* [PATCH] vhost: use bvec_kmap_local in {get,put}u16_iotlb
@ 2022-02-22 15:48 ` Christoph Hellwig
0 siblings, 0 replies; 4+ messages in thread
From: Christoph Hellwig @ 2022-02-22 15:48 UTC (permalink / raw)
To: jasowang; +Cc: kvm, virtualization
Using local kmaps slightly reduces the chances to stray writes, and
the bvec interface cleans up the code a little bit.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/vhost/vringh.c | 18 ++++++++----------
1 file changed, 8 insertions(+), 10 deletions(-)
diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
index 14e2043d76852..0f22a83fd09af 100644
--- a/drivers/vhost/vringh.c
+++ b/drivers/vhost/vringh.c
@@ -1173,7 +1173,7 @@ static inline int getu16_iotlb(const struct vringh *vrh,
u16 *val, const __virtio16 *p)
{
struct bio_vec iov;
- void *kaddr, *from;
+ void *kaddr;
int ret;
/* Atomic read is needed for getu16 */
@@ -1182,10 +1182,9 @@ static inline int getu16_iotlb(const struct vringh *vrh,
if (ret < 0)
return ret;
- kaddr = kmap_atomic(iov.bv_page);
- from = kaddr + iov.bv_offset;
- *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)from));
- kunmap_atomic(kaddr);
+ kaddr = bvec_kmap_local(&iov);
+ *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)kaddr));
+ kunmap_local(kaddr);
return 0;
}
@@ -1194,7 +1193,7 @@ static inline int putu16_iotlb(const struct vringh *vrh,
__virtio16 *p, u16 val)
{
struct bio_vec iov;
- void *kaddr, *to;
+ void *kaddr;
int ret;
/* Atomic write is needed for putu16 */
@@ -1203,10 +1202,9 @@ static inline int putu16_iotlb(const struct vringh *vrh,
if (ret < 0)
return ret;
- kaddr = kmap_atomic(iov.bv_page);
- to = kaddr + iov.bv_offset;
- WRITE_ONCE(*(__virtio16 *)to, cpu_to_vringh16(vrh, val));
- kunmap_atomic(kaddr);
+ kaddr = bvec_kmap_local(&iov);
+ WRITE_ONCE(*(__virtio16 *)kaddr, cpu_to_vringh16(vrh, val));
+ kunmap_local(kaddr);
return 0;
}
--
2.30.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH] vhost: use bvec_kmap_local in {get,put}u16_iotlb
@ 2022-02-22 15:48 ` Christoph Hellwig
0 siblings, 0 replies; 4+ messages in thread
From: Christoph Hellwig @ 2022-02-22 15:48 UTC (permalink / raw)
To: jasowang; +Cc: kvm, virtualization
Using local kmaps slightly reduces the chances to stray writes, and
the bvec interface cleans up the code a little bit.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/vhost/vringh.c | 18 ++++++++----------
1 file changed, 8 insertions(+), 10 deletions(-)
diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
index 14e2043d76852..0f22a83fd09af 100644
--- a/drivers/vhost/vringh.c
+++ b/drivers/vhost/vringh.c
@@ -1173,7 +1173,7 @@ static inline int getu16_iotlb(const struct vringh *vrh,
u16 *val, const __virtio16 *p)
{
struct bio_vec iov;
- void *kaddr, *from;
+ void *kaddr;
int ret;
/* Atomic read is needed for getu16 */
@@ -1182,10 +1182,9 @@ static inline int getu16_iotlb(const struct vringh *vrh,
if (ret < 0)
return ret;
- kaddr = kmap_atomic(iov.bv_page);
- from = kaddr + iov.bv_offset;
- *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)from));
- kunmap_atomic(kaddr);
+ kaddr = bvec_kmap_local(&iov);
+ *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)kaddr));
+ kunmap_local(kaddr);
return 0;
}
@@ -1194,7 +1193,7 @@ static inline int putu16_iotlb(const struct vringh *vrh,
__virtio16 *p, u16 val)
{
struct bio_vec iov;
- void *kaddr, *to;
+ void *kaddr;
int ret;
/* Atomic write is needed for putu16 */
@@ -1203,10 +1202,9 @@ static inline int putu16_iotlb(const struct vringh *vrh,
if (ret < 0)
return ret;
- kaddr = kmap_atomic(iov.bv_page);
- to = kaddr + iov.bv_offset;
- WRITE_ONCE(*(__virtio16 *)to, cpu_to_vringh16(vrh, val));
- kunmap_atomic(kaddr);
+ kaddr = bvec_kmap_local(&iov);
+ WRITE_ONCE(*(__virtio16 *)kaddr, cpu_to_vringh16(vrh, val));
+ kunmap_local(kaddr);
return 0;
}
--
2.30.2
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Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] vhost: use bvec_kmap_local in {get,put}u16_iotlb
2022-02-22 15:48 ` Christoph Hellwig
@ 2022-02-23 2:18 ` Jason Wang
-1 siblings, 0 replies; 4+ messages in thread
From: Jason Wang @ 2022-02-23 2:18 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: kvm, virtualization
On Tue, Feb 22, 2022 at 11:49 PM Christoph Hellwig <hch@lst.de> wrote:
