Haren Myneni <haren@xxxxxxxxxxxxx> writes:
> On power9, userspace can send GZIP compression requests directly to NX
> once kernel establishes NX channel / window with VAS. This patch provides
> user space API which allows user space to establish channel using open
> VAS_TX_WIN_OPEN ioctl, mmap and close operations.
>
> Each window corresponds to file descriptor and application can open
> multiple windows. After the window is opened, VAS_TX_WIN_OPEN icoctl to
> open a window on specific VAS instance, mmap() system call to map
> the hardware address of engine's request queue into the application's
> virtual address space.
>
> Then the application can then submit one or more requests to the the
> engine by using the copy/paste instructions and pasting the CRBs to
> the virtual address (aka paste_address) returned by mmap().
>
> Only NX GZIP coprocessor type is supported right now and allow GZIP
> engine access via /dev/crypto/nx-gzip device node.
>
> Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Haren Myneni <haren@xxxxxxxxxxxxx>
> ---
> arch/powerpc/include/asm/vas.h | 11 ++
> arch/powerpc/platforms/powernv/Makefile | 2 +-
> arch/powerpc/platforms/powernv/vas-api.c | 290 ++++++++++++++++++++++++++++
> arch/powerpc/platforms/powernv/vas-window.c | 6 +-
> arch/powerpc/platforms/powernv/vas.h | 2 +
> 5 files changed, 307 insertions(+), 4 deletions(-)
> create mode 100644 arch/powerpc/platforms/powernv/vas-api.c
>
> diff --git a/arch/powerpc/include/asm/vas.h b/arch/powerpc/include/asm/vas.h
> index f93e6b0..e064953 100644
> --- a/arch/powerpc/include/asm/vas.h
> +++ b/arch/powerpc/include/asm/vas.h
> @@ -163,4 +163,15 @@ struct vas_window *vas_tx_win_open(int vasid, enum vas_cop_type cop,
> */
> int vas_paste_crb(struct vas_window *win, int offset, bool re);
>
> +/*
> + * Register / unregister coprocessor type to VAS API which will be exported
> + * to user space. Applications can use this API to open / close window
> + * which can be used to send / receive requests directly to cooprcessor.
> + *
> + * Only NX GZIP coprocessor type is supported now, but this API can be
> + * used for others in future.
> + */
> +int vas_register_coproc_api(struct module *mod);
> +void vas_unregister_coproc_api(void);
> +
> #endif /* __ASM_POWERPC_VAS_H */
> diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
> index 395789f..fe3f0fb 100644
> --- a/arch/powerpc/platforms/powernv/Makefile
> +++ b/arch/powerpc/platforms/powernv/Makefile
> @@ -17,7 +17,7 @@ obj-$(CONFIG_MEMORY_FAILURE) += opal-memory-errors.o
> obj-$(CONFIG_OPAL_PRD) += opal-prd.o
> obj-$(CONFIG_PERF_EVENTS) += opal-imc.o
> obj-$(CONFIG_PPC_MEMTRACE) += memtrace.o
> -obj-$(CONFIG_PPC_VAS) += vas.o vas-window.o vas-debug.o vas-fault.o
> +obj-$(CONFIG_PPC_VAS) += vas.o vas-window.o vas-debug.o vas-fault.o vas-api.o
> obj-$(CONFIG_OCXL_BASE) += ocxl.o
> obj-$(CONFIG_SCOM_DEBUGFS) += opal-xscom.o
> obj-$(CONFIG_PPC_SECURE_BOOT) += opal-secvar.o
> diff --git a/arch/powerpc/platforms/powernv/vas-api.c b/arch/powerpc/platforms/powernv/vas-api.c
> new file mode 100644
> index 0000000..3473a4a
> --- /dev/null
> +++ b/arch/powerpc/platforms/powernv/vas-api.c
> @@ -0,0 +1,290 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * VAS user space API for its accelerators (Only NX-GZIP is supported now)
> + * Copyright (C) 2019 Haren Myneni, IBM Corp
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/device.h>
> +#include <linux/cdev.h>
> +#include <linux/fs.h>
> +#include <linux/slab.h>
> +#include <linux/uaccess.h>
> +#include <asm/vas.h>
> +#include <uapi/asm/vas-api.h>
> +#include "vas.h"
> +
> +/*
> + * The driver creates the device node that can be used as follows:
> + * For NX-GZIP
> + *
> + * fd = open("/dev/crypto/nx-gzip", O_RDWR);
> + * rc = ioctl(fd, VAS_TX_WIN_OPEN, &attr);
> + * paste_addr = mmap(NULL, PAGE_SIZE, prot, MAP_SHARED, fd, 0ULL).
