Re: [Qemu-ppc] [PATCH 2/2] spapr: Simulate CAS for qtest

[Michael Roth]

Quoting Greg Kurz (2019-03-01 13:32:37)
> The RTAS event hotplug code for machine types 2.8 and newer depends on
> the CAS negotiated ov5 in order to work properly. However, there's no
> CAS when running under qtest. There has been a tentative to trick the
> code by faking the OV5_HP_EVT bit, but it turned out to break other
> assumptions in the code and the change got reverted.
> 
> Go for a more general approach and simulate a CAS when running under
> qtest. For simplicity, this pseudo CAS simple simulates the case where
> the guest supports the same features as the machine. It is done at
> reset time, just before we reset the DRCs, which could potentially
> exercise the unplug code.
> 
> This allows to test unplug on spapr with both older and newer machine
> types.
> 
> Suggested-by: Michael Roth <address@hidden>
> Signed-off-by: Greg Kurz <address@hidden>

Tested-by: Michael Roth <address@hidden>
Reviewed-by: Michael Roth <address@hidden>

Thanks for sending this!

Just now realizing we should probably apply the revert after this patch
however, since the commit we're reverting fixes a `make check` test that
is run by default, whereas this patch fixes one that only gets run if we
run the tests with -m=slow specified.

Maybe David can do that on his end?

> ---
>  hw/ppc/spapr.c |   11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index b6a571b6f184..6da64ef7ee2b 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -29,6 +29,7 @@
>  #include "qapi/visitor.h"
>  #include "sysemu/sysemu.h"
>  #include "sysemu/numa.h"
> +#include "sysemu/qtest.h"
>  #include "hw/hw.h"
>  #include "qemu/log.h"
>  #include "hw/fw-path-provider.h"
> @@ -1711,6 +1712,16 @@ static void spapr_machine_reset(void)
>       */
>      spapr_irq_reset(spapr, &error_fatal);
> 
> +    /*
> +     * There is no CAS under qtest. Simulate one to please the code that
> +     * depends on spapr->ov5_cas. This is especially needed to test device
> +     * unplug, so we do that before resetting the DRCs.
> +     */
> +    if (qtest_enabled()) {
> +        spapr_ovec_cleanup(spapr->ov5_cas);
> +        spapr->ov5_cas = spapr_ovec_clone(spapr->ov5);
> +    }
> +
>      /* DRC reset may cause a device to be unplugged. This will cause troubles
>       * if this device is used by another device (eg, a running vhost backend
>       * will crash QEMU if the DIMM holding the vring goes away). To avoid 
> such
>