Re: + x86-fix-handling-of-the-reservetop-boot-option.patch added to -mm tree

[Jeremy Fitzhardinge <jeremy@goop.org>]

On 04/08/2010 01:58 AM, Liang Li wrote:
> On Wed, Apr 07, 2010 at 11:57:22PM -0700, Yinghai wrote:
>   
>> On 04/07/2010 09:59 PM, Liang Li wrote:
>>     
>>> On Wed, Apr 07, 2010 at 09:30:39PM -0700, Yinghai wrote:
>>>       
>>>> On 04/07/2010 06:53 PM, Liang Li wrote:
>>>>         
>>>>> Does this similar modification like this is more preferred?
>>>>>
>>>>> diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
>>>>> index a1dcfa3..30a3e97 100644
>>>>> --- a/arch/x86/include/asm/io.h
>>>>> +++ b/arch/x86/include/asm/io.h
>>>>> @@ -347,6 +347,7 @@ extern void __iomem *early_ioremap(resource_size_t phys_addr,
>>>>>  extern void __iomem *early_memremap(resource_size_t phys_addr,
>>>>>  				    unsigned long size);
>>>>>  extern void early_iounmap(void __iomem *addr, unsigned long size);
>>>>> +extern void fixup_early_ioremap(void);
>>>>>  
>>>>>  #define IO_SPACE_LIMIT 0xffff
>>>>>  
>>>>> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
>>>>> index ea82ef0..fe06296 100644
>>>>> --- a/arch/x86/mm/ioremap.c
>>>>> +++ b/arch/x86/mm/ioremap.c
>>>>> @@ -448,6 +448,23 @@ static inline void __init early_clear_fixmap(enum fixed_addresses idx)
>>>>>  static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata;
>>>>>  static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata;
>>>>>  
>>>>> +void __init fixup_early_ioremap(void)
>>>>> +{
>>>>> +	int i;
>>>>> +	for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
>>>>> +		if (prev_map[i])
>>>>> +			break;
>>>>> +	}
>>>>> +
>>>>> +	if (i == FIX_BTMAPS_SLOTS)
>>>>>           
>>>> <
>>>>         
>>>>> +		WARN_ON(1);
>>>>>           
>>>> BUG_ON()
>>>>         
>>>>> +
>>>>> +	for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
>>>>> +		slot_virt[i] = __fix_to_virt(FIX_BTMAP_BEGIN - NR_FIX_BTMAPS * i);
>>>>> +
>>>>>           
>>>> need to clear the old PMD, and set new PMD.
>>>>
>>>> so you can clear old PMD and call early_ioremap_init() in fixup_early_ioremap()
>>>>         
>>> Call early_ioremap_init will do the update PMD work. So the preferred
>>> patch would be:
>>> ---------------
>>> From 61fe7a116cbbf6eef98a49b88ed5861ed9ebd32d Mon Sep 17 00:00:00 2001
>>> From: Liang Li <liang.li@windriver.com>
>>> Date: Mon, 22 Mar 2010 18:38:14 +0800
>>> Subject: [PATCH] x86: let 'reservetop' functioning right
>>>
>>> When specify 'reservetop=0xbadc0de' kernel parameter, the kernel will
>>> stop booting due to a early_ioremap bug that relate to commit 8827247ff.
>>>
>>> The root cause of boot failure problem is the value of 'slot_virt[i]'
>>> was initialized in setup_arch->early_ioremap_init. But later in
>>> setup_arch, the function 'parse_early_param' will modify 'FIXADDR_TOP'
>>> when 'reservetop=0xbadc0de' being specified.
>>>
>>> When reservetop being handled then FIXADDR_TOP get adjusted, Hence check
>>> prev_map then re-initialize slot_virt and PMD based on new FIXADDR_TOP.
>>>
>>> Signed-off-by: Liang Li <liang.li@windriver.com>
>>> Cc: Wang Chen <wangchen@cn.fujitsu.com>
>>> Cc: Ingo Molnar <mingo@elte.hu>
>>> Cc: Thomas Gleixner <tglx@linutronix.de>
>>> Cc: "H. Peter Anvin" <hpa@zytor.com>
>>> Cc: Yinghai Lu <yinghai@kernel.org>
>>> Cc: Andrew Morton <akpm@linux-foundation.org>
>>> ---
>>>  arch/x86/include/asm/io.h |    1 +
>>>  arch/x86/mm/ioremap.c     |   15 +++++++++++++++
>>>  arch/x86/mm/pgtable.c     |    2 ++
>>>  3 files changed, 18 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
>>> index a1dcfa3..30a3e97 100644
>>> --- a/arch/x86/include/asm/io.h
>>> +++ b/arch/x86/include/asm/io.h
>>> @@ -347,6 +347,7 @@ extern void __iomem *early_ioremap(resource_size_t phys_addr,
>>>  extern void __iomem *early_memremap(resource_size_t phys_addr,
>>>  				    unsigned long size);
>>>  extern void early_iounmap(void __iomem *addr, unsigned long size);
>>> +extern void fixup_early_ioremap(void);
>>>  
>>>  #define IO_SPACE_LIMIT 0xffff
>>>  
>>> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
>>> index 5eb1ba7..e4ab706 100644
>>> --- a/arch/x86/mm/ioremap.c
>>> +++ b/arch/x86/mm/ioremap.c
>>> @@ -448,6 +448,21 @@ static inline void __init early_clear_fixmap(enum fixed_addresses idx)
>>>  static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata;
>>>  static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata;
>>>  
>>> +void __init fixup_early_ioremap(void)
>>> +{
>>> +	int i;
>>> +	for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
>>> +		if (prev_map[i])
>>> +			break;
>>> +	}
>>> +
>>> +	if (i < FIX_BTMAPS_SLOTS)
>>> +		BUG_ON(1);
>>> +
>>> +	early_ioremap_init();
>>> +	return;
>>> +}
>>> +
>>>  static int __init check_early_ioremap_leak(void)
>>>  {
>>>  	int count = 0;
>>> diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
>>> index 5c4ee42..ea4d54c 100644
>>> --- a/arch/x86/mm/pgtable.c
>>> +++ b/arch/x86/mm/pgtable.c
>>> @@ -4,6 +4,7 @@
>>>  #include <asm/pgtable.h>
>>>  #include <asm/tlb.h>
>>>  #include <asm/fixmap.h>
>>> +#include <asm/io.h>
>>>  
>>>  #define PGALLOC_GFP GFP_KERNEL | __GFP_NOTRACK | __GFP_REPEAT | __GFP_ZERO
>>>  
>>> @@ -351,6 +352,7 @@ void __init reserve_top_address(unsigned long reserve)
>>>  	printk(KERN_INFO "Reserving virtual address space above 0x%08x\n",
>>>  	       (int)-reserve);
>>>  	__FIXADDR_TOP = -reserve - PAGE_SIZE;
>>> +	fixup_early_ioremap();
>>>  #endif
>>>  }
>>>  
>>> -----------
>>> Acceptable?
>>>
>>>       
>> good to me.
>>
>> may need to ask xen/lguest/vmi related to check that too.
>>
>> arch/x86/kernel/vmi_32.c:       reserve_top_address(-vmi_rom->virtual_top);
>> arch/x86/lguest/boot.c: reserve_top_address(lguest_data.reserve_mem);
>> arch/x86/mm/pgtable_32.c:       reserve_top_address(address);
>> arch/x86/xen/mmu.c:     reserve_top_address(-top);
>>     
> When linux as vmi/xen/lguest guest OS, kernel call reserve_top_address
> before start_kernel. It is far before the start_kernel hence far before
> setup_arch->early_ioremap_init. So it is unsafe to place
> fixup_early_ioremap inside reserve_top_address. So I think the patch
> should be:
>   