> + * vas_copy(&crb, 0, 1);
> + * vas_paste(paste_addr, 0, 1);
> + * close(fd) or exit process to close window.
> + *
> + * where "vas_copy" and "vas_paste" are defined in copy-paste.h.
> + * copy/paste returns to the user space directly. So refer NX hardware
> + * documententation for excat copy/paste usage and completion / error
> + * conditions.
> + */
> +
> +static char *coproc_dev_name = "nx-gzip";
> +static atomic_t coproc_instid = ATOMIC_INIT(0);
> +
> +/*
> + * Wrapper object for the nx-gzip device - there is just one instance of
> + * this node for the whole system.
> + */
> +static struct coproc_dev {
> + struct cdev cdev;
> + struct device *device;
> + char *name;
> + dev_t devt;
> + struct class *class;
> +} coproc_device;
> +
> +/*
> + * One instance per open of a nx-gzip device. Each coproc_instance is
> + * associated with a VAS window after the caller issues
> + * VAS_GZIP_TX_WIN_OPEN ioctl.
> + */
> +struct coproc_instance {
> + int id;
> + struct vas_window *txwin;
> +};
> +
> +static char *coproc_devnode(struct device *dev, umode_t *mode)
> +{
> + return kasprintf(GFP_KERNEL, "crypto/%s", dev_name(dev));
> +}
> +
> +static int coproc_open(struct inode *inode, struct file *fp)
> +{
> + struct coproc_instance *instance;
> +
> + instance = kzalloc(sizeof(*instance), GFP_KERNEL);
> + if (!instance)
> + return -ENOMEM;
> +
> + instance->id = atomic_inc_return(&coproc_instid);
I don't understand what this instance->id field does - I can't find any
other uses of it in these series.
I'm also not sure that this gives you a unique id - you increment it
here and decrement it in coproc_release, but I'm not sure what prevents
the same ID being given to multiple instances, e.g. the following
sequence
coproc_open(inode, file A) -> instance with id 0, coproc_instid = 1
coproc_open(inode, file B) -> instance with id 1, coproc_instid = 2
coproc_release(inode, file A) -> release id 0, coproc_instid = 1
coproc_open(inode, file C) -> instance with id 1, coproc_instid = 2
File B and C both have ID = 1, unless I'm misunderstanding something.
> +
> + fp->private_data = instance;
> + return 0;
> +}
> +
> +static int coproc_ioc_tx_win_open(struct file *fp, unsigned long arg)
> +{
> + int rc, vasid;
> + struct vas_tx_win_attr txattr;
> + struct vas_tx_win_open_attr uattr;
> + void __user *uptr = (void __user *)arg;
> + struct vas_window *txwin;
> + struct coproc_instance *nxti = fp->private_data;
> +
> + if (!nxti)
> + return -EINVAL;
> +
> + /*
> + * One window for file descriptor
> + */
> + if (nxti->txwin)
> + return -EEXIST;
> +
> + rc = copy_from_user(&uattr, uptr, sizeof(uattr));
> + if (rc) {
> + pr_err("%s(): copy_from_user() returns %d\n", __func__, rc);
> + return -EFAULT;
> + }
> +
> + if (uattr.version != 1) {
> + pr_err("Invalid version\n");
> + return -EINVAL;
> + }
> +
> + vasid = uattr.vas_id;
> +
> + memset(&txattr, 0, sizeof(struct vas_tx_win_attr));
You could define txattr with `struct vas_tx_win_attr txattr = {};` and
avoid the explicit memset.
> + vas_init_tx_win_attr(&txattr, VAS_COP_TYPE_GZIP);
> +
> + txattr.lpid = mfspr(SPRN_LPID);
> + txattr.pidr = mfspr(SPRN_PID);
> + txattr.user_win = true;
> + txattr.rsvd_txbuf_count = false;
> + txattr.pswid = false;
> + /*
> + * txattr.wcreds_max is set to VAS_WCREDS_DEFAULT (1024) in
> + * vas-window.c, but can be changed specific to GZIP depends
> + * on user space need.
