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From: Haren Myneni <haren@linux.ibm.com>
To: Daniel Axtens <dja@axtens.net>
Cc: herbert@gondor.apana.org.au, mikey@neuling.org,
	npiggin@gmail.com, linux-crypto@vger.kernel.org,
	sukadev@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v3 3/9] powerpc/vas: Add VAS user space API
Date: Sun, 22 Mar 2020 13:50:18 -0700	[thread overview]
Message-ID: <1584910218.9256.15285.camel@hbabu-laptop> (raw)
In-Reply-To: <87fte3w775.fsf@dja-thinkpad.axtens.net>

On Fri, 2020-03-20 at 23:18 +1100, Daniel Axtens wrote:
> Haren Myneni <haren@linux.ibm.com> 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@linux.vnet.ibm.com>
> > Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> > ---
> >  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.

Thanks for your comments. 

coproc_instid is not needed. Sorry My mistake, it was added in prototype
code, but forgot to remove. Added to determine how many windows are
active, but not needed now. 

I will repost the patch with this change.

> 
> > +
> > +	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?

set the default value in vax_tx_win_open() (vas_window.c) if it is not
set here. credits limit can set here if we decide to use non-default
value for user space windows. Not allowing user space to set this value.
Yes, this comment is for kernel developers. 

I can remove this comment to remove the confusion.  

> 
> > +
> > +	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.

We are adding only for NX-GZIP right now and mentioned nx-gzip. Most of
interfaces in coproc_fops such as open/mmap/close should be common for
any coprocs except ioctl or new ioctl cmd. 

register_coproc_api creates device node and register fs API specific to
coprocessor. user space use fs API to establish communication channel
(using open, ioctl, mmap) to NX.

How about defining coproc_nxgzip_fs to remove this confusion. 

> 
> > +
> > +	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



  reply	other threads:[~2020-03-22 20:51 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-07  0:27 [PATCH v3 0/9] crypto/nx: Enable GZIP engine and provide userpace API Haren Myneni
2020-03-07  0:32 ` [PATCH v3 1/9] powerpc/vas: Initialize window attributes for GZIP coprocessor type Haren Myneni
2020-03-07  0:32 ` [PATCH v3 2/9] powerpc/vas: Define VAS_TX_WIN_OPEN ioctl API Haren Myneni
2020-03-07  0:33 ` [PATCH v3 3/9] powerpc/vas: Add VAS user space API Haren Myneni
2020-03-18  7:12   ` Daniel Axtens
2020-03-19  1:16   ` Daniel Axtens
2020-03-19  1:53     ` Haren Myneni
2020-03-20 12:18   ` Daniel Axtens
2020-03-22 20:50     ` Haren Myneni [this message]
2020-03-07  0:34 ` [PATCH v3 4/9] crypto/nx: Initialize coproc entry with kzalloc Haren Myneni
2020-03-07  0:34 ` [PATCH v3 5/9] crypto/nx: Rename nx-842-powernv file name to nx-common-powernv Haren Myneni
2020-03-07  0:36 ` [PATCH v3 6/9] crypto/NX: Make enable code generic to add new GZIP compression type Haren Myneni
2020-03-07  0:37 ` [PATCH v3 7/9] crypto/nx: Enable and setup GZIP compresstion type Haren Myneni
2020-03-07  0:38 ` [PATCH v3 8/9] crypto/nx: Remove 'pid' in vas_tx_win_attr struct Haren Myneni
2020-03-07  0:39 ` [PATCH v3 9/9] Documentation/powerpc: VAS API Haren Myneni
2020-03-20 12:24   ` Daniel Axtens
2020-03-23  0:54     ` Haren Myneni
2020-03-23  8:32   ` Nicholas Piggin
2020-03-16 13:04 ` [PATCH v3 0/9] crypto/nx: Enable GZIP engine and provide userpace API Daniel Axtens
2020-03-16 23:31   ` Haren Myneni
  -- strict thread matches above, loose matches on Subject: below --
2020-02-29 11:04 [PATCH V2 " Haren Myneni
2020-02-29 11:14 ` [PATCH V3 3/9] powerpc/vas: Add VAS user space API Haren Myneni

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