[PATCH v3 0/3] Few bug fixes and Convert to pin_user_pages*()

[PATCH v3 0/3] Few bug fixes and Convert to pin_user_pages*()

[Souptick Joarder]

This series contains few clean up, minor bug fixes and
Convert get_user_pages() to pin_user_pages().

I'm compile tested this, but unable to run-time test,
so any testing help is much appriciated.

v2:
        Addressed few review comments and compile issue.
        Patch[1/2] from v1 split into 2 in v2.
v3:
	Address review comment. Add review tag.

Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Paul Durrant <xadimgnik@gmail.com>

Souptick Joarder (3):
  xen/privcmd: Corrected error handling path
  xen/privcmd: Mark pages as dirty
  xen/privcmd: Convert get_user_pages*() to pin_user_pages*()

 drivers/xen/privcmd.c | 32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)

-- 
1.9.1

[PATCH v3 1/3] xen/privcmd: Corrected error handling path

[Souptick Joarder]

Previously, if lock_pages() end up partially mapping pages, it used
to return -ERRNO due to which unlock_pages() have to go through
each pages[i] till *nr_pages* to validate them. This can be avoided
by passing correct number of partially mapped pages & -ERRNO separately,
while returning from lock_pages() due to error.

With this fix unlock_pages() doesn't need to validate pages[i] till
*nr_pages* for error scenario and few condition checks can be ignored.

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Paul Durrant <xadimgnik@gmail.com>
---
 drivers/xen/privcmd.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 5dfc59f..b001673 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -579,13 +579,13 @@ static long privcmd_ioctl_mmap_batch(
 
 static int lock_pages(
 	struct privcmd_dm_op_buf kbufs[], unsigned int num,
-	struct page *pages[], unsigned int nr_pages)
+	struct page *pages[], unsigned int nr_pages, unsigned int *pinned)
 {
 	unsigned int i;
 
 	for (i = 0; i < num; i++) {
 		unsigned int requested;
-		int pinned;
+		int page_count;
 
 		requested = DIV_ROUND_UP(
 			offset_in_page(kbufs[i].uptr) + kbufs[i].size,
@@ -593,14 +593,15 @@ static int lock_pages(
 		if (requested > nr_pages)
 			return -ENOSPC;
 
-		pinned = get_user_pages_fast(
+		page_count = get_user_pages_fast(
 			(unsigned long) kbufs[i].uptr,
 			requested, FOLL_WRITE, pages);
-		if (pinned < 0)
-			return pinned;
+		if (page_count < 0)
+			return page_count;
 
-		nr_pages -= pinned;
-		pages += pinned;
+		*pinned += page_count;
+		nr_pages -= page_count;
+		pages += page_count;
 	}
 
 	return 0;
@@ -610,13 +611,8 @@ static void unlock_pages(struct page *pages[], unsigned int nr_pages)
 {
 	unsigned int i;
 
-	if (!pages)
-		return;
-
-	for (i = 0; i < nr_pages; i++) {
-		if (pages[i])
-			put_page(pages[i]);
-	}
+	for (i = 0; i < nr_pages; i++)
+		put_page(pages[i]);
 }
 
 static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
@@ -629,6 +625,7 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
 	struct xen_dm_op_buf *xbufs = NULL;
 	unsigned int i;
 	long rc;
+	unsigned int pinned = 0;
 
 	if (copy_from_user(&kdata, udata, sizeof(kdata)))
 		return -EFAULT;
@@ -682,9 +679,11 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
 		goto out;
 	}
 
-	rc = lock_pages(kbufs, kdata.num, pages, nr_pages);
-	if (rc)
+	rc = lock_pages(kbufs, kdata.num, pages, nr_pages, &pinned);
+	if (rc < 0) {
+		nr_pages = pinned;
 		goto out;
+	}
 
 	for (i = 0; i < kdata.num; i++) {
 		set_xen_guest_handle(xbufs[i].h, kbufs[i].uptr);
-- 
1.9.1

[PATCH v3 2/3] xen/privcmd: Mark pages as dirty

[Souptick Joarder]

pages need to be marked as dirty before unpinned it in
unlock_pages() which was oversight. This is fixed now.

