linux/drivers/misc/cxl/api.c
Christophe Lombard 6dd2d23403 cxl: Keep track of mm struct associated with a context
The mm_struct corresponding to the current task is acquired each time
an interrupt is raised. So to simplify the code, we only get the
mm_struct when attaching an AFU context to the process.
The mm_count reference is increased to ensure that the mm_struct can't
be freed. The mm_struct will be released when the context is detached.
A reference on mm_users is not kept to avoid a circular dependency if
the process mmaps its cxl mmio and forget to unmap before exiting.
The field glpid (pid of the group leader associated with the pid), of
the structure cxl_context, is removed because it's no longer useful.

Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2017-04-13 23:34:29 +10:00

673 lines
15 KiB
C

/*
* Copyright 2014 IBM Corp.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <misc/cxl.h>
#include <linux/msi.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/sched/mm.h>
#include "cxl.h"
/*
* Since we want to track memory mappings to be able to force-unmap
* when the AFU is no longer reachable, we need an inode. For devices
* opened through the cxl user API, this is not a problem, but a
* userland process can also get a cxl fd through the cxl_get_fd()
* API, which is used by the cxlflash driver.
*
* Therefore we implement our own simple pseudo-filesystem and inode
* allocator. We don't use the anonymous inode, as we need the
* meta-data associated with it (address_space) and it is shared by
* other drivers/processes, so it could lead to cxl unmapping VMAs
* from random processes.
*/
#define CXL_PSEUDO_FS_MAGIC 0x1697697f
static int cxl_fs_cnt;
static struct vfsmount *cxl_vfs_mount;
static const struct dentry_operations cxl_fs_dops = {
.d_dname = simple_dname,
};
static struct dentry *cxl_fs_mount(struct file_system_type *fs_type, int flags,
const char *dev_name, void *data)
{
return mount_pseudo(fs_type, "cxl:", NULL, &cxl_fs_dops,
CXL_PSEUDO_FS_MAGIC);
}
static struct file_system_type cxl_fs_type = {
.name = "cxl",
.owner = THIS_MODULE,
.mount = cxl_fs_mount,
.kill_sb = kill_anon_super,
};
void cxl_release_mapping(struct cxl_context *ctx)
{
if (ctx->kernelapi && ctx->mapping)
simple_release_fs(&cxl_vfs_mount, &cxl_fs_cnt);
}
static struct file *cxl_getfile(const char *name,
const struct file_operations *fops,
void *priv, int flags)
{
struct qstr this;
struct path path;
struct file *file;
struct inode *inode = NULL;
int rc;
/* strongly inspired by anon_inode_getfile() */
if (fops->owner && !try_module_get(fops->owner))
return ERR_PTR(-ENOENT);
rc = simple_pin_fs(&cxl_fs_type, &cxl_vfs_mount, &cxl_fs_cnt);
if (rc < 0) {
pr_err("Cannot mount cxl pseudo filesystem: %d\n", rc);
file = ERR_PTR(rc);
goto err_module;
}
inode = alloc_anon_inode(cxl_vfs_mount->mnt_sb);
if (IS_ERR(inode)) {
file = ERR_CAST(inode);
goto err_fs;
}
file = ERR_PTR(-ENOMEM);
this.name = name;
this.len = strlen(name);
this.hash = 0;
path.dentry = d_alloc_pseudo(cxl_vfs_mount->mnt_sb, &this);
if (!path.dentry)
goto err_inode;
path.mnt = mntget(cxl_vfs_mount);
d_instantiate(path.dentry, inode);
file = alloc_file(&path, OPEN_FMODE(flags), fops);
if (IS_ERR(file))
goto err_dput;
