Re: [GIT PULL] x86/mm changes for v3.2

["hpanvin@gmail.com" <hpa@zytor.com>]

Yes... I thought we had agreed that as ugly as the hook it is better than the fragility of second-guessing other code.  I would like to see something automatically correct by construction, but that seems to be really difficult for reasons I don't remember, possibly having to do with bad Xen setup APIs.

Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote:

>On Wed, Oct 26, 2011 at 05:36:00PM +0200, Ingo Molnar wrote:
>> Linus,
>> 
>> Please pull the latest x86-mm-for-linus git tree from:
>> 
>>    git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
>x86-mm-for-linus
>> 
>Hey Ingo,
>
>When I spoke to hpa (LinuxCon in Canada) he mentioned that you guys
>decided
>against this patchset and just stick with the
>
>"x86,xen: introduce x86_init.mapping.pagetable_reserve"?
>
>Maybe I am misremembering the conversation - there was a fair amount of
>beer
>involved.
>
>>  Thanks,
>> 
>> 	Ingo
>> 
>> ------------------>
>> Stefano Stabellini (5):
>>       x86, mm: Calculate precisely the memory needed by
>init_memory_mapping
>>       Revert "x86,xen: introduce x86_init.mapping.pagetable_reserve"
>>       x86, init : Move memblock_x86_reserve_range PGTABLE to
>find_early_table_space
>>       x86-64, mm: Do not assume head_64.S used 4KB pages when
>!use_pse
>>       x86_32: Calculate additional memory needed by the fixmap
>> 
>> 
>>  arch/x86/include/asm/pgtable_types.h |    1 -
>>  arch/x86/include/asm/x86_init.h      |   12 ---
>>  arch/x86/kernel/x86_init.c           |    4 -
>>  arch/x86/mm/init.c                   |  147
>+++++++++++++++++++++++++---------
>>  arch/x86/xen/mmu.c                   |   15 ----
>>  5 files changed, 109 insertions(+), 70 deletions(-)
>> 
>> diff --git a/arch/x86/include/asm/pgtable_types.h
>b/arch/x86/include/asm/pgtable_types.h
>> index d56187c..7db7723 100644
>> --- a/arch/x86/include/asm/pgtable_types.h
>> +++ b/arch/x86/include/asm/pgtable_types.h
>> @@ -299,7 +299,6 @@ int phys_mem_access_prot_allowed(struct file
>*file, unsigned long pfn,
>>  /* Install a pte for a particular vaddr in kernel space. */
>>  void set_pte_vaddr(unsigned long vaddr, pte_t pte);
>>  
>> -extern void native_pagetable_reserve(u64 start, u64 end);
>>  #ifdef CONFIG_X86_32
>>  extern void native_pagetable_setup_start(pgd_t *base);
>>  extern void native_pagetable_setup_done(pgd_t *base);
>> diff --git a/arch/x86/include/asm/x86_init.h
>b/arch/x86/include/asm/x86_init.h
>> index d3d8590..643ebf2 100644
>> --- a/arch/x86/include/asm/x86_init.h
>> +++ b/arch/x86/include/asm/x86_init.h
>> @@ -68,17 +68,6 @@ struct x86_init_oem {
>>  };
>>  
>>  /**
>> - * struct x86_init_mapping - platform specific initial kernel
>pagetable setup
>> - * @pagetable_reserve:	reserve a range of addresses for kernel
>pagetable usage
>> - *
>> - * For more details on the purpose of this hook, look in
>> - * init_memory_mapping and the commit that added it.
