[Qemu-devel] [PATCH v2] scsi-disk: Don't enlarge min_io_size to max_io_size

[Qemu-devel] [PATCH v2] scsi-disk: Don't enlarge min_io_size to max_io_size

[Fam Zheng]

Some backends report big max_io_sectors. Making min_io_size the same
value in this case will make it impossible for guest to align memory,
therefore the disk may not be usable at all.

Do not enlarge them when they are zero.

Reported-by: David Gibson <dgibson@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>

---

v2: Leave the values alone if zero. [Paolo]
    At least we can consult block layer for a slightly more sensible
    opt_io_size, but that's for another patch.
---
 hw/scsi/scsi-disk.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index f5ab767ab5..f8ed8cf2b4 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -714,10 +714,12 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf)
 
                 /* min_io_size and opt_io_size can't be greater than
                  * max_io_sectors */
-                min_io_size =
-                    MIN_NON_ZERO(min_io_size, max_io_sectors);
-                opt_io_size =
-                    MIN_NON_ZERO(opt_io_size, max_io_sectors);
+                if (min_io_size) {
+                    min_io_size = MIN(min_io_size, max_io_sectors);
+                }
+                if (opt_io_size) {
+                    opt_io_size = MIN(opt_io_size, max_io_sectors);
+                }
             }
             /* required VPD size with unmap support */
             buflen = 0x40;
-- 
2.14.3

Re: [Qemu-devel] [PATCH v2] scsi-disk: Don't enlarge min_io_size to max_io_size

[Daniel Henrique Barboza]

On 03/27/2018 01:41 PM, Fam Zheng wrote:
> Some backends report big max_io_sectors. Making min_io_size the same
> value in this case will make it impossible for guest to align memory,
> therefore the disk may not be usable at all.
>
> Do not enlarge them when they are zero.
>
> Reported-by: David Gibson <dgibson@redhat.com>
> Signed-off-by: Fam Zheng <famz@redhat.com>
>
> ---
>
> v2: Leave the values alone if zero. [Paolo]
>      At least we can consult block layer for a slightly more sensible
>      opt_io_size, but that's for another patch.
> ---
>   hw/scsi/scsi-disk.c | 10 ++++++----
>   1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index f5ab767ab5..f8ed8cf2b4 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -714,10 +714,12 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf)
>
>                   /* min_io_size and opt_io_size can't be greater than
>                    * max_io_sectors */
> -                min_io_size =
> -                    MIN_NON_ZERO(min_io_size, max_io_sectors);
> -                opt_io_size =
> -                    MIN_NON_ZERO(opt_io_size, max_io_sectors);
> +                if (min_io_size) {
> +                    min_io_size = MIN(min_io_size, max_io_sectors);
> +                }
> +                if (opt_io_size) {
> +                    opt_io_size = MIN(opt_io_size, max_io_sectors);
> +                }
>               }
>               /* required VPD size with unmap support */
>               buflen = 0x40;

Reviewed-by: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>

Re: [Qemu-devel] [PATCH v2] scsi-disk: Don't enlarge min_io_size to max_io_size

[David Gibson]

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On Wed, Mar 28, 2018 at 12:41:41AM +0800, Fam Zheng wrote:
> Some backends report big max_io_sectors. Making min_io_size the same
> value in this case will make it impossible for guest to align memory,
> therefore the disk may not be usable at all.
> 
> Do not enlarge them when they are zero.
> 
> Reported-by: David Gibson <dgibson@redhat.com>
> Signed-off-by: Fam Zheng <famz@redhat.com>

Tested-by: David Gibson <david@gibson.dropbear.id.au>

With this patch applied, I was able to successfully install a ppc64le
guest again.

> 
> ---
> 
> v2: Leave the values alone if zero. [Paolo]
>     At least we can consult block layer for a slightly more sensible
>     opt_io_size, but that's for another patch.
> ---
>  hw/scsi/scsi-disk.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index f5ab767ab5..f8ed8cf2b4 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -714,10 +714,12 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf)
>  
>                  /* min_io_size and opt_io_size can't be greater than
>                   * max_io_sectors */
> -                min_io_size =
> -                    MIN_NON_ZERO(min_io_size, max_io_sectors);
> -                opt_io_size =
> -                    MIN_NON_ZERO(opt_io_size, max_io_sectors);
> +                if (min_io_size) {
> +                    min_io_size = MIN(min_io_size, max_io_sectors);
> +                }
> +                if (opt_io_size) {
> +                    opt_io_size = MIN(opt_io_size, max_io_sectors);
> +                }
>              }
>              /* required VPD size with unmap support */
>              buflen = 0x40;