file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
file->private_data = priv;
return file;
err_dput:
path_put(&path);
err_inode:
iput(inode);
err_fs:
simple_release_fs(&cxl_vfs_mount, &cxl_fs_cnt);
err_module:
module_put(fops->owner);
return file;
}
struct cxl_context *cxl_dev_context_init(struct pci_dev *dev)
{
struct cxl_afu *afu;
struct cxl_context *ctx;
int rc;
afu = cxl_pci_to_afu(dev);
if (IS_ERR(afu))
return ERR_CAST(afu);
ctx = cxl_context_alloc();
if (!ctx)
return ERR_PTR(-ENOMEM);
ctx->kernelapi = true;
/* Make it a slave context. We can promote it later? */
rc = cxl_context_init(ctx, afu, false);
if (rc)
goto err_ctx;
return ctx;
err_ctx:
kfree(ctx);
return ERR_PTR(rc);
}
EXPORT_SYMBOL_GPL(cxl_dev_context_init);
struct cxl_context *cxl_get_context(struct pci_dev *dev)
{
return dev->dev.archdata.cxl_ctx;
}
EXPORT_SYMBOL_GPL(cxl_get_context);
int cxl_release_context(struct cxl_context *ctx)
{
if (ctx->status >= STARTED)
return -EBUSY;
cxl_context_free(ctx);
return 0;
}
EXPORT_SYMBOL_GPL(cxl_release_context);
static irq_hw_number_t cxl_find_afu_irq(struct cxl_context *ctx, int num)
{
__u16 range;
int r;
for (r = 0; r < CXL_IRQ_RANGES; r++) {
range = ctx->irqs.range[r];
if (num < range) {
return ctx->irqs.offset[r] + num;
}
num -= range;
}
return 0;
}
int _cxl_next_msi_hwirq(struct pci_dev *pdev, struct cxl_context **ctx, int *afu_irq)
{
if (*ctx == NULL || *afu_irq == 0) {
*afu_irq = 1;
*ctx = cxl_get_context(pdev);
} else {
(*afu_irq)++;
if (*afu_irq > cxl_get_max_irqs_per_process(pdev)) {
*ctx = list_next_entry(*ctx, extra_irq_contexts);
*afu_irq = 1;
}
}
return cxl_find_afu_irq(*ctx, *afu_irq);
}
/* Exported via cxl_base */
int cxl_set_priv(struct cxl_context *ctx, void *priv)
{
if (!ctx)
return -EINVAL;
ctx->priv = priv;
return 0;
}
EXPORT_SYMBOL_GPL(cxl_set_priv);
void *cxl_get_priv(struct cxl_context *ctx)
{
if (!ctx)
return ERR_PTR(-EINVAL);
return ctx->priv;
}
EXPORT_SYMBOL_GPL(cxl_get_priv);
int cxl_allocate_afu_irqs(struct cxl_context *ctx, int num)
{
int res;
irq_hw_number_t hwirq;
if (num == 0)
num = ctx->afu->pp_irqs;
res = afu_allocate_irqs(ctx, num);
if (res)
return res;
if (!cpu_has_feature(CPU_FTR_HVMODE)) {
/* In a guest, the PSL interrupt is not multiplexed. It was
* allocated above, and we need to set its handler
*/
hwirq = cxl_find_afu_irq(ctx, 0);
if (hwirq)
cxl_map_irq(ctx->afu->adapter, hwirq, cxl_ops->psl_interrupt, ctx, "psl");
}
if (ctx->status == STARTED) {
if (cxl_ops->update_ivtes)
cxl_ops->update_ivtes(ctx);
else WARN(1, "BUG: cxl_allocate_afu_irqs must be called prior to starting the context on this platform\n");
}
return res;
}
EXPORT_SYMBOL_GPL(cxl_allocate_afu_irqs);
void cxl_free_afu_irqs(struct cxl_context *ctx)
{
irq_hw_number_t hwirq;
unsigned int virq;
if (!cpu_has_feature(CPU_FTR_HVMODE)) {
hwirq = cxl_find_afu_irq(ctx, 0);
if (hwirq) {
virq = irq_find_mapping(NULL, hwirq);
if (virq)
cxl_unmap_irq(virq, ctx);
}
}
afu_irq_name_free(ctx);
cxl_ops->release_irq_ranges(&ctx->irqs, ctx->afu->adapter);
}
EXPORT_SYMBOL_GPL(cxl_free_afu_irqs);
int cxl_map_afu_irq(struct cxl_context *ctx, int num,
irq_handler_t handler, void *cookie, char *name)
{
irq_hw_number_t hwirq;
/*
* Find interrupt we are to register.
