linux-kernel - Re: [PATCH v4 1/2] tee: enable support to register kernel memory

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Message-ID: <CAFA6WYM_nxkW69Ln2Dd0KconCRN6GfFdmE0ai4rS4MZUN7OQyw@mail.gmail.com>
Date:   Wed, 25 Mar 2020 14:18:27 +0530
From:   Sumit Garg <sumit.garg@...aro.org>
To:     Jens Wiklander <jens.wiklander@...aro.org>
Cc:     "tee-dev @ lists . linaro . org" <tee-dev@...ts.linaro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Stuart Yoder <stuart.yoder@....com>,
        Daniel Thompson <daniel.thompson@...aro.org>
Subject: Re: [PATCH v4 1/2] tee: enable support to register kernel memory

Hi Jens,

On Wed, 25 Mar 2020 at 14:00, Jens Wiklander <jens.wiklander@...aro.org> wrote:
>
> Hi Sumit,
>
> On Mon, Mar 23, 2020 at 1:19 PM Sumit Garg <sumit.garg@...aro.org> wrote:
> >
> > Enable support to register kernel memory reference with TEE. This change
> > will allow TEE bus drivers to register memory references.
> >
> > Signed-off-by: Sumit Garg <sumit.garg@...aro.org>
> > ---
> >  drivers/tee/tee_shm.c   | 26 ++++++++++++++++++++++++--
> >  include/linux/tee_drv.h |  1 +
> >  2 files changed, 25 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> > index 937ac5a..b88274c 100644
> > --- a/drivers/tee/tee_shm.c
> > +++ b/drivers/tee/tee_shm.c
> > @@ -9,6 +9,7 @@
> >  #include <linux/sched.h>
> >  #include <linux/slab.h>
> >  #include <linux/tee_drv.h>
> > +#include <linux/uio.h>
> >  #include "tee_private.h"
> >
> >  static void tee_shm_release(struct tee_shm *shm)
> > @@ -218,13 +219,14 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> >  {
> >         struct tee_device *teedev = ctx->teedev;
> >         const u32 req_flags = TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED;
> > +       const u32 req_ker_flags = TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED;
>
> I'd prefer naming these two "req_user_flags" and "req_kernel_flags".
>

Okay, will update these in the next version.

-Sumit

> Thanks,
> Jens
>
> >         struct tee_shm *shm;
> >         void *ret;
> >         int rc;
> >         int num_pages;
> >         unsigned long start;
> >
> > -       if (flags != req_flags)
> > +       if (flags != req_flags && flags != req_ker_flags)
> >                 return ERR_PTR(-ENOTSUPP);
> >
> >         if (!tee_device_get(teedev))
> > @@ -259,7 +261,27 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> >                 goto err;
> >         }
> >
> > -       rc = get_user_pages_fast(start, num_pages, FOLL_WRITE, shm->pages);
> > +       if (flags & TEE_SHM_USER_MAPPED) {
> > +               rc = get_user_pages_fast(start, num_pages, FOLL_WRITE,
> > +                                        shm->pages);
> > +       } else {
> > +               struct kvec *kiov;
> > +               int i;
> > +
> > +               kiov = kcalloc(num_pages, sizeof(*kiov), GFP_KERNEL);
> > +               if (!kiov) {
> > +                       ret = ERR_PTR(-ENOMEM);
> > +                       goto err;
> > +               }
> > +
> > +               for (i = 0; i < num_pages; i++) {
> > +                       kiov[i].iov_base = (void *)(start + i * PAGE_SIZE);
> > +                       kiov[i].iov_len = PAGE_SIZE;
> > +               }
> > +
> > +               rc = get_kernel_pages(kiov, num_pages, 0, shm->pages);
> > +               kfree(kiov);
> > +       }
> >         if (rc > 0)
> >                 shm->num_pages = rc;
> >         if (rc != num_pages) {
> > diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
> > index 7a03f68..dedf8fa 100644
> > --- a/include/linux/tee_drv.h
> > +++ b/include/linux/tee_drv.h
> > @@ -26,6 +26,7 @@
> >  #define TEE_SHM_REGISTER       BIT(3)  /* Memory registered in secure world */
> >  #define TEE_SHM_USER_MAPPED    BIT(4)  /* Memory mapped in user space */
> >  #define TEE_SHM_POOL           BIT(5)  /* Memory allocated from pool */
> > +#define TEE_SHM_KERNEL_MAPPED  BIT(6)  /* Memory mapped in kernel space */
> >
> >  struct device;
> >  struct tee_device;
> > --
> > 2.7.4
> >