Date:	Fri, 23 Jan 2015 10:59:25 +0100
From:	Vitaly Kuznetsov <vkuznets@...hat.com>
To:	Jake Oshins <jakeo@...rosoft.com>
Cc:	gregkh@...uxfoundation.org, kys@...rosoft.com,
	linux-kernel@...r.kernel.org, devel@...uxdriverproject.org,
	olaf@...fle.de, apw@...onical.com
Subject: Re: [PATCH 1/1] drivers:hv:vmbus Allow for more than one MMIO range for children.

Jake Oshins <jakeo@...rosoft.com> writes:

> Signed-off-by: Jake Oshins <jakeo@...rosoft.com>
> ---
>  drivers/hv/vmbus_drv.c          | 85 +++++++++++++++++++++++++++++++++--------
>  drivers/video/fbdev/hyperv_fb.c |  2 +-
>  include/linux/hyperv.h          |  2 +-
>  3 files changed, 72 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 4d6b269..ba5b7a1 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -43,10 +43,7 @@ static struct tasklet_struct msg_dpc;
>  static struct completion probe_event;
>  static int irq;
>
> -struct resource hyperv_mmio = {
> -	.name  = "hyperv mmio",
> -	.flags = IORESOURCE_MEM,
> -};
> +struct resource *hyperv_mmio;
>  EXPORT_SYMBOL_GPL(hyperv_mmio);
>
>  static int vmbus_exists(void)
> @@ -849,23 +846,74 @@ void vmbus_device_unregister(struct hv_device *device_obj)
>
>  /*
> - * VMBUS is an acpi enumerated device. Get the the information we
> - * need from DSDT.
> + * VMBUS is an acpi enumerated device. Get the
> + * information we need from DSDT.
>   */
>
>  static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx)
>  {
> +	resource_size_t start = 0;
> +	resource_size_t end = 0;
> +	struct resource *new_res;
> +	struct resource **old_res = &hyperv_mmio;
> +
>  	switch (res->type) {
>  	case ACPI_RESOURCE_TYPE_IRQ:
>  		irq = res->data.irq.interrupts[0];
> +		return AE_OK;
> +
> +	/*
> +	 * "Address" descriptors are for bus windows. Ignore
> +	 * "memory" descriptors, which are for registers on
> +	 * devices.
> +	 */
> +	case ACPI_RESOURCE_TYPE_ADDRESS32:
> +		start = res->data.address32.minimum;
> +		end = res->data.address32.maximum;
>  		break;
>
>  	case ACPI_RESOURCE_TYPE_ADDRESS64:
> -		hyperv_mmio.start = res->data.address64.minimum;
> -		hyperv_mmio.end = res->data.address64.maximum;
> +		start = res->data.address64.minimum;
> +		end = res->data.address64.maximum;
>  		break;
> +
> +	default:
> +		/* Unused resource type */
> +		return AE_OK;
>  	}
>
> +	/*
> +	 * Ignore ranges that are below 1MB, as they're not
> +	 * necessary or useful here.
> +	 */
> +	if (end < 0x100000)
> +		return AE_OK;
> +
> +	new_res = kzalloc(sizeof(*new_res), GFP_ATOMIC);
> +	if (!new_res)
> +		return AE_NO_MEMORY;
> +
> +	new_res->name = "hyperv mmio";
> +	new_res->flags = IORESOURCE_MEM;
> +	new_res->start = start;
> +	new_res->end = end;
> +
> +	do {
> +		if (!*old_res) {
> +			*old_res = new_res;
> +			break;
> +		}
> +
> +		if ((*old_res)->start > new_res->end) {
> +			new_res->sibling = *old_res;
> +			*old_res = new_res;
> +			break;
> +		}
> +
> +		old_res = &(*old_res)->sibling;
> +
> +	} while (1);
> +
>  	return AE_OK;
>  }
>
> @@ -873,6 +921,7 @@ static int vmbus_acpi_add(struct acpi_device *device)
>  {
>  	acpi_status result;
>  	int ret_val = -ENODEV;
> +	struct acpi_device *ancestor;
>
>  	hv_acpi_dev = device;
>
> @@ -882,18 +931,22 @@ static int vmbus_acpi_add(struct acpi_device *device)
>  	if (ACPI_FAILURE(result))
>  		goto acpi_walk_err;
>  	/*
> -	 * The parent of the vmbus acpi device (Gen2 firmware) is the VMOD that
> -	 * has the mmio ranges. Get that.
> +	 * Some ancestor of the vmbus acpi device (Gen1 or Gen2
> +	 * firmware) is the VMOD that has the mmio ranges. Get that.
>  	 */
> -	if (device->parent) {
> -		result = acpi_walk_resources(device->parent->handle,
> +	for (ancestor = device->parent;
> +		ancestor;
> +		ancestor = ancestor->parent) {
> +		result = acpi_walk_resources(ancestor->handle,
>  					METHOD_NAME__CRS,
>  					vmbus_walk_resources, NULL);
>
>  		if (ACPI_FAILURE(result))
> -			goto acpi_walk_err;
> -		if (hyperv_mmio.start && hyperv_mmio.end)
> -			request_resource(&iomem_resource, &hyperv_mmio);
> +			continue;
> +		if (hyperv_mmio) {
> +			request_resource(&iomem_resource, hyperv_mmio);
> +			break;
> +		}
>  	}
>  	ret_val = 0;
>
> @@ -962,6 +1015,8 @@ static void __exit vmbus_exit(void)
>  	hv_remove_vmbus_irq();
>  	vmbus_free_channels();
>  	bus_unregister(&hv_bus);
> +	if (hyperv_mmio)
> +		release_resource(hyperv_mmio);

I suggese we create a special release handler and register it within
acpi_driver.ops (the way I did it in https://lkml.org/lkml/2015/1/21/669
but now I'm going to drop it from my series as your patch is supposed to
solve the issue) instead as it naturally belongs there.

>  	hv_cleanup();
>  	acpi_bus_unregister_driver(&vmbus_acpi_driver);
>  }
> diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
> index 4254336..003c8f0 100644
> --- a/drivers/video/fbdev/hyperv_fb.c
> +++ b/drivers/video/fbdev/hyperv_fb.c
> @@ -686,7 +686,7 @@ static int hvfb_getmem(struct fb_info *info)
>  	par->mem.name = KBUILD_MODNAME;
>  	par->mem.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
>  	if (gen2vm) {
> -		ret = allocate_resource(&hyperv_mmio, &par->mem,
> +		ret = allocate_resource(hyperv_mmio, &par->mem,
>  					screen_fb_size,
>  					0, -1,
>  					screen_fb_size,
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index 476c685..8903689 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -1178,7 +1178,7 @@ int hv_vss_init(struct hv_util_service *);
>  void hv_vss_deinit(void);
>  void hv_vss_onchannelcallback(void *);
>
> -extern struct resource hyperv_mmio;
> +extern struct resource *hyperv_mmio;
>
>  /*
>   * Negotiated version with the Host.

-- 
  Vitaly
--
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