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Suggested-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Paul Durrant <xadimgnik@gmail.com>
---
 drivers/xen/privcmd.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index b001673..079d35b 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -611,8 +611,11 @@ static void unlock_pages(struct page *pages[], unsigned int nr_pages)
 {
 	unsigned int i;
 
-	for (i = 0; i < nr_pages; i++)
+	for (i = 0; i < nr_pages; i++) {
+		if (!PageDirty(pages[i]))
+			set_page_dirty_lock(pages[i]);
 		put_page(pages[i]);
+	}
 }
 
 static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
-- 
1.9.1

[PATCH v3 3/3] xen/privcmd: Convert get_user_pages*() to pin_user_pages*()

[Souptick Joarder]

In 2019, we introduced pin_user_pages*() and now we are converting
get_user_pages*() to the new API as appropriate. [1] & [2] could
be referred for more information. This is case 5 as per document [1].

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

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

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Paul Durrant <xadimgnik@gmail.com>
---
 drivers/xen/privcmd.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 079d35b..63abe6c 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -593,7 +593,7 @@ static int lock_pages(
 		if (requested > nr_pages)
 			return -ENOSPC;
 
-		page_count = get_user_pages_fast(
+		page_count = pin_user_pages_fast(
 			(unsigned long) kbufs[i].uptr,
 			requested, FOLL_WRITE, pages);
 		if (page_count < 0)
@@ -609,13 +609,7 @@ static int lock_pages(
 
 static void unlock_pages(struct page *pages[], unsigned int nr_pages)
 {
-	unsigned int i;
-
-	for (i = 0; i < nr_pages; i++) {
-		if (!PageDirty(pages[i]))
-			set_page_dirty_lock(pages[i]);
-		put_page(pages[i]);
-	}
+	unpin_user_pages_dirty_lock(pages, nr_pages, true);
 }
 
 static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
-- 
1.9.1

RE: [PATCH v3 1/3] xen/privcmd: Corrected error handling path

[Paul Durrant]

> -----Original Message-----
> From: Souptick Joarder <jrdr.linux@gmail.com>
> Sent: 12 July 2020 04:40
> To: boris.ostrovsky@oracle.com; jgross@suse.com; sstabellini@kernel.org
> Cc: xen-devel@lists.xenproject.org; linux-kernel@vger.kernel.org; Souptick Joarder
> <jrdr.linux@gmail.com>; John Hubbard <jhubbard@nvidia.com>; Paul Durrant <xadimgnik@gmail.com>
> Subject: [PATCH v3 1/3] xen/privcmd: Corrected error handling path
> 
> Previously, if lock_pages() end up partially mapping pages, it used
> to return -ERRNO due to which unlock_pages() have to go through
> each pages[i] till *nr_pages* to validate them. This can be avoided
> by passing correct number of partially mapped pages & -ERRNO separately,
> while returning from lock_pages() due to error.
> 
> With this fix unlock_pages() doesn't need to validate pages[i] till
> *nr_pages* for error scenario and few condition checks can be ignored.
> 
> Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> Reviewed-by: Juergen Gross <jgross@suse.com>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Paul Durrant <xadimgnik@gmail.com>

Reviewed-by: Paul Durrant <paul@xen.org>

> ---
>  drivers/xen/privcmd.c | 31 +++++++++++++++----------------
>  1 file changed, 15 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 5dfc59f..b001673 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -579,13 +579,13 @@ static long privcmd_ioctl_mmap_batch(
> 
>  static int lock_pages(
>  	struct privcmd_dm_op_buf kbufs[], unsigned int num,
> -	struct page *pages[], unsigned int nr_pages)
> +	struct page *pages[], unsigned int nr_pages, unsigned int *pinned)
>  {
>  	unsigned int i;
> 
>  	for (i = 0; i < num; i++) {
>  		unsigned int requested;
> -		int pinned;
> +		int page_count;
> 
>  		requested = DIV_ROUND_UP(
>  			offset_in_page(kbufs[i].uptr) + kbufs[i].size,
> @@ -593,14 +593,15 @@ static int lock_pages(
>  		if (requested > nr_pages)
>  			return -ENOSPC;
> 
> -		pinned = get_user_pages_fast(
> +		page_count = get_user_pages_fast(
>  			(unsigned long) kbufs[i].uptr,
>  			requested, FOLL_WRITE, pages);
> -		if (pinned < 0)
> -			return pinned;
> +		if (page_count < 0)
> +			return page_count;
> 
> -		nr_pages -= pinned;
> -		pages += pinned;
> +		*pinned += page_count;
> +		nr_pages -= page_count;
> +		pages += page_count;
>  	}
> 
>  	return 0;
> @@ -610,13 +611,8 @@ static void unlock_pages(struct page *pages[], unsigned int nr_pages)
>  {
>  	unsigned int i;
> 
> -	if (!pages)
> -		return;
> -
> -	for (i = 0; i < nr_pages; i++) {
> -		if (pages[i])
> -			put_page(pages[i]);
> -	}
> +	for (i = 0; i < nr_pages; i++)
> +		put_page(pages[i]);
>  }
> 
>  static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
> @@ -629,6 +625,7 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
>  	struct xen_dm_op_buf *xbufs = NULL;
>  	unsigned int i;
>  	long rc;
> +	unsigned int pinned = 0;
> 
>  	if (copy_from_user(&kdata, udata, sizeof(kdata)))
>  		return -EFAULT;
> @@ -682,9 +679,11 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
>  		goto out;
>  	}
> 
> -	rc = lock_pages(kbufs, kdata.num, pages, nr_pages);
> -	if (rc)
> +	rc = lock_pages(kbufs, kdata.num, pages, nr_pages, &pinned);
> +	if (rc < 0) {
> +		nr_pages = pinned;
>  		goto out;
> +	}
> 
>  	for (i = 0; i < kdata.num; i++) {
>  		set_xen_guest_handle(xbufs[i].h, kbufs[i].uptr);
> --
> 1.9.1