> + * If needed to set txattr.wcreds_max here.
> + */
Who could set this? You mention userspace need but it looks like the
user cannot set this. Is this a message to future kernel developers?
> +
> + pr_devel("Pid %d: Opening txwin, PIDR %ld\n", txattr.pidr,
> + mfspr(SPRN_PID));
> +
> + txwin = vas_tx_win_open(vasid, VAS_COP_TYPE_GZIP, &txattr);
> + if (IS_ERR(txwin)) {
> + pr_err("%s() vas_tx_win_open() failed, %ld\n", __func__,
> + PTR_ERR(txwin));
> + return PTR_ERR(txwin);
> + }
> +
> + nxti->txwin = txwin;
> +
> + return 0;
> +}
> +
> +static int coproc_release(struct inode *inode, struct file *fp)
> +{
> + struct coproc_instance *instance;
> +
> + instance = fp->private_data;
> +
> + if (instance && instance->txwin) {
> + vas_win_close(instance->txwin);
> + instance->txwin = NULL;
> + }
> +
> + /*
> + * We don't know here if user has other receive windows
> + * open, so we can't really call clear_thread_tidr().
> + * So, once the process calls set_thread_tidr(), the
> + * TIDR value sticks around until process exits, resulting
> + * in an extra copy in restore_sprs().
> + */
> +
> + kfree(instance);
> + fp->private_data = NULL;
> + atomic_dec(&coproc_instid);
> +
> + return 0;
> +}
> +
> +static int coproc_mmap(struct file *fp, struct vm_area_struct *vma)
> +{
> + int rc;
> + pgprot_t prot;
> + u64 paste_addr;
> + unsigned long pfn;
> + struct coproc_instance *instance = fp->private_data;
> +
> + if ((vma->vm_end - vma->vm_start) > PAGE_SIZE) {
> + pr_debug("%s(): size 0x%zx, PAGE_SIZE 0x%zx\n", __func__,
> + (vma->vm_end - vma->vm_start), PAGE_SIZE);
> + return -EINVAL;
> + }
> +
> + /* Ensure instance has an open send window */
> + if (!instance->txwin) {
> + pr_err("%s(): No send window open?\n", __func__);
> + return -EINVAL;
> + }
> +
> + vas_win_paste_addr(instance->txwin, &paste_addr, NULL);
> + pfn = paste_addr >> PAGE_SHIFT;
> +
> + /* flags, page_prot from cxl_mmap(), except we want cachable */
> + vma->vm_flags |= VM_IO | VM_PFNMAP;
> + vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
> +
> + prot = __pgprot(pgprot_val(vma->vm_page_prot) | _PAGE_DIRTY);
> +
> + rc = remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
> + vma->vm_end - vma->vm_start, prot);
> +
> + pr_devel("%s(): paste addr %llx at %lx, rc %d\n", __func__,
> + paste_addr, vma->vm_start, rc);
> +
> + return rc;
> +}
> +
> +static long coproc_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
> +{
> + switch (cmd) {
> + case VAS_TX_WIN_OPEN:
> + return coproc_ioc_tx_win_open(fp, arg);
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static struct file_operations coproc_fops = {
> + .open = coproc_open,
> + .release = coproc_release,
> + .mmap = coproc_mmap,
> + .unlocked_ioctl = coproc_ioctl,
> +};
> +
> +/*
> + * Supporting only nx-gzip coprocessor type now, but this API code
> + * extended to other coprocessor types later.
> + */
> +int vas_register_coproc_api(struct module *mod)
> +{
> + int rc = -EINVAL;
> + dev_t devno;
> +
> + rc = alloc_chrdev_region(&coproc_device.devt, 1, 1, "nx-gzip");
> + if (rc) {
> + pr_err("Unable to allocate coproc major number: %i\n", rc);
> + return rc;
> + }
> +
> + pr_devel("NX-GZIP device allocated, dev [%i,%i]\n",
> + MAJOR(coproc_device.devt), MINOR(coproc_device.devt));
> +
> + coproc_device.class = class_create(mod, "nx-gzip");
> + if (IS_ERR(coproc_device.class)) {
> + rc = PTR_ERR(coproc_device.class);
> + pr_err("Unable to create NX-GZIP class %d\n", rc);
> + goto err_class;
> + }
> + coproc_device.class->devnode = coproc_devnode;
> +
> + coproc_fops.owner = mod;
> + cdev_init(&coproc_device.cdev, &coproc_fops);
Looking into this coproc_fops thing more:
I find this API very confusing. The comment at the top of the function
says it will be extended, but there's only one coproc_fops, so currently
it can only be instantiated once and owned by one module. Much of the
rest of that function is also very much based around the nx-gzip
coprocessor.
