Re: [PATCH v5 04/17] powerpc/vas: Add platform specific user window operations

[Haren Myneni <haren@linux.ibm.com>]

On Mon, 2021-06-14 at 12:24 +1000, Nicholas Piggin wrote:
> Excerpts from Haren Myneni's message of June 13, 2021 8:57 pm:
> > PowerNV uses registers to open/close VAS windows, and getting the
> > paste address. Whereas the hypervisor calls are used on PowerVM.
> > 
> > This patch adds the platform specific user space window operations
> > and register with the common VAS user space interface.
> > 
> > Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> > ---
> >  arch/powerpc/include/asm/vas.h              | 14 +++++-
> >  arch/powerpc/platforms/book3s/vas-api.c     | 53 +++++++++++++--
> > ------
> >  arch/powerpc/platforms/powernv/vas-window.c | 45 ++++++++++++++++-
> >  3 files changed, 89 insertions(+), 23 deletions(-)
> > 
> > diff --git a/arch/powerpc/include/asm/vas.h
> > b/arch/powerpc/include/asm/vas.h
> > index bab7891d43f5..85318d7446c7 100644
> > --- a/arch/powerpc/include/asm/vas.h
> > +++ b/arch/powerpc/include/asm/vas.h
> > @@ -5,6 +5,7 @@
> >  
> >  #ifndef _ASM_POWERPC_VAS_H
> >  #define _ASM_POWERPC_VAS_H
> > +#include <uapi/asm/vas-api.h>
> >  
> >  struct vas_window;
> >  
> > @@ -48,6 +49,16 @@ enum vas_cop_type {
> >  	VAS_COP_TYPE_MAX,
> >  };
> >  
> > +/*
> > + * User space window operations used for powernv and powerVM
> > + */
> > +struct vas_user_win_ops {
> > +	struct vas_window * (*open_win)(struct vas_tx_win_open_attr *,
> > +				enum vas_cop_type);
> > +	u64 (*paste_addr)(struct vas_window *);
> > +	int (*close_win)(struct vas_window *);
> > +};
> 
> This looks better, but rather than pull in uapi and the user API 
> structure here, could you just pass in vas_id and flags after the
> common 
> code does the user copy and verifies the version and other details?
> 
> I think it's generally good practice to limit the data that the usre
> can influence as much as possible. Sorry for not picking up on that
> earlier.

The user space pass vas_tx_win_open_attr struct - use only vas_id and
flags right now but it can be extended in future with reserve elements.
So passing the same struct to platform specific API.

do you prefer "struct vas_window * (*open_win)(vas_id, flags, cop)" and
extend later when more elments are used?

