[PATCH v2] tee: convert convert get_user_pages() --> pin_user_pages()

[PATCH v2] tee: convert convert get_user_pages() --> pin_user_pages()

[John Hubbard]

This code was using get_user_pages*(), in a "Case 2" scenario
(DMA/RDMA), using the categorization from [1]. That means that it's
time to convert the get_user_pages*() + put_page() calls to
pin_user_pages*() + unpin_user_pages() calls.

There is some helpful background in [2]: basically, this is a small
part of fixing a long-standing disconnect between pinning pages, and
file systems' use of those pages.

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
    https://lwn.net/Articles/807108/

Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: tee-dev@lists.linaro.org
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---

OK, this should be indentical to v1 [1], but now rebased against
Linux 5.9-rc2.

As before, I've compile-tested it again with a cross compiler, but that's
the only testing I'm set up for with CONFIG_TEE.

[1] https://lore.kernel.org/r/20200519051850.2845561-1-jhubbard@nvidia.com

thanks,
John Hubbard
NVIDIA

 drivers/tee/tee_shm.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index 827ac3d0fea9..3c29e6c3ebe8 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -32,16 +32,13 @@ static void tee_shm_release(struct tee_shm *shm)
 
 		poolm->ops->free(poolm, shm);
 	} else if (shm->flags & TEE_SHM_REGISTER) {
-		size_t n;
 		int rc = teedev->desc->ops->shm_unregister(shm->ctx, shm);
 
 		if (rc)
 			dev_err(teedev->dev.parent,
 				"unregister shm %p failed: %d", shm, rc);
 
-		for (n = 0; n < shm->num_pages; n++)
-			put_page(shm->pages[n]);
-
+		unpin_user_pages(shm->pages, shm->num_pages);
 		kfree(shm->pages);
 	}
 
@@ -228,7 +225,7 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
 	}
 
 	if (flags & TEE_SHM_USER_MAPPED) {
-		rc = get_user_pages_fast(start, num_pages, FOLL_WRITE,
+		rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE,
 					 shm->pages);
 	} else {
 		struct kvec *kiov;
@@ -292,16 +289,13 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
 	return shm;
 err:
 	if (shm) {
-		size_t n;
-
 		if (shm->id >= 0) {
 			mutex_lock(&teedev->mutex);
 			idr_remove(&teedev->idr, shm->id);
 			mutex_unlock(&teedev->mutex);
 		}
 		if (shm->pages) {
-			for (n = 0; n < shm->num_pages; n++)
-				put_page(shm->pages[n]);
+			unpin_user_pages(shm->pages, shm->num_pages);
 			kfree(shm->pages);
 		}
 	}
-- 
2.28.0

Re: [PATCH v2] tee: convert convert get_user_pages() --> pin_user_pages()

[John Hubbard]

On 8/24/20 11:36 AM, John Hubbard wrote:
> This code was using get_user_pages*(), in a "Case 2" scenario
> (DMA/RDMA), using the categorization from [1]. That means that it's
> time to convert the get_user_pages*() + put_page() calls to
> pin_user_pages*() + unpin_user_pages() calls.
> 
> There is some helpful background in [2]: basically, this is a small
> part of fixing a long-standing disconnect between pinning pages, and
> file systems' use of those pages.
> 
> [1] Documentation/core-api/pin_user_pages.rst
> 
> [2] "Explicit pinning of user-space pages":
>      https://lwn.net/Articles/807108/
> 
> Cc: Jens Wiklander <jens.wiklander@linaro.org>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: tee-dev@lists.linaro.org
> Cc: linux-media@vger.kernel.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: linaro-mm-sig@lists.linaro.org
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> ---
> 
> OK, this should be indentical to v1 [1], but now rebased against
> Linux 5.9-rc2.
> 

...ohhh, wait, I should have read the earlier message from Jens more
carefully:

"The conflict isn't trivial, I guess we need to handle the different
types of pages differently when releasing them."

So it's not good to have a logically identical patch. argghhh. Let me see
how hard it is to track these memory types separately and handle the release
accordingly, just a sec.

