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Message-ID: <87y4obaxp8.fsf@vitty.brq.redhat.com>
Date: Fri, 06 Feb 2015 16:04:03 +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 v2 1/1] drivers:hv:vmbus drivers:hv:vmbus Allow for more than one MMIO range for children
Jake Oshins <jakeo@...rosoft.com> writes:
> This set of changes finds the _CRS object in the ACPI namespace
> that contains memory address space descriptors, intended to convey
> to VMBus which ranges of memory-mapped I/O space are available for
> child devices, and then builds a resource list that contains all
> those ranges. Without this change, only some of the memory-mapped
> I/O space will be available for child devices, and only in some
> virtual BIOS configurations (Generation 2 VMs).
>
> This patch has been updated with feedback from Vitaly Kuznetsov.
> Cleanup is now driven by the acpi remove callback function.
Sorry for beeing late with this message but I'm seeing issues with this
commit. I added some debug to figure out what's going on and here is
what I see:
With Gen1 VM we end up doing request_resource for two ranges:
f8000000 - fffbffff
fe0000000 - fffefffff
request_resource() fails (as we already have PCI device at f8000000 I
suppose?) but we don't check the return value. release_resource on
module unload crashes the kernel:
[ 78.314344] BUG: unable to handle kernel NULL pointer dereference at
0000000000000030
[ 78.315021] IP: [<ffffffff8107fac5>] release_resource+0x25/0x90
[ 78.315021] PGD 78c67067 PUD 78c5a067 PMD 0
[ 78.315021] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
[ 78.315021] Modules linked in: hv_vmbus(-)
...
If I'm not mistaken, before the change we didn't do any
request_resource() for Gen1 VMs at all.
With Gen2 VM we do request_resource for fe0000000 - fffffffff range
only, that means this commit doesn't change anything.
Can you please take a look? I'd like to help but I don't completely
understand the essense of the change wrt Gen1 VMs with PCI devices.
Thanks,
>
> Signed-off-by: Jake Oshins <jakeo@...rosoft.com>
> ---
> drivers/hv/vmbus_drv.c | 99 +++++++++++++++++++++++++++++++++------
> drivers/video/fbdev/hyperv_fb.c | 2 +-
> include/linux/hyperv.h | 2 +-
> 3 files changed, 86 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 4d6b269..ed618ac 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)
> @@ -849,30 +846,98 @@ 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;
> }
>
> +static int vmbus_acpi_remove(struct acpi_device *device)
> +{
> + struct resource *cur_res;
> + struct resource *next_res;
> +
> + if (hyperv_mmio) {
> + release_resource(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;
>
> @@ -882,23 +947,26 @@ 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;
>
> acpi_walk_err:
> complete(&probe_event);
> + vmbus_acpi_remove(device);
> return ret_val;
> }
>
> @@ -914,6 +982,7 @@ static struct acpi_driver vmbus_acpi_driver = {
> .ids = vmbus_acpi_device_ids,
> .ops = {
> .add = vmbus_acpi_add,
> + .remove = vmbus_acpi_remove,
> },
> };
>
> 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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