[PATCH 0/1] s390/uv: fix for ultravisor query function

[PATCH 0/1] s390/uv: fix for ultravisor query function

[Christian Borntraeger]

As outlined by the architects the query command could actually return more
than the minimal 168 bytes.

I will carry this with the KVM host support for protected virtualization

Christian Borntraeger (1):
  s390/uv: Fix handling of length extensions

 arch/s390/boot/uv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.24.0

[PATCH 1/1] s390/uv: Fix handling of length extensions

[Christian Borntraeger]

The query parameter block might contain additional information and can
be extended in the future. If the size of the block does not suffice we
get an error code of rc=0x100.  The buffer will contain all information
up to the specified size and the hypervisor/guest simply do not need the
additional information as they do not know about the new data.  That
means that we can (and must) accept rc=0x100 as success.

Cc: stable@vger.kernel.org
Fixes: 5abb9351dfd9 ("s390/uv: introduce guest side ultravisor code")
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 arch/s390/boot/uv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/boot/uv.c b/arch/s390/boot/uv.c
index af9e1cc93c68..c003593664cd 100644
--- a/arch/s390/boot/uv.c
+++ b/arch/s390/boot/uv.c
@@ -21,7 +21,7 @@ void uv_query_info(void)
 	if (!test_facility(158))
 		return;
 
-	if (uv_call(0, (uint64_t)&uvcb))
+	if (uv_call(0, (uint64_t)&uvcb) && uvcb.header.rc != 0x100)
 		return;
 
 	if (IS_ENABLED(CONFIG_KVM)) {
-- 
2.24.0

Re: [PATCH 1/1] s390/uv: Fix handling of length extensions

[Cornelia Huck]

On Mon, 10 Feb 2020 11:54:39 -0500
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> The query parameter block might contain additional information and can
> be extended in the future. If the size of the block does not suffice we
> get an error code of rc=0x100.  The buffer will contain all information
> up to the specified size and the hypervisor/guest simply do not need the
> additional information as they do not know about the new data.  That
> means that we can (and must) accept rc=0x100 as success.
> 
> Cc: stable@vger.kernel.org
> Fixes: 5abb9351dfd9 ("s390/uv: introduce guest side ultravisor code")
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/boot/uv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/s390/boot/uv.c b/arch/s390/boot/uv.c
> index af9e1cc93c68..c003593664cd 100644
> --- a/arch/s390/boot/uv.c
> +++ b/arch/s390/boot/uv.c
> @@ -21,7 +21,7 @@ void uv_query_info(void)
>  	if (!test_facility(158))
>  		return;
>  
> -	if (uv_call(0, (uint64_t)&uvcb))
> +	if (uv_call(0, (uint64_t)&uvcb) && uvcb.header.rc != 0x100)

Add a comment like

/* rc==0x100 means that there is additional data we do not process */

to avoid headscratching in the future?

>  		return;
>  
>  	if (IS_ENABLED(CONFIG_KVM)) {

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

Re: [PATCH 1/1] s390/uv: Fix handling of length extensions

[Christian Borntraeger]

On 10.02.20 18:31, Cornelia Huck wrote:
> On Mon, 10 Feb 2020 11:54:39 -0500
> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> 
>> The query parameter block might contain additional information and can
>> be extended in the future. If the size of the block does not suffice we
>> get an error code of rc=0x100.  The buffer will contain all information
>> up to the specified size and the hypervisor/guest simply do not need the
>> additional information as they do not know about the new data.  That
>> means that we can (and must) accept rc=0x100 as success.
>>
>> Cc: stable@vger.kernel.org
>> Fixes: 5abb9351dfd9 ("s390/uv: introduce guest side ultravisor code")
>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> ---
>>  arch/s390/boot/uv.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/boot/uv.c b/arch/s390/boot/uv.c
>> index af9e1cc93c68..c003593664cd 100644
>> --- a/arch/s390/boot/uv.c
>> +++ b/arch/s390/boot/uv.c
>> @@ -21,7 +21,7 @@ void uv_query_info(void)
>>  	if (!test_facility(158))
>>  		return;
>>  
>> -	if (uv_call(0, (uint64_t)&uvcb))
>> +	if (uv_call(0, (uint64_t)&uvcb) && uvcb.header.rc != 0x100)
> 
> Add a comment like
> 
> /* rc==0x100 means that there is additional data we do not process */

ack.