Sorry about the false move here.

thanks,
-- 
John Hubbard
NVIDIA

> As before, I've compile-tested it again with a cross compiler, but that's
> the only testing I'm set up for with CONFIG_TEE.
> 
> [1] https://lore.kernel.org/r/20200519051850.2845561-1-jhubbard@nvidia.com
> 
> thanks,
> John Hubbard
> NVIDIA
> 
>   drivers/tee/tee_shm.c | 12 +++---------
>   1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 827ac3d0fea9..3c29e6c3ebe8 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -32,16 +32,13 @@ static void tee_shm_release(struct tee_shm *shm)
>   
>   		poolm->ops->free(poolm, shm);
>   	} else if (shm->flags & TEE_SHM_REGISTER) {
> -		size_t n;
>   		int rc = teedev->desc->ops->shm_unregister(shm->ctx, shm);
>   
>   		if (rc)
>   			dev_err(teedev->dev.parent,
>   				"unregister shm %p failed: %d", shm, rc);
>   
> -		for (n = 0; n < shm->num_pages; n++)
> -			put_page(shm->pages[n]);
> -
> +		unpin_user_pages(shm->pages, shm->num_pages);
>   		kfree(shm->pages);
>   	}
>   
> @@ -228,7 +225,7 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
>   	}
>   
>   	if (flags & TEE_SHM_USER_MAPPED) {
> -		rc = get_user_pages_fast(start, num_pages, FOLL_WRITE,
> +		rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE,
>   					 shm->pages);
>   	} else {
>   		struct kvec *kiov;
> @@ -292,16 +289,13 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
>   	return shm;
>   err:
>   	if (shm) {
> -		size_t n;
> -
>   		if (shm->id >= 0) {
>   			mutex_lock(&teedev->mutex);
>   			idr_remove(&teedev->idr, shm->id);
>   			mutex_unlock(&teedev->mutex);
>   		}
>   		if (shm->pages) {
> -			for (n = 0; n < shm->num_pages; n++)
> -				put_page(shm->pages[n]);
> +			unpin_user_pages(shm->pages, shm->num_pages);
>   			kfree(shm->pages);
>   		}
>   	}
> 

v

[PATCH v3] tee: convert convert get_user_pages() --> pin_user_pages()

[John Hubbard]

This code was using get_user_pages*(), in a "Case 2" scenario
(DMA/RDMA), using the categorization from [1]. That means that it's
time to convert the get_user_pages*() + put_page() calls to
pin_user_pages*() + unpin_user_pages() calls.

Factor out a new, small release_registered_pages() function, in
order to consolidate the logic for discerning between
TEE_SHM_USER_MAPPED and TEE_SHM_KERNEL_MAPPED pages. This also
absorbs the kfree() call that is also required there.

There is some helpful background in [2]: basically, this is a small
part of fixing a long-standing disconnect between pinning pages, and
file systems' use of those pages.

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
    https://lwn.net/Articles/807108/

Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: tee-dev@lists.linaro.org
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---

OK, one more try, this time actually handling the _USER_MAPPED vs.
_KERNEL_MAPPED pages!

thanks,
John Hubbard
NVIDIA

 drivers/tee/tee_shm.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index 827ac3d0fea9..00472f5ce22e 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -12,6 +12,22 @@
 #include <linux/uio.h>
 #include "tee_private.h"
 
+static void release_registered_pages(struct tee_shm *shm)
+{
+	if (shm->pages) {
+		if (shm->flags & TEE_SHM_USER_MAPPED) {
+			unpin_user_pages(shm->pages, shm->num_pages);
+		} else {
+			size_t n;
+
+			for (n = 0; n < shm->num_pages; n++)
+				put_page(shm->pages[n]);
+		}
+
+		kfree(shm->pages);
+	}
+}
+
 static void tee_shm_release(struct tee_shm *shm)
 {
 	struct tee_device *teedev = shm->ctx->teedev;
@@ -32,17 +48,13 @@ static void tee_shm_release(struct tee_shm *shm)
 
 		poolm->ops->free(poolm, shm);
 	} else if (shm->flags & TEE_SHM_REGISTER) {
-		size_t n;
 		int rc = teedev->desc->ops->shm_unregister(shm->ctx, shm);
 
 		if (rc)
 			dev_err(teedev->dev.parent,
 				"unregister shm %p failed: %d", shm, rc);
 