RE: [PATCH v3 2/3] xen/privcmd: Mark pages as dirty

[Paul Durrant]

> -----Original Message-----
> From: Souptick Joarder <jrdr.linux@gmail.com>
> Sent: 12 July 2020 04:40
> To: boris.ostrovsky@oracle.com; jgross@suse.com; sstabellini@kernel.org
> Cc: xen-devel@lists.xenproject.org; linux-kernel@vger.kernel.org; Souptick Joarder
> <jrdr.linux@gmail.com>; John Hubbard <jhubbard@nvidia.com>; Paul Durrant <xadimgnik@gmail.com>
> Subject: [PATCH v3 2/3] xen/privcmd: Mark pages as dirty
> 
> pages need to be marked as dirty before unpinned it in
> unlock_pages() which was oversight. This is fixed now.
> 
> Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> Suggested-by: John Hubbard <jhubbard@nvidia.com>
> Reviewed-by: Juergen Gross <jgross@suse.com>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Paul Durrant <xadimgnik@gmail.com>

Reviewed-by: Paul Durrant <paul@xen.org>

> ---
>  drivers/xen/privcmd.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index b001673..079d35b 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -611,8 +611,11 @@ static void unlock_pages(struct page *pages[], unsigned int nr_pages)
>  {
>  	unsigned int i;
> 
> -	for (i = 0; i < nr_pages; i++)
> +	for (i = 0; i < nr_pages; i++) {
> +		if (!PageDirty(pages[i]))
> +			set_page_dirty_lock(pages[i]);
>  		put_page(pages[i]);
> +	}
>  }
> 
>  static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
> --
> 1.9.1

RE: [PATCH v3 3/3] xen/privcmd: Convert get_user_pages*() to pin_user_pages*()

[Paul Durrant]

> -----Original Message-----
> From: Souptick Joarder <jrdr.linux@gmail.com>
> Sent: 12 July 2020 04:40
> To: boris.ostrovsky@oracle.com; jgross@suse.com; sstabellini@kernel.org
> Cc: xen-devel@lists.xenproject.org; linux-kernel@vger.kernel.org; Souptick Joarder
> <jrdr.linux@gmail.com>; John Hubbard <jhubbard@nvidia.com>; Paul Durrant <xadimgnik@gmail.com>
> Subject: [PATCH v3 3/3] xen/privcmd: Convert get_user_pages*() to pin_user_pages*()
> 
> In 2019, we introduced pin_user_pages*() and now we are converting
> get_user_pages*() to the new API as appropriate. [1] & [2] could
> be referred for more information. This is case 5 as per document [1].
> 
> [1] Documentation/core-api/pin_user_pages.rst
> 
> [2] "Explicit pinning of user-space pages":
>         https://lwn.net/Articles/807108/
> 
> Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> Reviewed-by: Juergen Gross <jgross@suse.com>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Paul Durrant <xadimgnik@gmail.com>

