Re: [PATCH v5] tee: Use iov_iter to better support shared buffer registration
From: Jens Wiklander
Date: Tue Dec 12 2023 - 04:23:38 EST
On Tue, Dec 12, 2023 at 6:25 AM Sumit Garg <sumit.garg@xxxxxxxxxx> wrote:
>
> On Tue, 5 Dec 2023 at 21:53, Arnaud Pouliquen
> <arnaud.pouliquen@xxxxxxxxxxx> wrote:
> >
> > Currently it's not possible to register kernel buffers with TEE
> > which are allocated via vmalloc.
> >
> > Use iov_iter and associated helper functions to manage the page
> > registration for all type of memories.
> >
> > Suggested-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> > Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxxxxxxx>
> > ---
> > Update from V4 to V5:
> > - replace import_ubuf() by iov_iter_ubuf(),
> > - fix comment in register_shm_helper() function.
> >
>
> Looks good to me, feel free to add:
>
> Reviewed-by: Sumit Garg <sumit.garg@xxxxxxxxxx>
I'm picking up this.
Thanks,
Jens
>
> > Update from V3 to V4:
> > - improve commit message,
> > - use import_ubuf() instead of iov_iter_init(),
> > - move shm_get_kernel_pages in register_shm_helper,
> > - put back untagged_addr in register_shm_helper(),
> > - move the comment related to pin pages from shm_get_kernel_pages()
> > to register_shm_helper().
> >
> > Update from V2 to V3:
> > - break lines longer than 80 columns.
> >
> > Update from V1 to V2:
> > - replace ITER_SOURCE by ITER_DEST flag in tee_shm_register_user_buf(),
> > - replace IS_ERR_OR NULL(shm) by IS_ERR(shm) in tee_shm_register_user_buf().
> >
> > V1:
> > The support of buffer registration allocated with vmalloc is no more
> > available since c83900393aa1 ("tee: Remove vmalloc page support").
> >
> > This patch is an alternative to a revert and resulted from a discussion
> > with Christopher Hellwig [1].
> >
> > This patch has been tested using xtest tool in optee qemu environment [2]
> > and using the series related to the remoteproc tee that should be
> > proposed soon [3].
> >
> > References:
> > [1] https://lore.kernel.org/linux-arm-kernel/18a8528d-7d9d-6ed0-0045-5ee47dd39fb2@xxxxxxxxxxx/T/#m8ec683c44fcd9b69c2aee42eaed0793afac9dd18in
> > [2] https://optee.readthedocs.io/en/latest/building/devices/qemu.html#build-instructions
> > [3] https://lore.kernel.org/linux-arm-kernel/18a8528d-7d9d-6ed0-0045-5ee47dd39fb2@xxxxxxxxxxx/T/#maca0a1fc897aadd54c7deac432e11473fe970d1d
> > ---
> > drivers/tee/tee_shm.c | 78 +++++++++++++++++++++++--------------------
> > 1 file changed, 42 insertions(+), 36 deletions(-)
> >
> > diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> > index 673cf0359494..731d9028b67f 100644
> > --- a/drivers/tee/tee_shm.c
> > +++ b/drivers/tee/tee_shm.c
> > @@ -22,23 +22,12 @@ static void shm_put_kernel_pages(struct page **pages, size_t page_count)
> > put_page(pages[n]);
> > }
> >
> > -static int shm_get_kernel_pages(unsigned long start, size_t page_count,
> > - struct page **pages)
> > +static void shm_get_kernel_pages(struct page **pages, size_t page_count)
> > {
> > - struct page *page;
> > size_t n;
> >
> > - if (WARN_ON_ONCE(is_vmalloc_addr((void *)start) ||
> > - is_kmap_addr((void *)start)))
> > - return -EINVAL;
> > -
> > - page = virt_to_page((void *)start);
> > - for (n = 0; n < page_count; n++) {
> > - pages[n] = page + n;
> > + for (n = 0; n < page_count; n++)
> > get_page(pages[n]);
> > - }
> > -
> > - return page_count;
> > }
> >
> > static void release_registered_pages(struct tee_shm *shm)
> > @@ -214,13 +203,14 @@ struct tee_shm *tee_shm_alloc_priv_buf(struct tee_context *ctx, size_t size)
> > EXPORT_SYMBOL_GPL(tee_shm_alloc_priv_buf);
> >
> > static struct tee_shm *
> > -register_shm_helper(struct tee_context *ctx, unsigned long addr,
> > - size_t length, u32 flags, int id)