-		for (n = 0; n < shm->num_pages; n++)
-			put_page(shm->pages[n]);
-
-		kfree(shm->pages);
+		release_registered_pages(shm);
 	}
 
 	teedev_ctx_put(shm->ctx);
@@ -228,7 +240,7 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
 	}
 
 	if (flags & TEE_SHM_USER_MAPPED) {
-		rc = get_user_pages_fast(start, num_pages, FOLL_WRITE,
+		rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE,
 					 shm->pages);
 	} else {
 		struct kvec *kiov;
@@ -292,18 +304,12 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
 	return shm;
 err:
 	if (shm) {
-		size_t n;
-
 		if (shm->id >= 0) {
 			mutex_lock(&teedev->mutex);
 			idr_remove(&teedev->idr, shm->id);
 			mutex_unlock(&teedev->mutex);
 		}
-		if (shm->pages) {
-			for (n = 0; n < shm->num_pages; n++)
-				put_page(shm->pages[n]);
-			kfree(shm->pages);
-		}
+		release_registered_pages(shm);
 	}
 	kfree(shm);
 	teedev_ctx_put(ctx);
-- 
2.28.0

Re: [PATCH v3] tee: convert convert get_user_pages() --> pin_user_pages()

[Jens Wiklander]

On Mon, Aug 24, 2020 at 02:11:25PM -0700, John Hubbard wrote:
> This code was using get_user_pages*(), in a "Case 2" scenario
> (DMA/RDMA), using the categorization from [1]. That means that it's
> time to convert the get_user_pages*() + put_page() calls to
> pin_user_pages*() + unpin_user_pages() calls.
> 
> Factor out a new, small release_registered_pages() function, in
> order to consolidate the logic for discerning between
> TEE_SHM_USER_MAPPED and TEE_SHM_KERNEL_MAPPED pages. This also
> absorbs the kfree() call that is also required there.
> 
> There is some helpful background in [2]: basically, this is a small
> part of fixing a long-standing disconnect between pinning pages, and
> file systems' use of those pages.
> 
> [1] Documentation/core-api/pin_user_pages.rst
> 
> [2] "Explicit pinning of user-space pages":
>     https://lwn.net/Articles/807108/
> 
> Cc: Jens Wiklander <jens.wiklander@linaro.org>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: tee-dev@lists.linaro.org
> Cc: linux-media@vger.kernel.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: linaro-mm-sig@lists.linaro.org
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> ---
> 
> OK, one more try, this time actually handling the _USER_MAPPED vs.
> _KERNEL_MAPPED pages!
> 
> thanks,
> John Hubbard
> NVIDIA

Looks good and it works too! :-) I've tested it on my Hikey board with
the OP-TEE test suite.
I'm picking this up.

Thanks,
Jens

Re: [PATCH v3] tee: convert convert get_user_pages() --> pin_user_pages()

[John Hubbard]

On 8/25/20 1:32 AM, Jens Wiklander wrote:
> On Mon, Aug 24, 2020 at 02:11:25PM -0700, John Hubbard wrote:
...
>> OK, one more try, this time actually handling the _USER_MAPPED vs.
>> _KERNEL_MAPPED pages!
>>
>> thanks,
>> John Hubbard
>> NVIDIA
> 
> Looks good and it works too! :-) I've tested it on my Hikey board with
> the OP-TEE test suite.
> I'm picking this up.
> 

Great! I see that I have, once again, somehow doubled up on the subject line:
"tee: convert convert ...". This particular typo just seems to stick to me. :)

If you get a chance to fix that up by changing it to just a single "convert"
I'd appreciate it.

thanks,
-- 
John Hubbard
NVIDIA

Re: [PATCH v3] tee: convert convert get_user_pages() --> pin_user_pages()

[Jens Wiklander]

On Tue, Aug 25, 2020 at 10:54 AM John Hubbard <jhubbard@nvidia.com> wrote:
>
> On 8/25/20 1:32 AM, Jens Wiklander wrote:
> > On Mon, Aug 24, 2020 at 02:11:25PM -0700, John Hubbard wrote:
> ...
> >> OK, one more try, this time actually handling the _USER_MAPPED vs.
> >> _KERNEL_MAPPED pages!
> >>
> >> thanks,
> >> John Hubbard
> >> NVIDIA
> >
> > Looks good and it works too! :-) I've tested it on my Hikey board with
> > the OP-TEE test suite.
> > I'm picking this up.
> >
>
> Great! I see that I have, once again, somehow doubled up on the subject line:
> "tee: convert convert ...". This particular typo just seems to stick to me. :)
>
> If you get a chance to fix that up by changing it to just a single "convert"
> I'd appreciate it.

Sure, no problem.

Cheers,
Jens