*/
hwirq = cxl_find_afu_irq(ctx, num);
if (!hwirq)
return -ENOENT;
return cxl_map_irq(ctx->afu->adapter, hwirq, handler, cookie, name);
}
EXPORT_SYMBOL_GPL(cxl_map_afu_irq);
void cxl_unmap_afu_irq(struct cxl_context *ctx, int num, void *cookie)
{
irq_hw_number_t hwirq;
unsigned int virq;
hwirq = cxl_find_afu_irq(ctx, num);
if (!hwirq)
return;
virq = irq_find_mapping(NULL, hwirq);
if (virq)
cxl_unmap_irq(virq, cookie);
}
EXPORT_SYMBOL_GPL(cxl_unmap_afu_irq);
/*
* Start a context
* Code here similar to afu_ioctl_start_work().
*/
int cxl_start_context(struct cxl_context *ctx, u64 wed,
struct task_struct *task)
{
int rc = 0;
bool kernel = true;
pr_devel("%s: pe: %i\n", __func__, ctx->pe);
mutex_lock(&ctx->status_mutex);
if (ctx->status == STARTED)
goto out; /* already started */
/*
* Increment the mapped context count for adapter. This also checks
* if adapter_context_lock is taken.
*/
rc = cxl_adapter_context_get(ctx->afu->adapter);
if (rc)
goto out;
if (task) {
ctx->pid = get_task_pid(task, PIDTYPE_PID);
kernel = false;
ctx->real_mode = false;
/* acquire a reference to the task's mm */
ctx->mm = get_task_mm(current);
/* ensure this mm_struct can't be freed */
cxl_context_mm_count_get(ctx);
/* decrement the use count */
if (ctx->mm)
mmput(ctx->mm);
}
cxl_ctx_get();
if ((rc = cxl_ops->attach_process(ctx, kernel, wed, 0))) {
put_pid(ctx->pid);
ctx->pid = NULL;
cxl_adapter_context_put(ctx->afu->adapter);
cxl_ctx_put();
if (task)
cxl_context_mm_count_put(ctx);
goto out;
}
ctx->status = STARTED;
out:
mutex_unlock(&ctx->status_mutex);
return rc;
}
EXPORT_SYMBOL_GPL(cxl_start_context);
int cxl_process_element(struct cxl_context *ctx)
{
return ctx->external_pe;
}
EXPORT_SYMBOL_GPL(cxl_process_element);
/* Stop a context. Returns 0 on success, otherwise -Errno */
int cxl_stop_context(struct cxl_context *ctx)
{
return __detach_context(ctx);
}
EXPORT_SYMBOL_GPL(cxl_stop_context);
void cxl_set_master(struct cxl_context *ctx)
{
ctx->master = true;
}
EXPORT_SYMBOL_GPL(cxl_set_master);
int cxl_set_translation_mode(struct cxl_context *ctx, bool real_mode)
{
if (ctx->status == STARTED) {
/*
* We could potentially update the PE and issue an update LLCMD
* to support this, but it doesn't seem to have a good use case
* since it's trivial to just create a second kernel context
* with different translation modes, so until someone convinces
* me otherwise:
*/
return -EBUSY;
}
ctx->real_mode = real_mode;
return 0;
}
EXPORT_SYMBOL_GPL(cxl_set_translation_mode);
/* wrappers around afu_* file ops which are EXPORTED */
int cxl_fd_open(struct inode *inode, struct file *file)
{
return afu_open(inode, file);
}
EXPORT_SYMBOL_GPL(cxl_fd_open);
int cxl_fd_release(struct inode *inode, struct file *file)
{
return afu_release(inode, file);
}
EXPORT_SYMBOL_GPL(cxl_fd_release);
long cxl_fd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
return afu_ioctl(file, cmd, arg);
}
EXPORT_SYMBOL_GPL(cxl_fd_ioctl);
int cxl_fd_mmap(struct file *file, struct vm_area_struct *vm)
{
return afu_mmap(file, vm);
}
EXPORT_SYMBOL_GPL(cxl_fd_mmap);
unsigned int cxl_fd_poll(struct file *file, struct poll_table_struct *poll)
{
return afu_poll(file, poll);
}
EXPORT_SYMBOL_GPL(cxl_fd_poll);
ssize_t cxl_fd_read(struct file *file, char __user *buf, size_t count,
loff_t *off)
{
return afu_read(file, buf, count, off);
}
EXPORT_SYMBOL_GPL(cxl_fd_read);
#define PATCH_FOPS(NAME) if (!fops->NAME) fops->NAME = afu_fops.NAME
/* Get a struct file and fd for a context and attach the ops */
struct file *cxl_get_fd(struct cxl_context *ctx, struct file_operations *fops,
int *fd)
{
struct file *file;
int rc, flags, fdtmp;
char *name = NULL;
/* only allow one per context */
if (ctx->mapping)
return ERR_PTR(-EEXIST);
flags = O_RDWR | O_CLOEXEC;
/* This code is similar to anon_inode_getfd() */
rc = get_unused_fd_flags(flags);
if (rc < 0)
return ERR_PTR(rc);
fdtmp = rc;
/*
* Patch the file ops. Needs to be careful that this is rentrant safe.
