A potential deadlock fix for SEV and a tiny cleanup

[libvirt] [PATCH 2/2] qemu: sev: Don't jump to endjob if SEV measurement retrieval fails

Posted by Erik Skultety 7 years ago

If measurement retrieval fails we'd forget to call ExitMonitor to unlock
the monitor.

Signed-off-by: Erik Skultety <eskultet@redhat.com>
Reported-by: Luyao Huang <lhuang@redhat.com>
---
 src/qemu/qemu_driver.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index fd25eb1b0b..d71956988f 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -21513,10 +21513,8 @@ qemuDomainGetSEVMeasurement(virQEMUDriverPtr driver,
 
     qemuDomainObjEnterMonitor(driver, vm);
     tmp = qemuMonitorGetSEVMeasurement(QEMU_DOMAIN_PRIVATE(vm)->mon);
-    if (tmp == NULL)
-        goto endjob;
 
-    if (qemuDomainObjExitMonitor(driver, vm) < 0)
+    if (qemuDomainObjExitMonitor(driver, vm) < 0 || !tmp)
         goto endjob;
 
     if (virTypedParamsAddString(params, nparams, &maxpar,
-- 
2.14.4

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Re: [libvirt] [PATCH 2/2] qemu: sev: Don't jump to endjob if SEV measurement retrieval fails

Posted by Marc Hartmayer 7 years ago

On Mon, Jun 18, 2018 at 09:20 AM +0200, Erik Skultety <eskultet@redhat.com> wrote:
> If measurement retrieval fails we'd forget to call ExitMonitor to unlock
> the monitor.
>
> Signed-off-by: Erik Skultety <eskultet@redhat.com>
> Reported-by: Luyao Huang <lhuang@redhat.com>
> ---
>  src/qemu/qemu_driver.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index fd25eb1b0b..d71956988f 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -21513,10 +21513,8 @@ qemuDomainGetSEVMeasurement(virQEMUDriverPtr driver,
>
>      qemuDomainObjEnterMonitor(driver, vm);
>      tmp = qemuMonitorGetSEVMeasurement(QEMU_DOMAIN_PRIVATE(vm)->mon);
> -    if (tmp == NULL)
> -        goto endjob;
>
> -    if (qemuDomainObjExitMonitor(driver, vm) < 0)
> +    if (qemuDomainObjExitMonitor(driver, vm) < 0 || !tmp)
>          goto endjob;
>
>      if (virTypedParamsAddString(params, nparams, &maxpar,
> --
> 2.14.4
>
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Small nit: I would probably just move the “if-tmp-block” behind the
“if-…ExitMonitor()-block”. But I have no strong opinion about that :)

Anyway Reviewed-by: Marc Hartmayer <mhartmay@linux.ibm.com>

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   Marc Hartmayer

IBM Deutschland Research & Development GmbH
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Re: [libvirt] [PATCH 2/2] qemu: sev: Don't jump to endjob if SEV measurement retrieval fails

Posted by Erik Skultety 7 years ago

On Tue, Jun 19, 2018 at 03:52:34PM +0200, Marc Hartmayer wrote:
> On Mon, Jun 18, 2018 at 09:20 AM +0200, Erik Skultety <eskultet@redhat.com> wrote:
> > If measurement retrieval fails we'd forget to call ExitMonitor to unlock
> > the monitor.
> >
> > Signed-off-by: Erik Skultety <eskultet@redhat.com>
> > Reported-by: Luyao Huang <lhuang@redhat.com>
> > ---
> >  src/qemu/qemu_driver.c | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> > index fd25eb1b0b..d71956988f 100644
> > --- a/src/qemu/qemu_driver.c
> > +++ b/src/qemu/qemu_driver.c
> > @@ -21513,10 +21513,8 @@ qemuDomainGetSEVMeasurement(virQEMUDriverPtr driver,
> >
> >      qemuDomainObjEnterMonitor(driver, vm);
> >      tmp = qemuMonitorGetSEVMeasurement(QEMU_DOMAIN_PRIVATE(vm)->mon);
> > -    if (tmp == NULL)
> > -        goto endjob;
> >
> > -    if (qemuDomainObjExitMonitor(driver, vm) < 0)
> > +    if (qemuDomainObjExitMonitor(driver, vm) < 0 || !tmp)
> >          goto endjob;
> >
> >      if (virTypedParamsAddString(params, nparams, &maxpar,
> > --
> > 2.14.4
> >
> > --
> > libvir-list mailing list
> > libvir-list@redhat.com
> > https://www.redhat.com/mailman/listinfo/libvir-list
> >
>
> Small nit: I would probably just move the “if-tmp-block” behind the
> “if-…ExitMonitor()-block”. But I have no strong opinion about that :)

I'll make the change...we should be more consistent here though :).

Thanks,
Erik

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