Re: [Xen-devel] [PATCH 05/13] Xen: ARM: Add support for mapping platform device mmio

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Nov 17, 2015 at 05:57:03PM +0800, shannon.zhao@xxxxxxxxxx wrote:
> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> 
> Add a bus_notifier for platform bus device in order to map the device
> mmio regions when DOM0 booting with ACPI.
> 
> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> ---
>  drivers/xen/Makefile   |   1 +
>  drivers/xen/platform.c | 104 
> +++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 105 insertions(+)
>  create mode 100644 drivers/xen/platform.c
> 
> diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
> index e293bc5..2f867e7 100644
> --- a/drivers/xen/Makefile
> +++ b/drivers/xen/Makefile
> @@ -11,6 +11,7 @@ CFLAGS_features.o                   := $(nostackp)
>  
>  CFLAGS_efi.o                         += -fshort-wchar
>  
> +dom0-$(CONFIG_ARM64) += platform.o
>  dom0-$(CONFIG_PCI) += pci.o
>  dom0-$(CONFIG_USB_SUPPORT) += dbgp.o
>  dom0-$(CONFIG_XEN_ACPI) += acpi.o $(xen-pad-y)
> diff --git a/drivers/xen/platform.c b/drivers/xen/platform.c
> new file mode 100644
> index 0000000..0f95e7f
> --- /dev/null
> +++ b/drivers/xen/platform.c
> @@ -0,0 +1,104 @@
> +/*
> + * Copyright (c) 2015, Linaro Limited.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along 
> with
> + * this program; if not, write to the Free Software Foundation, Inc., 59 
> Temple
> + * Place - Suite 330, Boston, MA 02111-1307 USA.
> + *
> + * Author: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> + */
> +
> +#include <linux/platform_device.h>
> +#include <linux/acpi.h>
> +#include <xen/xen.h>
> +#include <xen/interface/memory.h>
> +#include <asm/xen/hypervisor.h>
> +#include <asm/xen/hypercall.h>
> +
> +static int xen_map_platform_device_mmio(struct platform_device *pdev)
> +{
> +     int i, rc = 0;

unsigned int i;
> +
> +     for (i = 0; i < pdev->num_resources; i++)
> +     {
> +             struct resource *r = &pdev->resource[i];
> +
> +             if (resource_type(r) == IORESOURCE_MEM)

Make this:

        if (resource_type(r) != IORESOURCE_MEM)
                continue;

> +             {

And then you don't have to move all of this code to the right.

> +                     int j;
unsigned int
> +                     int nr = DIV_ROUND_UP(resource_size(r), PAGE_SIZE);

unsigned int
> +                     xen_pfn_t *gpfns = kmalloc(sizeof(xen_pfn_t) * nr,
> +                                                GFP_KERNEL);
> +                     xen_ulong_t *idxs = kmalloc(sizeof(xen_ulong_t) * nr,
> +                                                 GFP_KERNEL);
> +                     int *errs = kmalloc(sizeof(int) * nr, GFP_KERNEL);

You can use kzalloc.
> +                     struct xen_add_to_physmap_range xatp;

This declaration of variables and then setting does not look like that
pretty to my mind. (And it is a headache to debug if for example 'nr' ends up
being zero for example). Or worst -1U since you had it as 'int'.


> +
> +                     for (j = 0; j < nr; j++) {
> +                             gpfns[j] = (r->start >> PAGE_SHIFT) + j;
> +                             idxs[j] = (r->start >> PAGE_SHIFT) + j;
> +                             errs[j] = 0;

Then this can go away (because of kzalloc)
> +                     }
> +
> +                     xatp.domid = DOMID_SELF;
> +                     xatp.size = nr;
> +                     xatp.space = XENMAPSPACE_dev_mmio;
> +
> +                     set_xen_guest_handle(xatp.gpfns, gpfns);
> +                     set_xen_guest_handle(xatp.idxs, idxs);
> +                     set_xen_guest_handle(xatp.errs, errs);
> +
> +                     rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap_range,
> +                                               &xatp);
> +                     kfree(gpfns);
> +                     kfree(idxs);
> +                     kfree(errs);
> +                     if (rc != 0)
> +                             return rc;
> +             }
> +     }
> +
> +     return rc;
> +}
> +
> +static int xen_platform_notifier(struct notifier_block *nb,
> +                              unsigned long action, void *data)
> +{
> +     struct platform_device *pdev = to_platform_device(data);
> +     int r = 0;
> +
> +     if (!acpi_disabled && (action == BUS_NOTIFY_ADD_DEVICE))
> +             r = xen_map_platform_device_mmio(pdev);
> +
> +     if (r)
> +     {
> +             dev_err(&pdev->dev, "Failed to add_to_physmap device (%s) 
> mmio!\n",
> +                     pdev->name);
> +             return NOTIFY_OK;
> +     }
> +
> +     return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block platform_device_nb = {
> +     .notifier_call = xen_platform_notifier,
> +};
> +
> +static int __init register_xen_platform_notifier(void)
> +{
> +     if (!xen_initial_domain())
> +             return 0;
> +
> +     return bus_register_notifier(&platform_bus_type, &platform_device_nb);
> +}
> +
> +arch_initcall(register_xen_platform_notifier);
> -- 
> 2.1.0
> 
> 
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