>> - */
>> -struct x86_init_mapping {
>> -	void (*pagetable_reserve)(u64 start, u64 end);
>> -};
>> -
>> -/**
>>   * struct x86_init_paging - platform specific paging functions
>>   * @pagetable_setup_start:	platform specific pre paging_init() call
>>   * @pagetable_setup_done:	platform specific post paging_init() call
>> @@ -134,7 +123,6 @@ struct x86_init_ops {
>>  	struct x86_init_mpparse		mpparse;
>>  	struct x86_init_irqs		irqs;
>>  	struct x86_init_oem		oem;
>> -	struct x86_init_mapping		mapping;
>>  	struct x86_init_paging		paging;
>>  	struct x86_init_timers		timers;
>>  	struct x86_init_iommu		iommu;
>> diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
>> index 6f164bd..6eee082 100644
>> --- a/arch/x86/kernel/x86_init.c
>> +++ b/arch/x86/kernel/x86_init.c
>> @@ -61,10 +61,6 @@ struct x86_init_ops x86_init __initdata = {
>>  		.banner			= default_banner,
>>  	},
>>  
>> -	.mapping = {
>> -		.pagetable_reserve		= native_pagetable_reserve,
>> -	},
>> -
>>  	.paging = {
>>  		.pagetable_setup_start	= native_pagetable_setup_start,
>>  		.pagetable_setup_done	= native_pagetable_setup_done,
>> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
>> index 3032644..a90ccc4 100644
>> --- a/arch/x86/mm/init.c
>> +++ b/arch/x86/mm/init.c
>> @@ -28,22 +28,110 @@ int direct_gbpages
>>  #endif
>>  ;
>>  
>> -static void __init find_early_table_space(unsigned long end, int
>use_pse,
>> -					  int use_gbpages)
>> +static unsigned long __init find_early_fixmap_space(void)
>>  {
>> -	unsigned long puds, pmds, ptes, tables, start = 0, good_end = end;
>> +	unsigned long size = 0;
>> +#ifdef CONFIG_X86_32
>> +	int kmap_begin_pmd_idx, kmap_end_pmd_idx;
>> +	int fixmap_begin_pmd_idx, fixmap_end_pmd_idx;
>> +	int btmap_begin_pmd_idx;
>> +
>> +	fixmap_begin_pmd_idx =
>> +		__fix_to_virt(__end_of_fixed_addresses - 1) >> PMD_SHIFT;
>> +	/*
>> +	 * fixmap_end_pmd_idx is the end of the fixmap minus the PMD that
>> +	 * has been defined in the data section by head_32.S (see
>> +	 * initial_pg_fixmap).
>> +	 * Note: This is similar to what
>early_ioremap_page_table_range_init
>> +	 * does except that the "end" has PMD_SIZE expunged as per previous
>> +	 * comment.
>> +	 */
>> +	fixmap_end_pmd_idx = (FIXADDR_TOP - 1) >> PMD_SHIFT;
>> +	btmap_begin_pmd_idx = __fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT;
>> +	kmap_begin_pmd_idx = __fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
>> +	kmap_end_pmd_idx = __fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
>> +
>> +	size = fixmap_end_pmd_idx - fixmap_begin_pmd_idx;
>> +	/*
>> +	 * early_ioremap_init has already allocated a PMD at
>> +	 * btmap_begin_pmd_idx
>> +	 */
>> +	if (btmap_begin_pmd_idx < fixmap_end_pmd_idx)
>> +		size--;
>> +
>> +#ifdef CONFIG_HIGHMEM
>> +	/*
>> +	 * see page_table_kmap_check: if the kmap spans multiple PMDs, make
>> +	 * sure the pte pages are allocated contiguously. It might need up
>> +	 * to two additional pte pages to replace the page declared by
>> +	 * head_32.S and the one allocated by early_ioremap_init, if they
>> +	 * are even partially used for the kmap.
>> +	 */
>> +	if (kmap_begin_pmd_idx != kmap_end_pmd_idx) {
>> +		if (kmap_end_pmd_idx == fixmap_end_pmd_idx)
>> +			size++;
>> +		if (btmap_begin_pmd_idx >= kmap_begin_pmd_idx &&
>> +				btmap_begin_pmd_idx <= kmap_end_pmd_idx)
>> +			size++;
>> +	}
>> +#endif
>> +#endif
>> +	return (size * PMD_SIZE + PAGE_SIZE - 1) >> PAGE_SHIFT;
>> +}
>> +
>> +static void __init find_early_table_space(unsigned long start,
>> +		unsigned long end, int use_pse, int use_gbpages)
>> +{
>> +	unsigned long pmds = 0, ptes = 0, tables = 0, good_end = end,
>> +				  pud_mapped = 0, pmd_mapped = 0, size = end - start;
>>  	phys_addr_t base;
>>  
>> -	puds = (end + PUD_SIZE - 1) >> PUD_SHIFT;
>> -	tables = roundup(puds * sizeof(pud_t), PAGE_SIZE);
>> +	pud_mapped = DIV_ROUND_UP(PFN_PHYS(max_pfn_mapped),
>> +			(PUD_SIZE * PTRS_PER_PUD));
>> +	pud_mapped *= (PUD_SIZE * PTRS_PER_PUD);
>> +	pmd_mapped = DIV_ROUND_UP(PFN_PHYS(max_pfn_mapped),
>> +			(PMD_SIZE * PTRS_PER_PMD));
>> +	pmd_mapped *= (PMD_SIZE * PTRS_PER_PMD);
>> +
>> +	/*
>> +	 * On x86_64 do not limit the size we need to cover with 4KB pages
>> +	 * depending on the initial allocation because head_64.S always
>uses
>> +	 * 2MB pages.