> > +register_shm_helper(struct tee_context *ctx, struct iov_iter *iter, u32 flags,
> > + int id)
> > {
> > struct tee_device *teedev = ctx->teedev;
> > struct tee_shm *shm;
> > - unsigned long start;
> > - size_t num_pages;
> > + unsigned long start, addr;
> > + size_t num_pages, off;
> > + ssize_t len;
> > void *ret;
> > int rc;
> >
> > @@ -245,31 +235,38 @@ register_shm_helper(struct tee_context *ctx, unsigned long addr,
> > shm->flags = flags;
> > shm->ctx = ctx;
> > shm->id = id;
> > - addr = untagged_addr(addr);
> > + addr = untagged_addr((unsigned long)iter_iov_addr(iter));
> > start = rounddown(addr, PAGE_SIZE);
> > - shm->offset = addr - start;
> > - shm->size = length;
> > - num_pages = (roundup(addr + length, PAGE_SIZE) - start) / PAGE_SIZE;
> > + num_pages = iov_iter_npages(iter, INT_MAX);
> > + if (!num_pages) {
> > + ret = ERR_PTR(-ENOMEM);
> > + goto err_ctx_put;
> > + }
> > +
> > shm->pages = kcalloc(num_pages, sizeof(*shm->pages), GFP_KERNEL);
> > if (!shm->pages) {
> > ret = ERR_PTR(-ENOMEM);
> > goto err_free_shm;
> > }
> >
> > - if (flags & TEE_SHM_USER_MAPPED)
> > - rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE,
> > - shm->pages);
> > - else
> > - rc = shm_get_kernel_pages(start, num_pages, shm->pages);
> > - if (rc > 0)
> > - shm->num_pages = rc;
> > - if (rc != num_pages) {
> > - if (rc >= 0)
> > - rc = -ENOMEM;
> > - ret = ERR_PTR(rc);
> > - goto err_put_shm_pages;
> > + len = iov_iter_extract_pages(iter, &shm->pages, LONG_MAX, num_pages, 0,
> > + &off);
> > + if (unlikely(len <= 0)) {
> > + ret = len ? ERR_PTR(len) : ERR_PTR(-ENOMEM);
> > + goto err_free_shm_pages;
> > }
> >
> > + /*
> > + * iov_iter_extract_kvec_pages does not get reference on the pages,
> > + * get a reference on them.
> > + */
> > + if (iov_iter_is_kvec(iter))
> > + shm_get_kernel_pages(shm->pages, num_pages);
> > +
> > + shm->offset = off;
> > + shm->size = len;
> > + shm->num_pages = num_pages;
> > +
> > rc = teedev->desc->ops->shm_register(ctx, shm, shm->pages,
> > shm->num_pages, start);
> > if (rc) {
> > @@ -279,10 +276,11 @@ register_shm_helper(struct tee_context *ctx, unsigned long addr,
> >
> > return shm;
> > err_put_shm_pages:
> > - if (flags & TEE_SHM_USER_MAPPED)
> > + if (!iov_iter_is_kvec(iter))
> > unpin_user_pages(shm->pages, shm->num_pages);
> > else
> > shm_put_kernel_pages(shm->pages, shm->num_pages);
> > +err_free_shm_pages:
> > kfree(shm->pages);
> > err_free_shm:
> > kfree(shm);
> > @@ -307,6 +305,7 @@ struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx,
> > u32 flags = TEE_SHM_USER_MAPPED | TEE_SHM_DYNAMIC;
> > struct tee_device *teedev = ctx->teedev;
> > struct tee_shm *shm;
> > + struct iov_iter iter;
> > void *ret;
> > int id;
> >
> > @@ -319,7 +318,8 @@ struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx,
> > if (id < 0)
> > return ERR_PTR(id);
> >
> > - shm = register_shm_helper(ctx, addr, length, flags, id);
> > + iov_iter_ubuf(&iter, ITER_DEST, (void __user *)addr, length);
> > + shm = register_shm_helper(ctx, &iter, flags, id);
> > if (IS_ERR(shm)) {
> > mutex_lock(&teedev->mutex);
> > idr_remove(&teedev->idr, id);
> > @@ -352,8 +352,14 @@ struct tee_shm *tee_shm_register_kernel_buf(struct tee_context *ctx,
> > void *addr, size_t length)
> > {
> > u32 flags = TEE_SHM_DYNAMIC;
> > + struct kvec kvec;
> > + struct iov_iter iter;
> > +
> > + kvec.iov_base = addr;
> > + kvec.iov_len = length;
> > + iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, length);
> >
> > - return register_shm_helper(ctx, (unsigned long)addr, length, flags, -1);
> > + return register_shm_helper(ctx, &iter, flags, -1);
> > }
> > EXPORT_SYMBOL_GPL(tee_shm_register_kernel_buf);
> >
> > --
> > 2.25.1
> >