[Qemu-devel] [PULL for-2.1 0/3] virtio-scsi fixes, and block/iscsi compilation fix

[Qemu-devel] [PULL for-2.1 0/3] virtio-scsi fixes, and block/iscsi compilation fix

[Paolo Bonzini]

The following changes since commit ec9fe956d5c728da770db5ec9bc429080ccb5043:

  Merge remote-tracking branch 'remotes/bonzini/small-fixes' into staging (2014-06-30 15:56:00 +0100)

are available in the git repository at:


  git://github.com/bonzini/qemu.git scsi-next

for you to fetch changes up to 5da65870fb1f698aab8c265c55884ca3d955276b:

  configure: Fix -lm test, so that tools can be compiled on hosts that require -lm (2014-07-01 09:42:59 +0200)

----------------------------------------------------------------
Alexey Kardashevskiy (1):
      configure: Fix -lm test, so that tools can be compiled on hosts that require -lm

Cédric Le Goater (1):
      virtio-scsi: scsi events must be converted to target endianness

Greg Kurz (1):
      virtio-scsi: virtio_scsi_push_event() lacks VirtIOSCSIReq parsing

 Makefile.target       |  4 ----
 configure             |  2 +-
 hw/scsi/virtio-scsi.c | 12 +++---------
 3 files changed, 4 insertions(+), 14 deletions(-)
-- 
1.8.3.1

[Qemu-devel] [PULL 1/3] virtio-scsi: virtio_scsi_push_event() lacks VirtIOSCSIReq parsing

[Paolo Bonzini]

From: Greg Kurz <gkurz@linux.vnet.ibm.com>

Hotplug of a virtio scsi disk is currently broken: no disk appears in the
guest (verified with a fedora 20 host running a fedora 20 guest with KVM).
Bisect leeds to Paolo's patches to support any_layout, especially this
commit:

commit 36b15c79aa1bef5fe7543f9f2629b6413720bbfb
Author: Paolo Bonzini <pbonzini@redhat.com>
Date:   Tue Jun 10 16:21:18 2014 +0200

    virtio-scsi: start preparing for any_layout

It modifies virtio_scsi_pop_req() so that it is up to the callers to parse
the virtio scsi request. It seems that virtio_scsi_push_event() was not
modified accordingly...

This patch adds a call to virtio_scsi_parse_req(). It also drops some
sanity checks that are already performed by virtio_scsi_parse_req().

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/scsi/virtio-scsi.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 04ecfa7..3fecdca 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -565,7 +565,6 @@ static void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev,
     VirtIOSCSIReq *req;
     VirtIOSCSIEvent *evt;
     VirtIODevice *vdev = VIRTIO_DEVICE(s);
-    int in_size;
 
     if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
         return;
@@ -577,17 +576,12 @@ static void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev,
         return;
     }
 
-    if (req->elem.out_num) {
-        virtio_scsi_bad_req();
-    }
-
     if (s->events_dropped) {
         event |= VIRTIO_SCSI_T_EVENTS_MISSED;
         s->events_dropped = false;
     }
 
-    in_size = iov_size(req->elem.in_sg, req->elem.in_num);
-    if (in_size < sizeof(VirtIOSCSIEvent)) {
+    if (virtio_scsi_parse_req(req, 0, sizeof(VirtIOSCSIEvent))) {
         virtio_scsi_bad_req();
     }
 
-- 
1.8.3.1

[Qemu-devel] [PULL 2/3] virtio-scsi: scsi events must be converted to target endianness

[Paolo Bonzini]

From: Cédric Le Goater <clg@fr.ibm.com>

Virtio SCSI Events need to be byteswapped before being pushed
when host and guest have a different endianness. Not doing so
breaks hotplug of virtio scsi disks, with the following error
message being printed in the guest console:

virtio_scsi: Unsupport virtio scsi event 1000000

This issue got uncovered while testing disk hotplug with a PowerKVM
ppc64le guest. I have checked that this issue also affects a x86_64
guest run on a ppc64 host.

Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
[ Ported from PowerKVM,
  Greg Kurz <gkurz@linux.vnet.ibm.com> ]
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/scsi/virtio-scsi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 3fecdca..0eb069a 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -587,8 +587,8 @@ static void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev,
 
     evt = &req->resp.event;
     memset(evt, 0, sizeof(VirtIOSCSIEvent));
-    evt->event = event;
-    evt->reason = reason;
+    evt->event = virtio_tswap32(vdev, event);
+    evt->reason = virtio_tswap32(vdev, reason);
     if (!dev) {
         assert(event == VIRTIO_SCSI_T_EVENTS_MISSED);
     } else {
-- 
1.8.3.1

[Qemu-devel] [PULL 3/3] configure: Fix -lm test, so that tools can be compiled on hosts that require -lm

[Paolo Bonzini]

From: Alexey Kardashevskiy <aik@ozlabs.ru>

The existing test whether "-lm" needs to be included or not is
insufficient as it reports false negative on Fedora20/ppc64.
This happens because sin(0.0) is a constant value which compiler
can safely throw away and therefore there is no need to add "-lm".
As the result, qemu-nbd/qemu-io/qemu-img tools cannot compile.