>> +	 */
>> +#ifdef CONFIG_X86_32
>> +	if (start < PFN_PHYS(max_pfn_mapped)) {
>> +		if (PFN_PHYS(max_pfn_mapped) < end)
>> +			size -= PFN_PHYS(max_pfn_mapped) - start;
>> +		else
>> +			size = 0;
>> +	}
>> +#endif
>> +
>> +#ifndef __PAGETABLE_PUD_FOLDED
>> +	if (end > pud_mapped) {
>> +		unsigned long puds;
>> +		if (start < pud_mapped)
>> +			puds = (end - pud_mapped + PUD_SIZE - 1) >> PUD_SHIFT;
>> +		else
>> +			puds = (end - start + PUD_SIZE - 1) >> PUD_SHIFT;
>> +		tables += roundup(puds * sizeof(pud_t), PAGE_SIZE);
>> +	}
>> +#endif
>>  
>>  	if (use_gbpages) {
>>  		unsigned long extra;
>>  
>>  		extra = end - ((end>>PUD_SHIFT) << PUD_SHIFT);
>>  		pmds = (extra + PMD_SIZE - 1) >> PMD_SHIFT;
>> -	} else
>> -		pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT;
>> +	}
>> +#ifndef __PAGETABLE_PMD_FOLDED
>> +	else if (end > pmd_mapped) {
>> +		if (start < pmd_mapped)
>> +			pmds = (end - pmd_mapped + PMD_SIZE - 1) >> PMD_SHIFT;
>> +		else
>> +			pmds = (end - start + PMD_SIZE - 1) >> PMD_SHIFT;
>> +	}
>> +#endif
>>  
>>  	tables += roundup(pmds * sizeof(pmd_t), PAGE_SIZE);
>>  
>> @@ -51,23 +139,22 @@ static void __init
>find_early_table_space(unsigned long end, int use_pse,
>>  		unsigned long extra;
>>  
>>  		extra = end - ((end>>PMD_SHIFT) << PMD_SHIFT);
>> -#ifdef CONFIG_X86_32
>> -		extra += PMD_SIZE;
>> -#endif
>>  		ptes = (extra + PAGE_SIZE - 1) >> PAGE_SHIFT;
>>  	} else
>> -		ptes = (end + PAGE_SIZE - 1) >> PAGE_SHIFT;
>> +		ptes = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
>> +
>> +	ptes += find_early_fixmap_space();
>>  
>>  	tables += roundup(ptes * sizeof(pte_t), PAGE_SIZE);
>>  
>> -#ifdef CONFIG_X86_32
>> -	/* for fixmap */
>> -	tables += roundup(__end_of_fixed_addresses * sizeof(pte_t),
>PAGE_SIZE);
>> +	if (!tables)
>> +		return;
>>  
>> +#ifdef CONFIG_X86_32
>>  	good_end = max_pfn_mapped << PAGE_SHIFT;
>>  #endif
>>  
>> -	base = memblock_find_in_range(start, good_end, tables, PAGE_SIZE);
>> +	base = memblock_find_in_range(0x00, good_end, tables, PAGE_SIZE);
>>  	if (base == MEMBLOCK_ERROR)
>>  		panic("Cannot find space for the kernel page tables");
>>  
>> @@ -77,11 +164,10 @@ static void __init
>find_early_table_space(unsigned long end, int use_pse,
>>  
>>  	printk(KERN_DEBUG "kernel direct mapping tables up to %lx @
>%lx-%lx\n",
>>  		end, pgt_buf_start << PAGE_SHIFT, pgt_buf_top << PAGE_SHIFT);
>> -}
>>  
>> -void __init native_pagetable_reserve(u64 start, u64 end)
>> -{
>> -	memblock_x86_reserve_range(start, end, "PGTABLE");
>> +	if (pgt_buf_top > pgt_buf_start)
>> +		memblock_x86_reserve_range(pgt_buf_start << PAGE_SHIFT,
>> +				 pgt_buf_top << PAGE_SHIFT, "PGTABLE");
>>  }
>>  
>>  struct map_range {
>> @@ -261,7 +347,7 @@ unsigned long __init_refok
>init_memory_mapping(unsigned long start,
>>  	 * nodes are discovered.