I'm not fully certain about how this should work, but I think probably
it either needs to be fully generic or fully nx-gzip only for now. I
would make it fully nx-gzip only and extend it later, but I'm not fussy.
> +
> + devno = MKDEV(MAJOR(coproc_device.devt), 0);
> + rc = cdev_add(&coproc_device.cdev, devno, 1);
> + if (rc) {
> + pr_err("cdev_add() failed %d\n", rc);
> + goto err_cdev;
> + }
> +
> + coproc_device.device = device_create(coproc_device.class, NULL,
> + devno, NULL, coproc_dev_name, MINOR(devno));
> + if (IS_ERR(coproc_device.device)) {
> + rc = PTR_ERR(coproc_device.device);
> + pr_err("Unable to create coproc-%d %d\n", MINOR(devno), rc);
> + goto err;
> + }
> +
> + pr_devel("%s: Added dev [%d,%d]\n", __func__, MAJOR(devno),
> + MINOR(devno));
> +
> + return 0;
> +
> +err:
> + cdev_del(&coproc_device.cdev);
> +err_cdev:
> + class_destroy(coproc_device.class);
> +err_class:
> + unregister_chrdev_region(coproc_device.devt, 1);
> + return rc;
> +}
> +EXPORT_SYMBOL_GPL(vas_register_coproc_api);
> +
> +void vas_unregister_coproc_api(void)
> +{
> + dev_t devno;
> +
> + cdev_del(&coproc_device.cdev);
> + devno = MKDEV(MAJOR(coproc_device.devt), 0);
> + device_destroy(coproc_device.class, devno);
> +
> + class_destroy(coproc_device.class);
> + unregister_chrdev_region(coproc_device.devt, 1);
> +}
> +EXPORT_SYMBOL_GPL(vas_unregister_coproc_api);
> diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c
> index e9ab851..7484296 100644
> --- a/arch/powerpc/platforms/powernv/vas-window.c
> +++ b/arch/powerpc/platforms/powernv/vas-window.c
> @@ -26,7 +26,7 @@
> * Compute the paste address region for the window @window using the
> * ->paste_base_addr and ->paste_win_id_shift we got from device tree.
> */
> -static void compute_paste_address(struct vas_window *window, u64 *addr, int *len)
> +void vas_win_paste_addr(struct vas_window *window, u64 *addr, int *len)
> {
> int winid;
> u64 base, shift;
> @@ -80,7 +80,7 @@ static void *map_paste_region(struct vas_window *txwin)
> goto free_name;
>
> txwin->paste_addr_name = name;
> - compute_paste_address(txwin, &start, &len);
> + vas_win_paste_addr(txwin, &start, &len);
>
> if (!request_mem_region(start, len, name)) {
> pr_devel("%s(): request_mem_region(0x%llx, %d) failed\n",
> @@ -138,7 +138,7 @@ static void unmap_paste_region(struct vas_window *window)
> u64 busaddr_start;
>
> if (window->paste_kaddr) {
> - compute_paste_address(window, &busaddr_start, &len);
> + vas_win_paste_addr(window, &busaddr_start, &len);
> unmap_region(window->paste_kaddr, busaddr_start, len);
> window->paste_kaddr = NULL;
> kfree(window->paste_addr_name);
> diff --git a/arch/powerpc/platforms/powernv/vas.h b/arch/powerpc/platforms/powernv/vas.h
> index 8c39a7d..a10abed 100644
> --- a/arch/powerpc/platforms/powernv/vas.h
> +++ b/arch/powerpc/platforms/powernv/vas.h
> @@ -431,6 +431,8 @@ struct vas_winctx {
> extern void vas_return_credit(struct vas_window *window, bool tx);
> extern struct vas_window *vas_pswid_to_window(struct vas_instance *vinst,
> uint32_t pswid);
> +extern void vas_win_paste_addr(struct vas_window *window, u64 *addr,
> + int *len);
>
> static inline int vas_window_pid(struct vas_window *window)
> {
> --
> 1.8.3.1
