Messages in this thread | | | From | Sumit Garg <> | Date | Wed, 29 Nov 2023 12:27:22 +0530 | Subject | Re: [PATCH v3] tee: Use iov_iter to better support shared buffer registration |
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Hi Arnaud,
On Tue, 28 Nov 2023 at 13:49, Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> wrote: > > It is not possible to register buffers allocated with vmalloc.
I would rephrase it as:
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@infradead.org> > Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> > --- > > 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@foss.st.com/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@foss.st.com/T/#maca0a1fc897aadd54c7deac432e11473fe970d1d > --- > drivers/tee/tee_shm.c | 77 ++++++++++++++++++++++++------------------- > 1 file changed, 43 insertions(+), 34 deletions(-) > > diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c > index 673cf0359494..fe0a205be7ef 100644 > --- a/drivers/tee/tee_shm.c > +++ b/drivers/tee/tee_shm.c > @@ -22,23 +22,16 @@ 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; > + /* > + * iov_iter_extract_kvec_pages does not get reference on the pages, > + * get a pin on them. > + */ > + 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 +207,13 @@ 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, length, len, off; > void *ret; > int rc; > > @@ -245,31 +238,32 @@ register_shm_helper(struct tee_context *ctx, unsigned long addr, > shm->flags = flags; > shm->ctx = ctx; > shm->id = id; > - addr = untagged_addr(addr); > + addr = (unsigned long)iter_iov_addr(iter);
Why did you drop untagged_addr() here?
> + length = iter_iov_len(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); > + len = iov_iter_extract_pages(iter, &shm->pages, LONG_MAX, num_pages, 0, > + &off); > + if (len != length) {
Any particular reason for this check?
> + ret = len ? ERR_PTR(len) : ERR_PTR(-ENOMEM); > goto err_put_shm_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) { > @@ -307,6 +301,8 @@ 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 iovec iov; > + struct iov_iter iter; > void *ret; > int id; > > @@ -319,7 +315,10 @@ 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.iov_base = (void __user *)addr; > + iov.iov_len = length; > + iov_iter_init(&iter, ITER_DEST, &iov, 1, length);
We should rather use import_ubuf() instead of this and the above access_ok() check.
> + shm = register_shm_helper(ctx, &iter, flags, id); > if (IS_ERR(shm)) { > mutex_lock(&teedev->mutex); > idr_remove(&teedev->idr, id); > @@ -351,9 +350,19 @@ struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx, > struct tee_shm *tee_shm_register_kernel_buf(struct tee_context *ctx, > void *addr, size_t length) > { > + struct tee_shm *shm; > u32 flags = TEE_SHM_DYNAMIC; > + struct kvec kvec; > + struct iov_iter iter; > > - return register_shm_helper(ctx, (unsigned long)addr, length, flags, -1); > + kvec.iov_base = addr; > + kvec.iov_len = length; > + iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, length); > + shm = register_shm_helper(ctx, &iter, flags, -1); > + if (!IS_ERR(shm)) > + shm_get_kernel_pages(shm->pages, shm->num_pages);
The kernel pages reference should be taken before invoking teedev->desc->ops->shm_register(). So you should move this to register_shm_helper() instead. You can use iov_iter_is_kvec() to know if you have to get a reference or not.
-Sumit
> + > + return shm; > } > EXPORT_SYMBOL_GPL(tee_shm_register_kernel_buf); > > -- > 2.25.1 >
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