This adds a global variable and uses it in the test to prevent
from optimization.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
[Remove now useless -lm addition in Makefile.target. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 Makefile.target | 4 ----
 configure       | 2 +-
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/Makefile.target b/Makefile.target
index 6089d29..137d0b0 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -163,10 +163,6 @@ dummy := $(call unnest-vars,.., \
 all-obj-y += $(common-obj-y)
 all-obj-$(CONFIG_SOFTMMU) += $(block-obj-y)
 
-ifndef CONFIG_HAIKU
-LIBS+=-lm
-endif
-
 # build either PROG or PROGW
 $(QEMU_PROG_BUILD): $(all-obj-y) ../libqemuutil.a ../libqemustub.a
 	$(call LINK,$^)
diff --git a/configure b/configure
index 23ecb37..6dd44a9 100755
--- a/configure
+++ b/configure
@@ -3453,7 +3453,7 @@ fi
 # Do we need libm
 cat > $TMPC << EOF
 #include <math.h>
-int main(void) { return isnan(sin(0.0)); }
+double x; int main(void) {return isnan(sin(x));}
 EOF
 if compile_prog "" "" ; then
   :
-- 
1.8.3.1

Re: [Qemu-devel] [PULL 3/3] configure: Fix -lm test, so that tools can be compiled on hosts that require -lm

[Peter Maydell]

On 1 July 2014 09:22, Paolo Bonzini <pbonzini@redhat.com> wrote:
> From: Alexey Kardashevskiy <aik@ozlabs.ru>
>
> The existing test whether "-lm" needs to be included or not is
> insufficient as it reports false negative on Fedora20/ppc64.
> This happens because sin(0.0) is a constant value which compiler
> can safely throw away and therefore there is no need to add "-lm".
> As the result, qemu-nbd/qemu-io/qemu-img tools cannot compile.
>
> This adds a global variable and uses it in the test to prevent
> from optimization.

> --- a/configure
> +++ b/configure
> @@ -3453,7 +3453,7 @@ fi
>  # Do we need libm
>  cat > $TMPC << EOF
>  #include <math.h>
> -int main(void) { return isnan(sin(0.0)); }
> +double x; int main(void) {return isnan(sin(x));}
>  EOF
>  if compile_prog "" "" ; then
>    :

This looks to me like we're leaving ourselves open for
a smarter compiler with linktime optimisation to complain
that x is used uninitialized.

thanks
-- PMM

Re: [Qemu-devel] [PULL 3/3] configure: Fix -lm test, so that tools can be compiled on hosts that require -lm

[Eric Blake]

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On 07/01/2014 02:26 AM, Peter Maydell wrote:
> On 1 July 2014 09:22, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> From: Alexey Kardashevskiy <aik@ozlabs.ru>
>>
>> The existing test whether "-lm" needs to be included or not is
>> insufficient as it reports false negative on Fedora20/ppc64.
>> This happens because sin(0.0) is a constant value which compiler
>> can safely throw away and therefore there is no need to add "-lm".
>> As the result, qemu-nbd/qemu-io/qemu-img tools cannot compile.
>>
>> This adds a global variable and uses it in the test to prevent
>> from optimization.
> 
>> --- a/configure
>> +++ b/configure
>> @@ -3453,7 +3453,7 @@ fi
>>  # Do we need libm
>>  cat > $TMPC << EOF
>>  #include <math.h>
>> -int main(void) { return isnan(sin(0.0)); }
>> +double x; int main(void) {return isnan(sin(x));}
>>  EOF
>>  if compile_prog "" "" ; then
>>    :
> 
> This looks to me like we're leaving ourselves open for
> a smarter compiler with linktime optimisation to complain
> that x is used uninitialized.

If that's your worry, what about:

int main(int argc, char **argv) { return isnan(sin(argc > 1)); }

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PULL 3/3] configure: Fix -lm test, so that tools can be compiled on hosts that require -lm

[Markus Armbruster]

Peter Maydell <peter.maydell@linaro.org> writes:

> On 1 July 2014 09:22, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> From: Alexey Kardashevskiy <aik@ozlabs.ru>
>>
>> The existing test whether "-lm" needs to be included or not is
>> insufficient as it reports false negative on Fedora20/ppc64.
>> This happens because sin(0.0) is a constant value which compiler
>> can safely throw away and therefore there is no need to add "-lm".
>> As the result, qemu-nbd/qemu-io/qemu-img tools cannot compile.
>>
>> This adds a global variable and uses it in the test to prevent
>> from optimization.
>
>> --- a/configure
>> +++ b/configure
>> @@ -3453,7 +3453,7 @@ fi
>>  # Do we need libm
>>  cat > $TMPC << EOF
>>  #include <math.h>
>> -int main(void) { return isnan(sin(0.0)); }
>> +double x; int main(void) {return isnan(sin(x));}
>>  EOF
>>  if compile_prog "" "" ; then
>>    :
>
> This looks to me like we're leaving ourselves open for
> a smarter compiler with linktime optimisation to complain
> that x is used uninitialized.

x *is* initialized, to zero.  A sufficiently smart compiler(TM) could
figure out that x is still zero in main(), and constant fold the test
away.

Suggest to use argc.

Re: [Qemu-devel] [PULL 3/3] configure: Fix -lm test, so that tools can be compiled on hosts that require -lm

[Peter Maydell]

On 2 July 2014 08:02, Markus Armbruster <armbru@redhat.com> wrote:
>> This looks to me like we're leaving ourselves open for
>> a smarter compiler with linktime optimisation to complain
>> that x is used uninitialized.
>
> x *is* initialized, to zero.  A sufficiently smart compiler(TM) could
> figure out that x is still zero in main(), and constant fold the test
> away.

Yes, I was wrong there.

> Suggest to use argc.

That's what we did -- see commit f80ea986.

thanks
-- PMM