> 
> to avoid headscratching in the future?
> 
>>  		return;
>>  
>>  	if (IS_ENABLED(CONFIG_KVM)) {
> 
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> 

Re: [PATCH 1/1] s390/uv: Fix handling of length extensions

[Janosch Frank]

[-- Attachment #1.1: Type: text/plain, Size: 1288 bytes --]

On 2/10/20 5:54 PM, Christian Borntraeger wrote:
> The query parameter block might contain additional information and can
> be extended in the future. If the size of the block does not suffice we
> get an error code of rc=0x100.  The buffer will contain all information
> up to the specified size and the hypervisor/guest simply do not need the
> additional information as they do not know about the new data.  That
                                                                ^

> means that we can (and must) accept rc=0x100 as success.

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

> 
> Cc: stable@vger.kernel.org
> Fixes: 5abb9351dfd9 ("s390/uv: introduce guest side ultravisor code")
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/boot/uv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/s390/boot/uv.c b/arch/s390/boot/uv.c
> index af9e1cc93c68..c003593664cd 100644
> --- a/arch/s390/boot/uv.c
> +++ b/arch/s390/boot/uv.c
> @@ -21,7 +21,7 @@ void uv_query_info(void)
>  	if (!test_facility(158))
>  		return;
> 
> -	if (uv_call(0, (uint64_t)&uvcb))
> +	if (uv_call(0, (uint64_t)&uvcb) && uvcb.header.rc != 0x100)
>  		return;
> 
>  	if (IS_ENABLED(CONFIG_KVM)) {
> 



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Re: [PATCH 0/1] s390/uv: fix for ultravisor query function

[Cornelia Huck]

On Mon, 10 Feb 2020 11:54:38 -0500
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> As outlined by the architects the query command could actually return more
> than the minimal 168 bytes.
> 
> I will carry this with the KVM host support for protected virtualization

As this is cc:stable (and also relevant for the guest side), why not
merge it right now?

> 
> Christian Borntraeger (1):
>   s390/uv: Fix handling of length extensions
> 
>  arch/s390/boot/uv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Re: [PATCH 0/1] s390/uv: fix for ultravisor query function

[Christian Borntraeger]

On 10.02.20 18:32, Cornelia Huck wrote:
> On Mon, 10 Feb 2020 11:54:38 -0500
> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> 
>> As outlined by the architects the query command could actually return more
>> than the minimal 168 bytes.
>>
>> I will carry this with the KVM host support for protected virtualization
> 
> As this is cc:stable (and also relevant for the guest side), why not
> merge it right now?
> 
Agreed. Will do.

>>
>> Christian Borntraeger (1):
>>   s390/uv: Fix handling of length extensions
>>
>>  arch/s390/boot/uv.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
> 

Re: [PATCH 0/1] s390/uv: fix for ultravisor query function

[Christian Borntraeger]

On 10.02.20 18:35, Christian Borntraeger wrote:
> 
> 
> On 10.02.20 18:32, Cornelia Huck wrote:
>> On Mon, 10 Feb 2020 11:54:38 -0500
>> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
>>
>>> As outlined by the architects the query command could actually return more
>>> than the minimal 168 bytes.
>>>
>>> I will carry this with the KVM host support for protected virtualization
>>
>> As this is cc:stable (and also relevant for the guest side), why not
>> merge it right now?
>>
> Agreed. Will do.

Pushed to the internal tree. If nobody comes up with a reason not to, Vasily
will have this in his next pull request for Linux.