>
> Using local kmaps slightly reduces the chances to stray writes, and
> the bvec interface cleans up the code a little bit.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jason Wang <jasowang@redhat.com>
> ---
> drivers/vhost/vringh.c | 18 ++++++++----------
> 1 file changed, 8 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
> index 14e2043d76852..0f22a83fd09af 100644
> --- a/drivers/vhost/vringh.c
> +++ b/drivers/vhost/vringh.c
> @@ -1173,7 +1173,7 @@ static inline int getu16_iotlb(const struct vringh *vrh,
> u16 *val, const __virtio16 *p)
> {
> struct bio_vec iov;
> - void *kaddr, *from;
> + void *kaddr;
> int ret;
>
> /* Atomic read is needed for getu16 */
> @@ -1182,10 +1182,9 @@ static inline int getu16_iotlb(const struct vringh *vrh,
> if (ret < 0)
> return ret;
>
> - kaddr = kmap_atomic(iov.bv_page);
> - from = kaddr + iov.bv_offset;
> - *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)from));
> - kunmap_atomic(kaddr);
> + kaddr = bvec_kmap_local(&iov);
> + *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)kaddr));
> + kunmap_local(kaddr);
>
> return 0;
> }
> @@ -1194,7 +1193,7 @@ static inline int putu16_iotlb(const struct vringh *vrh,
> __virtio16 *p, u16 val)
> {
> struct bio_vec iov;
> - void *kaddr, *to;
> + void *kaddr;
> int ret;
>
> /* Atomic write is needed for putu16 */
> @@ -1203,10 +1202,9 @@ static inline int putu16_iotlb(const struct vringh *vrh,
> if (ret < 0)
> return ret;
>
> - kaddr = kmap_atomic(iov.bv_page);
> - to = kaddr + iov.bv_offset;
> - WRITE_ONCE(*(__virtio16 *)to, cpu_to_vringh16(vrh, val));
> - kunmap_atomic(kaddr);
> + kaddr = bvec_kmap_local(&iov);
> + WRITE_ONCE(*(__virtio16 *)kaddr, cpu_to_vringh16(vrh, val));
> + kunmap_local(kaddr);
>
> return 0;
> }
> --
> 2.30.2
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] vhost: use bvec_kmap_local in {get,put}u16_iotlb
@ 2022-02-23 2:18 ` Jason Wang
0 siblings, 0 replies; 4+ messages in thread
From: Jason Wang @ 2022-02-23 2:18 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: kvm, virtualization
On Tue, Feb 22, 2022 at 11:49 PM Christoph Hellwig <hch@lst.de> wrote:
>
> Using local kmaps slightly reduces the chances to stray writes, and
> the bvec interface cleans up the code a little bit.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jason Wang <jasowang@redhat.com>
> ---
> drivers/vhost/vringh.c | 18 ++++++++----------
> 1 file changed, 8 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
> index 14e2043d76852..0f22a83fd09af 100644
> --- a/drivers/vhost/vringh.c
> +++ b/drivers/vhost/vringh.c
> @@ -1173,7 +1173,7 @@ static inline int getu16_iotlb(const struct vringh *vrh,
> u16 *val, const __virtio16 *p)
> {
> struct bio_vec iov;
> - void *kaddr, *from;
> + void *kaddr;
> int ret;
>
> /* Atomic read is needed for getu16 */
> @@ -1182,10 +1182,9 @@ static inline int getu16_iotlb(const struct vringh *vrh,
> if (ret < 0)
> return ret;
>
> - kaddr = kmap_atomic(iov.bv_page);
> - from = kaddr + iov.bv_offset;
> - *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)from));
> - kunmap_atomic(kaddr);
> + kaddr = bvec_kmap_local(&iov);
> + *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)kaddr));
> + kunmap_local(kaddr);
>
> return 0;
> }
> @@ -1194,7 +1193,7 @@ static inline int putu16_iotlb(const struct vringh *vrh,
> __virtio16 *p, u16 val)
> {
> struct bio_vec iov;
> - void *kaddr, *to;
> + void *kaddr;
> int ret;
>
> /* Atomic write is needed for putu16 */
> @@ -1203,10 +1202,9 @@ static inline int putu16_iotlb(const struct vringh *vrh,
> if (ret < 0)
> return ret;
>
> - kaddr = kmap_atomic(iov.bv_page);
> - to = kaddr + iov.bv_offset;
> - WRITE_ONCE(*(__virtio16 *)to, cpu_to_vringh16(vrh, val));
> - kunmap_atomic(kaddr);
> + kaddr = bvec_kmap_local(&iov);
> + WRITE_ONCE(*(__virtio16 *)kaddr, cpu_to_vringh16(vrh, val));
> + kunmap_local(kaddr);
>
> return 0;
> }
> --
> 2.30.2
>
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-02-23 2:18 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2022-02-22 15:48 [PATCH] vhost: use bvec_kmap_local in {get,put}u16_iotlb Christoph Hellwig
2022-02-22 15:48 ` Christoph Hellwig
2022-02-23 2:18 ` Jason Wang
2022-02-23 2:18 ` Jason Wang
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