Thanks
Haren 

> 
> If that's changed, then
> 
> Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
> 
> Thanks,
> Nick
> 
> > +
> >  /*
> >   * Receive window attributes specified by the (in-kernel) owner of
> > window.
> >   */
> > @@ -175,7 +186,8 @@ void vas_unregister_api_powernv(void);
> >   * used for others in future.
> >   */
> >  int vas_register_coproc_api(struct module *mod, enum vas_cop_type
> > cop_type,
> > -				const char *name);
> > +			    const char *name,
> > +			    const struct vas_user_win_ops *vops);
> >  void vas_unregister_coproc_api(void);
> >  
> >  #endif /* __ASM_POWERPC_VAS_H */
> > diff --git a/arch/powerpc/platforms/book3s/vas-api.c
> > b/arch/powerpc/platforms/book3s/vas-api.c
> > index 72c126d87216..7cfc4b435ae8 100644
> > --- a/arch/powerpc/platforms/book3s/vas-api.c
> > +++ b/arch/powerpc/platforms/book3s/vas-api.c
> > @@ -42,6 +42,7 @@ static struct coproc_dev {
> >  	dev_t devt;
> >  	struct class *class;
> >  	enum vas_cop_type cop_type;
> > +	const struct vas_user_win_ops *vops;
> >  } coproc_device;
> >  
> >  struct coproc_instance {
> > @@ -72,11 +73,10 @@ static int coproc_open(struct inode *inode,
> > struct file *fp)
> >  static int coproc_ioc_tx_win_open(struct file *fp, unsigned long
> > arg)
> >  {
> >  	void __user *uptr = (void __user *)arg;
> > -	struct vas_tx_win_attr txattr = {};
> >  	struct vas_tx_win_open_attr uattr;
> >  	struct coproc_instance *cp_inst;
> >  	struct vas_window *txwin;
> > -	int rc, vasid;
> > +	int rc;
> >  
> >  	cp_inst = fp->private_data;
> >  
> > @@ -93,27 +93,20 @@ static int coproc_ioc_tx_win_open(struct file
> > *fp, unsigned long arg)
> >  	}
> >  
> >  	if (uattr.version != 1) {
> > -		pr_err("Invalid version\n");
> > +		pr_err("Invalid window open API version\n");
> >  		return -EINVAL;
> >  	}
> >  
> > -	vasid = uattr.vas_id;
> > -
> > -	vas_init_tx_win_attr(&txattr, cp_inst->coproc->cop_type);
> > -
> > -	txattr.lpid = mfspr(SPRN_LPID);
> > -	txattr.pidr = mfspr(SPRN_PID);
> > -	txattr.user_win = true;
> > -	txattr.rsvd_txbuf_count = false;
> > -	txattr.pswid = false;
> > -
> > -	pr_devel("Pid %d: Opening txwin, PIDR %ld\n", txattr.pidr,
> > -				mfspr(SPRN_PID));
> > +	if (!cp_inst->coproc->vops && !cp_inst->coproc->vops->open_win) 
> > {
> > +		pr_err("VAS API is not registered\n");
> > +		return -EACCES;
> > +	}
> >  
> > -	txwin = vas_tx_win_open(vasid, cp_inst->coproc->cop_type,
> > &txattr);
> > +	txwin = cp_inst->coproc->vops->open_win(&uattr,
> > +						cp_inst->coproc-
> > >cop_type);
> >  	if (IS_ERR(txwin)) {
> > -		pr_err("%s() vas_tx_win_open() failed, %ld\n",
> > __func__,
> > -					PTR_ERR(txwin));
> > +		pr_err("%s() VAS window open failed, %ld\n", __func__,
> > +				PTR_ERR(txwin));
> >  		return PTR_ERR(txwin);
> >  	}
> >  
> > @@ -125,9 +118,15 @@ static int coproc_ioc_tx_win_open(struct file
> > *fp, unsigned long arg)
> >  static int coproc_release(struct inode *inode, struct file *fp)
> >  {
> >  	struct coproc_instance *cp_inst = fp->private_data;
> > +	int rc;
> >  
> >  	if (cp_inst->txwin) {
> > -		vas_win_close(cp_inst->txwin);
> > +		if (cp_inst->coproc->vops &&
> > +			cp_inst->coproc->vops->close_win) {
> > +			rc = cp_inst->coproc->vops->close_win(cp_inst-
> > >txwin);
> > +			if (rc)
> > +				return rc;
> > +		}
> >  		cp_inst->txwin = NULL;
> >  	}
> >  
> > @@ -168,7 +167,17 @@ static int coproc_mmap(struct file *fp, struct
> > vm_area_struct *vma)
> >  		return -EINVAL;