>>  	 */
>>  	if (!after_bootmem)
>> -		find_early_table_space(end, use_pse, use_gbpages);
>> +		find_early_table_space(start, end, use_pse, use_gbpages);
>>  
>>  	for (i = 0; i < nr_range; i++)
>>  		ret = kernel_physical_mapping_init(mr[i].start, mr[i].end,
>> @@ -275,24 +361,9 @@ unsigned long __init_refok
>init_memory_mapping(unsigned long start,
>>  
>>  	__flush_tlb_all();
>>  
>> -	/*
>> -	 * Reserve the kernel pagetable pages we used (pgt_buf_start -
>> -	 * pgt_buf_end) and free the other ones (pgt_buf_end - pgt_buf_top)
>> -	 * so that they can be reused for other purposes.
>> -	 *
>> -	 * On native it just means calling memblock_x86_reserve_range, on
>Xen it
>> -	 * also means marking RW the pagetable pages that we allocated
>before
>> -	 * but that haven't been used.
>> -	 *
>> -	 * In fact on xen we mark RO the whole range pgt_buf_start -
>> -	 * pgt_buf_top, because we have to make sure that when
>> -	 * init_memory_mapping reaches the pagetable pages area, it maps
>> -	 * RO all the pagetable pages, including the ones that are beyond
>> -	 * pgt_buf_end at that time.
>> -	 */
>> -	if (!after_bootmem && pgt_buf_end > pgt_buf_start)
>> -		x86_init.mapping.pagetable_reserve(PFN_PHYS(pgt_buf_start),
>> -				PFN_PHYS(pgt_buf_end));
>> +	if (pgt_buf_end != pgt_buf_top)
>> +		printk(KERN_DEBUG "initial kernel pagetable allocation wasted %lx"
>> +				" pages\n", pgt_buf_top - pgt_buf_end);
>>  
>>  	if (!after_bootmem)
>>  		early_memtest(start, end);
>> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
>> index dc708dc..2004f1e 100644
>> --- a/arch/x86/xen/mmu.c
>> +++ b/arch/x86/xen/mmu.c
>> @@ -1153,20 +1153,6 @@ static void __init
>xen_pagetable_setup_start(pgd_t *base)
>>  {
>>  }
>>  
>> -static __init void xen_mapping_pagetable_reserve(u64 start, u64 end)
>> -{
>> -	/* reserve the range used */
>> -	native_pagetable_reserve(start, end);
>> -
>> -	/* set as RW the rest */
>> -	printk(KERN_DEBUG "xen: setting RW the range %llx - %llx\n", end,
>> -			PFN_PHYS(pgt_buf_top));
>> -	while (end < PFN_PHYS(pgt_buf_top)) {
>> -		make_lowmem_page_readwrite(__va(end));
>> -		end += PAGE_SIZE;
>> -	}
>> -}
>> -
>>  static void xen_post_allocator_init(void);
>>  
>>  static void __init xen_pagetable_setup_done(pgd_t *base)
>> @@ -1997,7 +1983,6 @@ static const struct pv_mmu_ops xen_mmu_ops
>__initconst = {
>>  
>>  void __init xen_init_mmu_ops(void)
>>  {
>> -	x86_init.mapping.pagetable_reserve = xen_mapping_pagetable_reserve;
>>  	x86_init.paging.pagetable_setup_start = xen_pagetable_setup_start;
>>  	x86_init.paging.pagetable_setup_done = xen_pagetable_setup_done;
>>  	pv_mmu_ops = xen_mmu_ops;
>> --
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