[Resend] [PATCH] pci-hyperv: use kmalloc to allocate hypercall params buffer

[KY Srinivasan]

> -----Original Message-----
> From: Long Li
> Sent: Tuesday, November 8, 2016 8:57 AM
> To: Greg KH <gregkh at linuxfoundation.org>
> Cc: KY Srinivasan <kys at microsoft.com>; Haiyang Zhang
> <haiyangz at microsoft.com>; Bjorn Helgaas <bhelgaas at google.com>;
> devel at linuxdriverproject.org; linux-kernel at vger.kernel.org; linux-
> pci at vger.kernel.org
> Subject: RE: [Resend] [PATCH] pci-hyperv: use kmalloc to allocate hypercall
> params buffer
> 
> 
> 
> > -----Original Message-----
> > From: Greg KH [mailto:gregkh at linuxfoundation.org]
> > Sent: Monday, November 7, 2016 11:00 PM
> > To: Long Li <longli at microsoft.com>
> > Cc: KY Srinivasan <kys at microsoft.com>; Haiyang Zhang
> > <haiyangz at microsoft.com>; Bjorn Helgaas <bhelgaas at google.com>;
> > devel at linuxdriverproject.org; linux-kernel at vger.kernel.org; linux-
> > pci at vger.kernel.org
> > Subject: Re: [Resend] [PATCH] pci-hyperv: use kmalloc to allocate hypercall
> > params buffer
> >
> > On Tue, Nov 08, 2016 at 12:14:14AM -0800, Long Li wrote:
> > > From: Long Li <longli at microsoft.com>
> > >
> > > hv_do_hypercall assumes that we pass a segment from a physically
> > continuous buffer. Buffer allocated on the stack may not work if
> > CONFIG_VMAP_STACK=y is set. Use kmalloc to allocate this buffer.
> >
> > Please wrap your changelog at 72 columns.

Long, this should not be part of the commit message. Please include changes in
each version below the line (----)

Regards,

K. Y 
> >
> > >
> > > Signed-off-by: Long Li <longli at microsoft.com>
> > > Reported-by: Haiyang Zhang <haiyangz at microsoft.com>
> > > ---
> > >  drivers/pci/host/pci-hyperv.c | 24 +++++++++++++-----------
> > >  1 file changed, 13 insertions(+), 11 deletions(-)
> > >
> > > diff --git a/drivers/pci/host/pci-hyperv.c
> > > b/drivers/pci/host/pci-hyperv.c index 763ff87..97e6daf 100644
> > > --- a/drivers/pci/host/pci-hyperv.c
> > > +++ b/drivers/pci/host/pci-hyperv.c
> > > @@ -378,6 +378,7 @@ struct hv_pcibus_device {
> > >  	struct msi_domain_info msi_info;
> > >  	struct msi_controller msi_chip;
> > >  	struct irq_domain *irq_domain;
> > > +	struct retarget_msi_interrupt retarget_msi_interrupt_params;
> >
> > Can you handle potentially unaligned accesses like this?  Is there some lock
> > preventing you from using this structure more than once at the same time?
> >
> > >  };
> > >
> > >  /*
> > > @@ -774,7 +775,7 @@ void hv_irq_unmask(struct irq_data *data)  {
> > >  	struct msi_desc *msi_desc = irq_data_get_msi_desc(data);
> > >  	struct irq_cfg *cfg = irqd_cfg(data);
> > > -	struct retarget_msi_interrupt params;
> > > +	struct retarget_msi_interrupt *params;
> > >  	struct hv_pcibus_device *hbus;
> > >  	struct cpumask *dest;
> > >  	struct pci_bus *pbus;
> > > @@ -785,23 +786,24 @@ void hv_irq_unmask(struct irq_data *data)
> > >  	pdev = msi_desc_to_pci_dev(msi_desc);
> > >  	pbus = pdev->bus;
> > >  	hbus = container_of(pbus->sysdata, struct hv_pcibus_device,
> > > sysdata);
> > > -
> > > -	memset(&params, 0, sizeof(params));
> > > -	params.partition_id = HV_PARTITION_ID_SELF;
> > > -	params.source = 1; /* MSI(-X) */
> > > -	params.address = msi_desc->msg.address_lo;
> > > -	params.data = msi_desc->msg.data;
> > > -	params.device_id = (hbus->hdev->dev_instance.b[5] << 24) |
> > > +	params = &hbus->retarget_msi_interrupt_params;
> > > +
> > > +	memset(params, 0, sizeof(*params));
> > > +	params->partition_id = HV_PARTITION_ID_SELF;
> > > +	params->source = 1; /* MSI(-X) */
> > > +	params->address = msi_desc->msg.address_lo;
> > > +	params->data = msi_desc->msg.data;
> > > +	params->device_id = (hbus->hdev->dev_instance.b[5] << 24) |
> > >  			   (hbus->hdev->dev_instance.b[4] << 16) |
> > >  			   (hbus->hdev->dev_instance.b[7] << 8) |
> > >  			   (hbus->hdev->dev_instance.b[6] & 0xf8) |
> > >  			   PCI_FUNC(pdev->devfn);
> > > -	params.vector = cfg->vector;
> > > +	params->vector = cfg->vector;
> > >
> > >  	for_each_cpu_and(cpu, dest, cpu_online_mask)
> > > -		params.vp_mask |= (1ULL <<
> > vmbus_cpu_number_to_vp_number(cpu));
> > > +		params->vp_mask |= (1ULL <<
> > vmbus_cpu_number_to_vp_number(cpu));
> > >
> > > -	hv_do_hypercall(HVCALL_RETARGET_INTERRUPT, &params, NULL);
> > > +	hv_do_hypercall(HVCALL_RETARGET_INTERRUPT, params, NULL);
> >
> > As you only use this in one spot, why not just allocate it here and then free
> > it?  Why add it to the pcibus device structure?
> 
> Thanks Greg. I will send a V2.
> 
> >
> > thanks,
> >
> > greg k-h