virtio-ccw: diag 500 may return a negative cookie
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Message ID 20181218132034.14863-1-cohuck@redhat.com
State New
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  • virtio-ccw: diag 500 may return a negative cookie
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Commit Message

Cornelia Huck Dec. 18, 2018, 1:20 p.m. UTC
If something goes wrong in the kvm io bus handling, the virtio-ccw
diagnose may return a negative error value in the cookie gpr.

Document this.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---

Even if the virtio spec is the correct place to specify what diag 500
subcode 3 does, we also should mention here that the cookie may be
an error.

---
 Documentation/virtual/kvm/s390-diag.txt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Halil Pasic Dec. 18, 2018, 1:22 p.m. UTC | #1
On Tue, 18 Dec 2018 14:20:34 +0100
Cornelia Huck <cohuck@redhat.com> wrote:

> If something goes wrong in the kvm io bus handling, the virtio-ccw
> diagnose may return a negative error value in the cookie gpr.
> 
> Document this.
> 
> Signed-off-by: Cornelia Huck <cohuck@redhat.com>

Reviewed-by: Halil Pasic <pasic@linux.ibm.com>

> ---
> 
> Even if the virtio spec is the correct place to specify what diag 500
> subcode 3 does, we also should mention here that the cookie may be
> an error.
> 
> ---
>  Documentation/virtual/kvm/s390-diag.txt | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/virtual/kvm/s390-diag.txt b/Documentation/virtual/kvm/s390-diag.txt
> index 48c4921794ed..7c52e5f8b210 100644
> --- a/Documentation/virtual/kvm/s390-diag.txt
> +++ b/Documentation/virtual/kvm/s390-diag.txt
> @@ -68,7 +68,8 @@ Subcode 3 - virtio-ccw notification
>      identifier, it is ignored.
>  
>      After completion of the DIAGNOSE call, general register 2 may contain
> -    a 64bit identifier (in the kvm_io_bus cookie case).
> +    a 64bit identifier (in the kvm_io_bus cookie case), or a negative
> +    error value, if an internal error occurred.
>  
>      See also the virtio standard for a discussion of this hypercall.
>
Cornelia Huck Dec. 19, 2018, 10:06 a.m. UTC | #2
On Tue, 18 Dec 2018 14:20:34 +0100
Cornelia Huck <cohuck@redhat.com> wrote:

> If something goes wrong in the kvm io bus handling, the virtio-ccw
> diagnose may return a negative error value in the cookie gpr.
> 
> Document this.
> 
> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> ---
> 
> Even if the virtio spec is the correct place to specify what diag 500
> subcode 3 does, we also should mention here that the cookie may be
> an error.
> 
> ---
>  Documentation/virtual/kvm/s390-diag.txt | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/virtual/kvm/s390-diag.txt b/Documentation/virtual/kvm/s390-diag.txt
> index 48c4921794ed..7c52e5f8b210 100644
> --- a/Documentation/virtual/kvm/s390-diag.txt
> +++ b/Documentation/virtual/kvm/s390-diag.txt
> @@ -68,7 +68,8 @@ Subcode 3 - virtio-ccw notification
>      identifier, it is ignored.
>  
>      After completion of the DIAGNOSE call, general register 2 may contain
> -    a 64bit identifier (in the kvm_io_bus cookie case).
> +    a 64bit identifier (in the kvm_io_bus cookie case), or a negative
> +    error value, if an internal error occurred.
>  
>      See also the virtio standard for a discussion of this hypercall.
>  

Queued.

Patch
diff mbox series

diff --git a/Documentation/virtual/kvm/s390-diag.txt b/Documentation/virtual/kvm/s390-diag.txt
index 48c4921794ed..7c52e5f8b210 100644
--- a/Documentation/virtual/kvm/s390-diag.txt
+++ b/Documentation/virtual/kvm/s390-diag.txt
@@ -68,7 +68,8 @@  Subcode 3 - virtio-ccw notification
     identifier, it is ignored.
 
     After completion of the DIAGNOSE call, general register 2 may contain
-    a 64bit identifier (in the kvm_io_bus cookie case).
+    a 64bit identifier (in the kvm_io_bus cookie case), or a negative
+    error value, if an internal error occurred.
 
     See also the virtio standard for a discussion of this hypercall.