Re: [PATCH v3 1/6] hv: Modify vmbus to search for all MMIO ranges available

[Vitaly Kuznetsov <vkuznets@redhat.com>]

jakeo@microsoft.com writes:

> From: Jake Oshins <jakeo@microsoft.com>
>
> Before this patch, hv_vmbus would search the ACPI namespace above its
> device looking for a _CRS (current resources) object, and hunt through
> the list of resources in there looking for one that described memory-
> mapped I/O space above the 4GB line.  It then exported the result for
> use in the hyperv_fb (frame buffer) driver.
>
> With this patch, hv_vmbus looks for all usable MMIO ranges above 1GB
> and makes a list of them, with the highest range first in the list,
> as drivers which can allocate from that range should allocate from it.
>
> Hyperv_fb is slightly modified to use this change.
>
> This change is necessary for supporting other Hyper-V related drivers,
> which might need MMIO space below 4GB.
>
> Signed-off-by: Jake Oshins <jakeo@microsoft.com>
> ---
>  drivers/hv/vmbus_drv.c          | 105 ++++++++++++++++++++++++++++++++++------
>  drivers/video/fbdev/hyperv_fb.c |   2 +-
>  include/linux/hyperv.h          |   2 +-
>  3 files changed, 92 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index c85235e..d0e8832 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -72,10 +72,7 @@ static struct notifier_block hyperv_panic_block = {
>  	.notifier_call = hyperv_panic_event,
>  };
>
> -struct resource hyperv_mmio = {
> -	.name  = "hyperv mmio",
> -	.flags = IORESOURCE_MEM,
> -};
> +struct resource *hyperv_mmio;
>  EXPORT_SYMBOL_GPL(hyperv_mmio);
>
>  static int vmbus_exists(void)
> @@ -982,30 +979,105 @@ void vmbus_device_unregister(struct hv_device *device_obj)
>
>  /*
> - * VMBUS is an acpi enumerated device. Get the the information we
> + * VMBUS is an acpi enumerated device. Get the information we
>   * need from DSDT.
>   */
> -
> +#define VTPM_BASE_ADDRESS 0xfed40000
>  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;
> +	struct resource **prev_res = NULL;
> +
>  	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.address.minimum;
> +		end = res->data.address32.address.maximum;
>  		break;
>
>  	case ACPI_RESOURCE_TYPE_ADDRESS64:
> -		hyperv_mmio.start = res->data.address64.address.minimum;
> -		hyperv_mmio.end = res->data.address64.address.maximum;
> +		start = res->data.address64.address.minimum;
> +		end = res->data.address64.address.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;
> +
> +	/* If this range overlaps the virtual TPM, truncate it. */
> +	if (end > VTPM_BASE_ADDRESS && start < VTPM_BASE_ADDRESS)
> +		end = VTPM_BASE_ADDRESS;
> +
> +	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)->end < new_res->start) {
> +			new_res->sibling = *old_res;
> +			if (prev_res)
> +				(*prev_res)->sibling = new_res;
> +			*old_res = new_res;
> +			break;
> +		}
> +
> +		prev_res = old_res;
> +		old_res = &(*old_res)->sibling;
> +
> +	} while (1);
>
>  	return AE_OK;
>  }
>
> +static int vmbus_acpi_remove(struct acpi_device *device)
> +{
> +	struct resource *cur_res;
> +	struct resource *next_res;
> +
> +	if (hyperv_mmio) {
> +		for (cur_res = hyperv_mmio; cur_res; cur_res = next_res) {
> +			next_res = cur_res->sibling;
> +			kfree(cur_res);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  static int vmbus_acpi_add(struct acpi_device *device)
>  {
>  	acpi_status result;
>  	int ret_val = -ENODEV;
> +	struct acpi_device *ancestor;
>
>  	hv_acpi_dev = device;
>
> @@ -1015,23 +1087,25 @@ 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)
> +			break;
>  	}
>  	ret_val = 0;
>
>  acpi_walk_err:
>  	complete(&probe_event);
> +	if (ret_val)
> +		vmbus_acpi_remove(device);
>  	return ret_val;
>  }
>
> @@ -1047,6 +1121,7 @@ static struct acpi_driver vmbus_acpi_driver = {
>  	.ids = vmbus_acpi_device_ids,
>  	.ops = {
>  		.add = vmbus_acpi_add,
> +		.remove = vmbus_acpi_remove,

This will probably need rebasing on top of current char-misc-next tree
as we already have commit e4ecb41c: "Drivers: hv: vmbus: introduce
vmbus_acpi_remove" there.

>  	},
>  };
>
> diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
> index 807ee22..b54ee1c 100644
> --- a/drivers/video/fbdev/hyperv_fb.c
> +++ b/drivers/video/fbdev/hyperv_fb.c
> @@ -688,7 +688,7 @@ 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 902c37a..21fa867 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -1245,7 +1245,7 @@ void hv_vss_deinit(void);
>  void hv_vss_onchannelcallback(void *);
>  void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid);
>
> -extern struct resource hyperv_mmio;
> +extern struct resource *hyperv_mmio;
>
>  /*
>   * Negotiated version with the Host.

-- 
  Vitaly