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Message-ID: <BN3PR03MB2227A432B0288764BA9EE562CEA60@BN3PR03MB2227.namprd03.prod.outlook.com>
Date: Tue, 8 Nov 2016 16:56:31 +0000
From: Long Li <longli@...rosoft.com>
To: Greg KH <gregkh@...uxfoundation.org>
CC: KY Srinivasan <kys@...rosoft.com>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>
Subject: RE: [Resend] [PATCH] pci-hyperv: use kmalloc to allocate hypercall
params buffer
> -----Original Message-----
> From: Greg KH [mailto:gregkh@...uxfoundation.org]
> Sent: Monday, November 7, 2016 11:00 PM
> To: Long Li <longli@...rosoft.com>
> Cc: KY Srinivasan <kys@...rosoft.com>; Haiyang Zhang
> <haiyangz@...rosoft.com>; Bjorn Helgaas <bhelgaas@...gle.com>;
> devel@...uxdriverproject.org; linux-kernel@...r.kernel.org; linux-
> pci@...r.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@...rosoft.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.
>
> >
> > Signed-off-by: Long Li <longli@...rosoft.com>
> > Reported-by: Haiyang Zhang <haiyangz@...rosoft.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(¶ms, 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, ¶ms, 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
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