> >  	}
> >  
> > -	vas_win_paste_addr(txwin, &paste_addr, NULL);
> > +	if (!cp_inst->coproc->vops && !cp_inst->coproc->vops-
> > >paste_addr) {
> > +		pr_err("%s(): VAS API is not registered\n", __func__);
> > +		return -EACCES;
> > +	}
> > +
> > +	paste_addr = cp_inst->coproc->vops->paste_addr(txwin);
> > +	if (!paste_addr) {
> > +		pr_err("%s(): Window paste address failed\n",
> > __func__);
> > +		return -EINVAL;
> > +	}
> > +
> >  	pfn = paste_addr >> PAGE_SHIFT;
> >  
> >  	/* flags, page_prot from cxl_mmap(), except we want cachable */
> > @@ -208,7 +217,8 @@ static struct file_operations coproc_fops = {
> >   * extended to other coprocessor types later.
> >   */
> >  int vas_register_coproc_api(struct module *mod, enum vas_cop_type
> > cop_type,
> > -				const char *name)
> > +			    const char *name,
> > +			    const struct vas_user_win_ops *vops)
> >  {
> >  	int rc = -EINVAL;
> >  	dev_t devno;
> > @@ -230,6 +240,7 @@ int vas_register_coproc_api(struct module *mod,
> > enum vas_cop_type cop_type,
> >  	}
> >  	coproc_device.class->devnode = coproc_devnode;
> >  	coproc_device.cop_type = cop_type;
> > +	coproc_device.vops = vops;
> >  
> >  	coproc_fops.owner = mod;
> >  	cdev_init(&coproc_device.cdev, &coproc_fops);
> > diff --git a/arch/powerpc/platforms/powernv/vas-window.c
> > b/arch/powerpc/platforms/powernv/vas-window.c
> > index 41712b4b268e..5162e95c4090 100644
> > --- a/arch/powerpc/platforms/powernv/vas-window.c
> > +++ b/arch/powerpc/platforms/powernv/vas-window.c
> > @@ -16,6 +16,7 @@
> >  #include <linux/mmu_context.h>
> >  #include <asm/switch_to.h>
> >  #include <asm/ppc-opcode.h>
> > +#include <asm/vas.h>
> >  #include "vas.h"
> >  #include "copy-paste.h"
> >  
> > @@ -1443,6 +1444,48 @@ struct vas_window
> > *vas_pswid_to_window(struct vas_instance *vinst,
> >  	return window;
> >  }
> >  
> > +static struct vas_window *vas_user_win_open(struct
> > vas_tx_win_open_attr *uattr,
> > +				enum vas_cop_type cop_type)
> > +{
> > +	struct vas_tx_win_attr txattr = {};
> > +
> > +	vas_init_tx_win_attr(&txattr, cop_type);
> > +
> > +	txattr.lpid = mfspr(SPRN_LPID);
> > +	txattr.pidr = mfspr(SPRN_PID);
> > +	txattr.user_win = true;
> > +	txattr.rsvd_txbuf_count = false;
> > +	txattr.pswid = false;
> > +
> > +	pr_devel("Pid %d: Opening txwin, PIDR %ld\n", txattr.pidr,
> > +				mfspr(SPRN_PID));
> > +
> > +	return vas_tx_win_open(uattr->vas_id, cop_type, &txattr);
> > +}
> > +
> > +static u64 vas_user_win_paste_addr(struct vas_window *win)
> > +{
> > +	u64 paste_addr;
> > +
> > +	vas_win_paste_addr(win, &paste_addr, NULL);
> > +
> > +	return paste_addr;
> > +}
> > +
> > +static int vas_user_win_close(struct vas_window *txwin)
> > +{
> > +
> > +	vas_win_close(txwin);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct vas_user_win_ops vops =  {
> > +	.open_win	=	vas_user_win_open,
> > +	.paste_addr	=	vas_user_win_paste_addr,
> > +	.close_win	=	vas_user_win_close,
> > +};
> > +
> >  /*
> >   * Supporting only nx-gzip coprocessor type now, but this API code
> >   * extended to other coprocessor types later.
> > @@ -1451,7 +1494,7 @@ int vas_register_api_powernv(struct module
> > *mod, enum vas_cop_type cop_type,
> >  			     const char *name)
> >  {
> >  
> > -	return vas_register_coproc_api(mod, cop_type, name);
> > +	return vas_register_coproc_api(mod, cop_type, name, &vops);
> >  }
> >  EXPORT_SYMBOL_GPL(vas_register_api_powernv);
> >  
> > -- 
> > 2.18.2
> > 
> > 
> >