*/
if (fops) {
PATCH_FOPS(open);
PATCH_FOPS(poll);
PATCH_FOPS(read);
PATCH_FOPS(release);
PATCH_FOPS(unlocked_ioctl);
PATCH_FOPS(compat_ioctl);
PATCH_FOPS(mmap);
} else /* use default ops */
fops = (struct file_operations *)&afu_fops;
name = kasprintf(GFP_KERNEL, "cxl:%d", ctx->pe);
file = cxl_getfile(name, fops, ctx, flags);
kfree(name);
if (IS_ERR(file))
goto err_fd;
cxl_context_set_mapping(ctx, file->f_mapping);
*fd = fdtmp;
return file;
err_fd:
put_unused_fd(fdtmp);
return NULL;
}
EXPORT_SYMBOL_GPL(cxl_get_fd);
struct cxl_context *cxl_fops_get_context(struct file *file)
{
return file->private_data;
}
EXPORT_SYMBOL_GPL(cxl_fops_get_context);
void cxl_set_driver_ops(struct cxl_context *ctx,
struct cxl_afu_driver_ops *ops)
{
WARN_ON(!ops->fetch_event || !ops->event_delivered);
atomic_set(&ctx->afu_driver_events, 0);
ctx->afu_driver_ops = ops;
}
EXPORT_SYMBOL_GPL(cxl_set_driver_ops);
void cxl_context_events_pending(struct cxl_context *ctx,
unsigned int new_events)
{
atomic_add(new_events, &ctx->afu_driver_events);
wake_up_all(&ctx->wq);
}
EXPORT_SYMBOL_GPL(cxl_context_events_pending);
int cxl_start_work(struct cxl_context *ctx,
struct cxl_ioctl_start_work *work)
{
int rc;
/* code taken from afu_ioctl_start_work */
if (!(work->flags & CXL_START_WORK_NUM_IRQS))
work->num_interrupts = ctx->afu->pp_irqs;
else if ((work->num_interrupts < ctx->afu->pp_irqs) ||
(work->num_interrupts > ctx->afu->irqs_max)) {
return -EINVAL;
}
rc = afu_register_irqs(ctx, work->num_interrupts);
if (rc)
return rc;
rc = cxl_start_context(ctx, work->work_element_descriptor, current);
if (rc < 0) {
afu_release_irqs(ctx, ctx);
return rc;
}
return 0;
}
EXPORT_SYMBOL_GPL(cxl_start_work);
void __iomem *cxl_psa_map(struct cxl_context *ctx)
{
if (ctx->status != STARTED)
return NULL;
pr_devel("%s: psn_phys%llx size:%llx\n",
__func__, ctx->psn_phys, ctx->psn_size);
return ioremap(ctx->psn_phys, ctx->psn_size);
}
EXPORT_SYMBOL_GPL(cxl_psa_map);
void cxl_psa_unmap(void __iomem *addr)
{
iounmap(addr);
}
EXPORT_SYMBOL_GPL(cxl_psa_unmap);
int cxl_afu_reset(struct cxl_context *ctx)
{
struct cxl_afu *afu = ctx->afu;
int rc;
rc = cxl_ops->afu_reset(afu);
if (rc)
return rc;
return cxl_ops->afu_check_and_enable(afu);
}
EXPORT_SYMBOL_GPL(cxl_afu_reset);
void cxl_perst_reloads_same_image(struct cxl_afu *afu,
bool perst_reloads_same_image)
{
afu->adapter->perst_same_image = perst_reloads_same_image;
}
EXPORT_SYMBOL_GPL(cxl_perst_reloads_same_image);
ssize_t cxl_read_adapter_vpd(struct pci_dev *dev, void *buf, size_t count)
{
struct cxl_afu *afu = cxl_pci_to_afu(dev);
if (IS_ERR(afu))
return -ENODEV;
