (!sg)
|
|
break;
|
|
|
|
pci_free_p2pmem(pdev, sg_virt(sg), sg->length);
|
|
}
|
|
kfree(sgl);
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_p2pmem_free_sgl);
|
|
|
|
/**
|
|
* pci_p2pmem_publish - publish the peer-to-peer DMA memory for use by
|
|
* other devices with pci_p2pmem_find()
|
|
* @pdev: the device with peer-to-peer DMA memory to publish
|
|
* @publish: set to true to publish the memory, false to unpublish it
|
|
*
|
|
* Published memory can be used by other PCI device drivers for
|
|
* peer-2-peer DMA operations. Non-published memory is reserved for
|
|
* exclusive use of the device driver that registers the peer-to-peer
|
|
* memory.
|
|
*/
|
|
void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
|
|
{
|
|
if (pdev->p2pdma)
|
|
pdev->p2pdma->p2pmem_published = publish;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
|
|
|
|
/**
|
|
* pci_p2pdma_map_sg - map a PCI peer-to-peer scatterlist for DMA
|
|
* @dev: device doing the DMA request
|
|
* @sg: scatter list to map
|
|
* @nents: elements in the scatterlist
|
|
* @dir: DMA direction
|
|
*
|
|
* Scatterlists mapped with this function should not be unmapped in any way.
|
|
*
|
|
* Returns the number of SG entries mapped or 0 on error.
|
|
*/
|
|
int pci_p2pdma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
|
|
enum dma_data_direction dir)
|
|
{
|
|
struct dev_pagemap *pgmap;
|
|
struct scatterlist *s;
|
|
phys_addr_t paddr;
|
|
int i;
|
|
|
|
/*
|
|
* p2pdma mappings are not compatible with devices that use
|
|
* dma_virt_ops. If the upper layers do the right thing
|
|
* this should never happen because it will be prevented
|
|
* by the check in pci_p2pdma_add_client()
|
|
*/
|
|
if (WARN_ON_ONCE(IS_ENABLED(CONFIG_DMA_VIRT_OPS) &&
|
|
dev->dma_ops == &dma_virt_ops))
|
|
return 0;
|
|
|
|
for_each_sg(sg, s, nents, i) {
|
|
pgmap = sg_page(s)->pgmap;
|
|
paddr = sg_phys(s);
|
|
|
|
s->dma_address = paddr - pgmap->pci_p2pdma_bus_offset;
|
|
sg_dma_len(s) = s->length;
|
|
}
|
|
|
|
return nents;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_p2pdma_map_sg);
|
|
|
|
/**
|
|
* pci_p2pdma_enable_store - parse a configfs/sysfs attribute store
|
|
* to enable p2pdma
|
|
* @page: contents of the value to be stored
|
|
* @p2p_dev: returns the PCI device that was selected to be used
|
|
* (if one was specified in the stored value)
|
|
* @use_p2pdma: returns whether to enable p2pdma or not
|
|
*
|
|
* Parses an attribute value to decide whether to enable p2pdma.
|
|
* The value can select a PCI device (using its full BDF device
|
|
* name) or a boolean (in any format strtobool() accepts). A false
|
|
* value disables p2pdma, a true value expects the caller
|
|
* to automatically find a compatible device and specifying a PCI device
|
|
* expects the caller to use the specific provider.
|
|
*
|
|
* pci_p2pdma_enable_show() should be used as the show operation for
|
|
* the attribute.
|
|
*
|
|
* Returns 0 on success
|
|
*/
|
|
int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev,
|
|
bool *use_p2pdma)
|
|
{
|
|
struct device *dev;
|
|
|
|
dev = bus_find_device_by_name(&pci_bus_type, NULL, page);
|
|
if (dev) {
|
|
*use_p2pdma = true;
|
|
*p2p_dev = to_pci_dev(dev);
|
|
|
|
if (!pci_has_p2pmem(*p2p_dev)) {
|
|
pci_err(*p2p_dev,
|
|
"PCI device has no peer-to-peer memory: %s\n",
|
|
page);
|
|
pci_dev_put(*p2p_dev);
|
|
return -ENODEV;
|
|
}
|
|
|
|
return 0;
|
|
} else if ((page[0] == '0' || page[0] == '1') && !iscntrl(page[1])) {
|
|
/*
|
|
* If the user enters a PCI device that doesn't exist
|
|
* like "0000:01:00.1", we don't want strtobool to think
|
|
* it's a '0' when it's clearly not what the user wanted.
|
|
* So we require 0's and 1's to be exactly one character.
|
|
*/
|
|
} else if (!strtobool(page, use_p2pdma)) {
|
|
return 0;
|
|
}
|
|
|
|
pr_err("No such PCI device: %.*s\n", (int)strcspn(page, "\n"), page);
|
|
return -ENODEV;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_p2pdma_enable_store);
|
|
|
|
/**
|
|
* pci_p2pdma_enable_show - show a configfs/sysfs attribute indicating
|
|
* whether p2pdma is enabled
|
|
* @page: contents of the stored value
|
|
* @p2p_dev: the selected p2p device (NULL if no device is selected)
|
|
* @use_p2pdma: whether p2pdma has been enabled
|
|
*
|
|
* Attributes that use pci_p2pdma_enable_store() should use this function
|
|
* to show the value of the attribute.
|
|
*
|
|
* Returns 0 on success
|
|
*/
|
|
ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev,
|
|
bool use_p2pdma)
|
|
{
|
|
if (!use_p2pdma)
|
|
return sprintf(page, "0\n");
|
|
|
|
if (!p2p_dev)
|
|
return sprintf(page, "1\n");
|
|
|
|
return sprintf(page, "%s\n", pci_name(p2p_dev));
|
|
}
|
|
EXPORT_SYMBOL_GPL(pci_p2pdma_enable_show);
|