Reviewed-by: Paul Durrant <paul@xen.org>

> ---
>  drivers/xen/privcmd.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 079d35b..63abe6c 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -593,7 +593,7 @@ static int lock_pages(
>  		if (requested > nr_pages)
>  			return -ENOSPC;
> 
> -		page_count = get_user_pages_fast(
> +		page_count = pin_user_pages_fast(
>  			(unsigned long) kbufs[i].uptr,
>  			requested, FOLL_WRITE, pages);
>  		if (page_count < 0)
> @@ -609,13 +609,7 @@ static int lock_pages(
> 
>  static void unlock_pages(struct page *pages[], unsigned int nr_pages)
>  {
> -	unsigned int i;
> -
> -	for (i = 0; i < nr_pages; i++) {
> -		if (!PageDirty(pages[i]))
> -			set_page_dirty_lock(pages[i]);
> -		put_page(pages[i]);
> -	}
> +	unpin_user_pages_dirty_lock(pages, nr_pages, true);
>  }
> 
>  static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
> --
> 1.9.1

Re: [PATCH v3 0/3] Few bug fixes and Convert to pin_user_pages*()

[Souptick Joarder]

Hi Boris,

On Sun, Jul 12, 2020 at 9:01 AM Souptick Joarder <jrdr.linux@gmail.com> wrote:
>
> This series contains few clean up, minor bug fixes and
> Convert get_user_pages() to pin_user_pages().
>
> I'm compile tested this, but unable to run-time test,
> so any testing help is much appriciated.
>
> v2:
>         Addressed few review comments and compile issue.
>         Patch[1/2] from v1 split into 2 in v2.
> v3:
>         Address review comment. Add review tag.
>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Paul Durrant <xadimgnik@gmail.com>
>
> Souptick Joarder (3):
>   xen/privcmd: Corrected error handling path
>   xen/privcmd: Mark pages as dirty
>   xen/privcmd: Convert get_user_pages*() to pin_user_pages*()

Does this series looks good to go for 5.9 ?

>
>  drivers/xen/privcmd.c | 32 ++++++++++++++------------------
>  1 file changed, 14 insertions(+), 18 deletions(-)
>
> --
> 1.9.1
>

Re: [PATCH v3 0/3] Few bug fixes and Convert to pin_user_pages*()

[Jürgen Groß]

On 28.07.20 09:10, Souptick Joarder wrote:
> Hi Boris,
> 
> On Sun, Jul 12, 2020 at 9:01 AM Souptick Joarder <jrdr.linux@gmail.com> wrote:
>>
>> This series contains few clean up, minor bug fixes and
>> Convert get_user_pages() to pin_user_pages().
>>
>> I'm compile tested this, but unable to run-time test,
>> so any testing help is much appriciated.
>>
>> v2:
>>          Addressed few review comments and compile issue.
>>          Patch[1/2] from v1 split into 2 in v2.
>> v3:
>>          Address review comment. Add review tag.
>>
>> Cc: John Hubbard <jhubbard@nvidia.com>
>> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>> Cc: Paul Durrant <xadimgnik@gmail.com>
>>
>> Souptick Joarder (3):
>>    xen/privcmd: Corrected error handling path
>>    xen/privcmd: Mark pages as dirty
>>    xen/privcmd: Convert get_user_pages*() to pin_user_pages*()
> 
> Does this series looks good to go for 5.9 ?

Yes. I already have it in my queue.


Juergen

Re: [PATCH v3 0/3] Few bug fixes and Convert to pin_user_pages*()

[Jürgen Groß]

On 12.07.20 05:39, Souptick Joarder wrote:
> This series contains few clean up, minor bug fixes and
> Convert get_user_pages() to pin_user_pages().
> 
> I'm compile tested this, but unable to run-time test,
> so any testing help is much appriciated.
> 
> v2:
>          Addressed few review comments and compile issue.
>          Patch[1/2] from v1 split into 2 in v2.
> v3:
> 	Address review comment. Add review tag.
> 
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Paul Durrant <xadimgnik@gmail.com>
> 
> Souptick Joarder (3):
>    xen/privcmd: Corrected error handling path
>    xen/privcmd: Mark pages as dirty
>    xen/privcmd: Convert get_user_pages*() to pin_user_pages*()
> 
>   drivers/xen/privcmd.c | 32 ++++++++++++++------------------
>   1 file changed, 14 insertions(+), 18 deletions(-)
> 

Series pushed to xen/tip.git for-linus-5.9


Juergen