return cxl_ops->read_adapter_vpd(afu->adapter, buf, count);
}
EXPORT_SYMBOL_GPL(cxl_read_adapter_vpd);
int cxl_set_max_irqs_per_process(struct pci_dev *dev, int irqs)
{
struct cxl_afu *afu = cxl_pci_to_afu(dev);
if (IS_ERR(afu))
return -ENODEV;
if (irqs > afu->adapter->user_irqs)
return -EINVAL;
/* Limit user_irqs to prevent the user increasing this via sysfs */
afu->adapter->user_irqs = irqs;
afu->irqs_max = irqs;
return 0;
}
EXPORT_SYMBOL_GPL(cxl_set_max_irqs_per_process);
int cxl_get_max_irqs_per_process(struct pci_dev *dev)
{
struct cxl_afu *afu = cxl_pci_to_afu(dev);
if (IS_ERR(afu))
return -ENODEV;
return afu->irqs_max;
}
EXPORT_SYMBOL_GPL(cxl_get_max_irqs_per_process);
/*
* This is a special interrupt allocation routine called from the PHB's MSI
* setup function. When capi interrupts are allocated in this manner they must
* still be associated with a running context, but since the MSI APIs have no
* way to specify this we use the default context associated with the device.
*
* The Mellanox CX4 has a hardware limitation that restricts the maximum AFU
* interrupt number, so in order to overcome this their driver informs us of
* the restriction by setting the maximum interrupts per context, and we
* allocate additional contexts as necessary so that we can keep the AFU
* interrupt number within the supported range.
*/
int _cxl_cx4_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
{
struct cxl_context *ctx, *new_ctx, *default_ctx;
int remaining;
int rc;
ctx = default_ctx = cxl_get_context(pdev);
if (WARN_ON(!default_ctx))
return -ENODEV;
remaining = nvec;
while (remaining > 0) {
rc = cxl_allocate_afu_irqs(ctx, min(remaining, ctx->afu->irqs_max));
if (rc) {
pr_warn("%s: Failed to find enough free MSIs\n", pci_name(pdev));
return rc;
}
remaining -= ctx->afu->irqs_max;
if (ctx != default_ctx && default_ctx->status == STARTED) {
WARN_ON(cxl_start_context(ctx,
be64_to_cpu(default_ctx->elem->common.wed),
NULL));
}
if (remaining > 0) {
new_ctx = cxl_dev_context_init(pdev);
if (IS_ERR(new_ctx)) {
pr_warn("%s: Failed to allocate enough contexts for MSIs\n", pci_name(pdev));
return -ENOSPC;
}
list_add(&new_ctx->extra_irq_contexts, &ctx->extra_irq_contexts);
ctx = new_ctx;
}
}
return 0;
}
/* Exported via cxl_base */
void _cxl_cx4_teardown_msi_irqs(struct pci_dev *pdev)
{
struct cxl_context *ctx, *pos, *tmp;
ctx = cxl_get_context(pdev);
if (WARN_ON(!ctx))
return;
cxl_free_afu_irqs(ctx);
list_for_each_entry_safe(pos, tmp, &ctx->extra_irq_contexts, extra_irq_contexts) {
cxl_stop_context(pos);
cxl_free_afu_irqs(pos);
list_del(&pos->extra_irq_contexts);
cxl_release_context(pos);
}
}
/* Exported via cxl_base */