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Re: [Qemu-ppc] [PATCH v6 01/11] machine: Don't allow CPU toplogies with
From: |
Bharata B Rao |
Subject: |
Re: [Qemu-ppc] [PATCH v6 01/11] machine: Don't allow CPU toplogies with partially filled cores |
Date: |
Mon, 25 Jan 2016 14:27:25 +0530 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Sat, Jan 23, 2016 at 11:47:22AM -0200, Eduardo Habkost wrote:
> On Fri, Jan 08, 2016 at 12:25:09PM +0530, Bharata B Rao wrote:
> > Prevent guests from booting with CPU topologies that have partially
> > filled CPU cores or can result in partially filled CPU cores after
> > CPU hotplug like
> >
> > -smp 15,sockets=1,cores=4,threads=4,maxcpus=16 or
> > -smp 15,sockets=1,cores=4,threads=4,maxcpus=17.
> >
> > This is enforced by introducing MachineClass::validate_smp_config()
> > that gets called from generic SMP parsing code. Machine type versions
> > that don't want to enforce this can override this method.
> >
> > TODO: Only sPAPR and PC changes are done in this patch, other archs
> > will be touched after there is agreement on this approach.
> >
> > Signed-off-by: Bharata B Rao <address@hidden>
> > ---
> > hw/core/machine.c | 20 ++++++++++++++++++++
> > hw/i386/pc_piix.c | 7 +++++++
> > hw/i386/pc_q35.c | 7 +++++++
> > hw/ppc/spapr.c | 7 +++++++
> > include/hw/boards.h | 1 +
> > vl.c | 4 ++++
> > 6 files changed, 46 insertions(+)
> >
> > diff --git a/hw/core/machine.c b/hw/core/machine.c
> > index c46ddc7..b66c101 100644
> > --- a/hw/core/machine.c
> > +++ b/hw/core/machine.c
> > @@ -336,6 +336,25 @@ static void machine_init_notify(Notifier *notifier,
> > void *data)
> > foreach_dynamic_sysbus_device(error_on_sysbus_device, NULL);
> > }
> >
> > +static int validate_smp_config_generic(int smp_cpus, int max_cpus,
> > + int smp_threads)
>
> Please make it use a Error** parameter to return error
> information, and let the caller decide what to do with the error
> message. One day the mc->validate_smp_config() call may be moved
> inside a function that returns error information using Error**
> and needs to propagate it to the caller.
Sure, will make this change.
I see that not all target archs use machine type versions and even
if they do it will not be a one-line changer (as shown for i386 and sPAPR in
this patch) for them to override mc->validate_smp_config() for older
versions.
So am I expected to change .class_init routine for all these archs by
setting mc->validate_smp_config() to a NOP validate_smp_config()
so that the default validate_smp_config() defined for TYPE_MACHINE
is overridden ? In order to preserve the existing behaviour with
CPU topology for all args, it appears that such a change would be
necessary, but I am not sure how to test all of them. Will just a compile
test do ?
Regards,
Bharata.