Yes indeed.  That looks better.

Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Thanks,
    J

> From 7cefa9a80c4434f2941a7072d39b1f1ffc08a40f Mon Sep 17 00:00:00 2001
> From: Liang Li <liang.li@windriver.com>
> Date: Mon, 22 Mar 2010 18:38:14 +0800
> Subject: [PATCH] x86: let 'reservetop' functioning right
>
> When specify 'reservetop=0xbadc0de' kernel parameter, the kernel will
> stop booting due to a early_ioremap bug that relate to commit 8827247ff.
>
> The root cause of boot failure problem is the value of 'slot_virt[i]'
> was initialized in setup_arch->early_ioremap_init. But later in
> setup_arch, the function 'parse_early_param' will modify 'FIXADDR_TOP'
> when 'reservetop=0xbadc0de' being specified.
>
> When reservetop being handled then FIXADDR_TOP get adjusted, Hence check
> prev_map then re-initialize slot_virt and PMD based on new FIXADDR_TOP.
>
> Signed-off-by: Liang Li <liang.li@windriver.com>
> Cc: Wang Chen <wangchen@cn.fujitsu.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Yinghai Lu <yinghai@kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
>  arch/x86/include/asm/io.h |    1 +
>  arch/x86/mm/ioremap.c     |   15 +++++++++++++++
>  arch/x86/mm/pgtable_32.c  |    1 +
>  3 files changed, 17 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
> index a1dcfa3..30a3e97 100644
> --- a/arch/x86/include/asm/io.h
> +++ b/arch/x86/include/asm/io.h
> @@ -347,6 +347,7 @@ extern void __iomem *early_ioremap(resource_size_t phys_addr,
>  extern void __iomem *early_memremap(resource_size_t phys_addr,
>  				    unsigned long size);
>  extern void early_iounmap(void __iomem *addr, unsigned long size);
> +extern void fixup_early_ioremap(void);
>  
>  #define IO_SPACE_LIMIT 0xffff
>  
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index 5eb1ba7..e4ab706 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -448,6 +448,21 @@ static inline void __init early_clear_fixmap(enum fixed_addresses idx)
>  static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata;
>  static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata;
>  
> +void __init fixup_early_ioremap(void)
> +{
> +	int i;
> +	for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
> +		if (prev_map[i])
> +			break;
> +	}
> +
> +	if (i < FIX_BTMAPS_SLOTS)
> +		BUG_ON(1);
> +
> +	early_ioremap_init();
> +	return;
> +}
> +
>  static int __init check_early_ioremap_leak(void)
>  {
>  	int count = 0;
> diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c
> index 1a8faf0..26eadaa 100644
> --- a/arch/x86/mm/pgtable_32.c
> +++ b/arch/x86/mm/pgtable_32.c
> @@ -128,6 +128,7 @@ static int __init parse_reservetop(char *arg)
>  
>  	address = memparse(arg, &arg);
>  	reserve_top_address(address);
> +	fixup_early_ioremap();
>  	return 0;
>  }
>  early_param("reservetop", parse_reservetop);
>