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From:   "Rafael J. Wysocki" <rjw@rjwysocki.net>
To:     Yisheng Xie <xieyisheng1@huawei.com>
Cc:     bhelgaas@google.com, lenb@kernel.org, linux-pci@vger.kernel.org,
        linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
        guohanjun@huawei.com, jcm@redhat.com, toshi.kani@hpe.com,
        tanxiaojun@huawei.com, wangzhou1@hisilicon.com,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Hanjun Guo <hanjun.guo@linaro.org>
Subject: Re: [PATCH v2 1/2] PCI ACPI: Avoid panic when PCI IO resource's size is not page aligned
Date:   Tue, 01 May 2018 11:28:31 +0200
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On Saturday, March 31, 2018 9:12:22 AM CEST Yisheng Xie wrote:
> Zhou reported a bug on Hisilicon arm64 D06 platform with 64KB page size:
> 
>  [    2.470908] kernel BUG at lib/ioremap.c:72!
>  [    2.475079] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
>  [    2.480551] Modules linked in:
>  [    2.483594] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.16.0-rc7-00062-g0b41260-dirty #23
>  [    2.491756] Hardware name: Huawei D06/D06, BIOS Hisilicon D06 UEFI Nemo 2.0 RC0 - B120 03/23/2018
>  [    2.500614] pstate: 80c00009 (Nzcv daif +PAN +UAO)
>  [    2.505395] pc : ioremap_page_range+0x268/0x36c
>  [    2.509912] lr : pci_remap_iospace+0xe4/0x100
>  [...]
>  [    2.603733] Call trace:
>  [    2.606168]  ioremap_page_range+0x268/0x36c
>  [    2.610337]  pci_remap_iospace+0xe4/0x100
>  [    2.614334]  acpi_pci_probe_root_resources+0x1d4/0x214
>  [    2.619460]  pci_acpi_root_prepare_resources+0x18/0xa8
>  [    2.624585]  acpi_pci_root_create+0x98/0x214
>  [    2.628843]  pci_acpi_scan_root+0x124/0x20c
>  [    2.633013]  acpi_pci_root_add+0x224/0x494
>  [    2.637096]  acpi_bus_attach+0xf8/0x200
>  [    2.640918]  acpi_bus_attach+0x98/0x200
>  [    2.644740]  acpi_bus_attach+0x98/0x200
>  [    2.648562]  acpi_bus_scan+0x48/0x9c
>  [    2.652125]  acpi_scan_init+0x104/0x268
>  [    2.655948]  acpi_init+0x308/0x374
>  [    2.659337]  do_one_initcall+0x48/0x14c
>  [    2.663160]  kernel_init_freeable+0x19c/0x250
>  [    2.667504]  kernel_init+0x10/0x100
>  [    2.670979]  ret_from_fork+0x10/0x18
> 
> The cause is the size of PCI IO resource is 32KB, which is 4K aligned but
> not 64KB aligned, however, ioremap_page_range() request the range as page
> aligned or it will trigger a BUG_ON() on ioremap_pte_range() it calls, as
> ioremap_pte_range increase the addr by PAGE_SIZE, which makes addr != end
> until trigger BUG_ON, if its incoming end is not page aligned. More detail
> trace is as following:
> 
>  ioremap_page_range
>  -> ioremap_p4d_range
>     -> ioremap_p4d_range
>        -> ioremap_pud_range
>           -> ioremap_pmd_range
>              -> ioremap_pte_range
> 
> This patch fix the bug by align the size of PCI IO resource to PAGE_SIZE.
> 
> Reported-by: Zhou Wang <wangzhou1@hisilicon.com>
> Tested-by: Xiaojun Tan <tanxiaojun@huawei.com>
> Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
> ---
> I mark this as v2 for I have post a RFC version:
> 
>  https://lkml.org/lkml/2018/3/30/8
>  
> v2:
>  * Let the caller of ioremap_page_range() align the request by PAGE_SIZE - per Toshi
> 
> Thanks
> Yisheng
> 
>  drivers/acpi/pci_root.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 6fc204a..b758ca3 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -746,7 +746,7 @@ static void acpi_pci_root_remap_iospace(struct resource_entry *entry)
>  		goto err;
>  
>  	res->start = port;
> -	res->end = port + length - 1;
> +	res->end = PAGE_ALIGN(port + length) - 1;

Shouldn't pci_remap_iospace() sanitize its arguments instead?

>  	entry->offset = port - pci_addr;
>  
>  	if (pci_remap_iospace(res, cpu_addr) < 0)
>