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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Re: [Qemu-devel] [PATCH v2] scsi-disk: Don't enlarge min_io_size to max_io_size

[Paolo Bonzini]

On 27/03/2018 18:41, Fam Zheng wrote:
> Some backends report big max_io_sectors. Making min_io_size the same
> value in this case will make it impossible for guest to align memory,
> therefore the disk may not be usable at all.
> 
> Do not enlarge them when they are zero.
> 
> Reported-by: David Gibson <dgibson@redhat.com>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> 
> ---
> 
> v2: Leave the values alone if zero. [Paolo]
>     At least we can consult block layer for a slightly more sensible
>     opt_io_size, but that's for another patch.
> ---
>  hw/scsi/scsi-disk.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index f5ab767ab5..f8ed8cf2b4 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -714,10 +714,12 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf)
>  
>                  /* min_io_size and opt_io_size can't be greater than
>                   * max_io_sectors */
> -                min_io_size =
> -                    MIN_NON_ZERO(min_io_size, max_io_sectors);
> -                opt_io_size =
> -                    MIN_NON_ZERO(opt_io_size, max_io_sectors);
> +                if (min_io_size) {
> +                    min_io_size = MIN(min_io_size, max_io_sectors);
> +                }
> +                if (opt_io_size) {
> +                    opt_io_size = MIN(opt_io_size, max_io_sectors);
> +                }
>              }
>              /* required VPD size with unmap support */
>              buflen = 0x40;
> 

Queued, thanks.

Paolo

Re: [Qemu-devel] [PATCH v2] scsi-disk: Don't enlarge min_io_size to max_io_size

[David Gibson]

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On Thu, 5 Apr 2018 17:54:00 +0200
Paolo Bonzini <pbonzini@redhat.com> wrote:

> On 27/03/2018 18:41, Fam Zheng wrote:
> > Some backends report big max_io_sectors. Making min_io_size the same
> > value in this case will make it impossible for guest to align memory,
> > therefore the disk may not be usable at all.
> > 
> > Do not enlarge them when they are zero.
> > 
> > Reported-by: David Gibson <dgibson@redhat.com>
> > Signed-off-by: Fam Zheng <famz@redhat.com>
[snip]
> Queued, thanks.
> 
> Paolo

Any ETA on going from queued to actually merged?  This is holding up a
handful of Power bugfixes for 2.12, because I can't complete my usual
testing cycle.

-- 
David Gibson <dgibson@redhat.com>
Principal Software Engineer, Virtualization, Red Hat

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Re: [Qemu-devel] [PATCH v2] scsi-disk: Don't enlarge min_io_size to max_io_size

[Paolo Bonzini]

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On 09/04/2018 03:08, David Gibson wrote:
> On Thu, 5 Apr 2018 17:54:00 +0200 Paolo Bonzini <pbonzini@redhat.com> wrote:
>> On 27/03/2018 18:41, Fam Zheng wrote:
>>> Some backends report big max_io_sectors. Making min_io_size the same
>>> value in this case will make it impossible for guest to align memory,
>>> therefore the disk may not be usable at all.
>>>
>>> Do not enlarge them when they are zero.
>>
>> Queued, thanks.
>>
>> Paolo
> 
> Any ETA on going from queued to actually merged?  This is holding up a
> handful of Power bugfixes for 2.12, because I can't complete my usual
> testing cycle.

Hi David,

it's already included in my pull request from Friday.

Paolo


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Re: [Qemu-devel] [PATCH v2] scsi-disk: Don't enlarge min_io_size to max_io_size

[David Gibson]

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On Mon, 9 Apr 2018 11:28:16 +0200
Paolo Bonzini <pbonzini@redhat.com> wrote:

> On 09/04/2018 03:08, David Gibson wrote:
>  [...]  
>  [...]  
>  [...]  
>  [...]  
>  [...]  
> 
> Hi David,
> 
> it's already included in my pull request from Friday.

And I see it in master now.  Thanks!

-- 
David Gibson <dgibson@redhat.com>
Principal Software Engineer, Virtualization, Red Hat

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