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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86-64: don't use xmalloc_array() for allocation of the (per-CPU) IDTs
On 13/10/2011 13:14, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
>>>> On 13.10.11 at 11:34, Keir Fraser <keir@xxxxxxx> wrote:
>> Given our antipathy to the x86-32 hypervisor, and the fact that any
>> remaining users of it are unlikely to be running MP systems at all let alone
>> large MP systems, how about this cleanup patch?... (It looks quite confusing
>> as a patch, actually, but does the obvious thing).
>
> Looks good to me - I was actually considering to convert the x86-64
> code back to alloc_xenheap_pages() too (for we'll need to do that
> eventually anyway when we want to support more than 5Tb of memory)
> when I put together that earlier patch, but then refrained from doing so
> to keep the patch size down.
You mean there's a 5TB limit for alloc_domheap_pages() allocations??
I only switched to alloc_xenheap_pages() because it's safe for x86-32 too...
-- Keir
> Jan
>
>> x86: Simplify smpboot_alloc by merging x86-{32,64} code as far as possible.
>>
>> We still need one ifdef, as x86-32 does not have a compat_gdt_table.
>>
>> On x86-32 there is 1/2-page wastage due to allocating a whole page for
>> the per-CPU IDT, however we expect very few users of the x86-32
>> hypervisor. Those that cannot move to the 64-bit hypervisor are likely
>> using old single-processor systems or new single-procesor netbooks. On
>> UP and small MP systems, the wastage is insignificant.
>>
>> Signed-off-by: Keir Fraser <keir@xxxxxxx>
>> diff -r 1515484353c6 xen/arch/x86/smpboot.c
>> --- a/xen/arch/x86/smpboot.c Thu Oct 13 10:09:28 2011 +0200
>> +++ b/xen/arch/x86/smpboot.c Thu Oct 13 10:25:01 2011 +0100
>> @@ -640,21 +640,16 @@ static void cpu_smpboot_free(unsigned in
>> unsigned int order;
>>
>> order = get_order_from_pages(NR_RESERVED_GDT_PAGES);
>> + free_xenheap_pages(per_cpu(gdt_table, cpu), order);
>> + per_cpu(gdt_table, cpu) = NULL;
>> +
>> #ifdef __x86_64__
>> - if ( per_cpu(compat_gdt_table, cpu) )
>> - free_domheap_pages(virt_to_page(per_cpu(gdt_table, cpu)), order);
>> - if ( per_cpu(gdt_table, cpu) )
>> - free_domheap_pages(virt_to_page(per_cpu(compat_gdt_table, cpu)),
>> - order);
>> + free_xenheap_pages(per_cpu(compat_gdt_table, cpu), order);
>> per_cpu(compat_gdt_table, cpu) = NULL;
>> - order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables));
>> - if ( idt_tables[cpu] )
>> - free_domheap_pages(virt_to_page(idt_tables[cpu]), order);
>> -#else
>> - free_xenheap_pages(per_cpu(gdt_table, cpu), order);
>> - xfree(idt_tables[cpu]);
>> #endif
>> - per_cpu(gdt_table, cpu) = NULL;
>> +
>> + order = get_order_from_bytes(IDT_ENTRIES * sizeof(idt_entry_t));
>> + free_xenheap_pages(idt_tables[cpu], order);
>> idt_tables[cpu] = NULL;
>>
>> if ( stack_base[cpu] != NULL )
>> @@ -669,9 +664,6 @@ static int cpu_smpboot_alloc(unsigned in
>> {
>> unsigned int order;
>> struct desc_struct *gdt;
>> -#ifdef __x86_64__
>> - struct page_info *page;
>> -#endif
>>
>> stack_base[cpu] = alloc_xenheap_pages(STACK_ORDER, 0);
>> if ( stack_base[cpu] == NULL )
>> @@ -679,41 +671,28 @@ static int cpu_smpboot_alloc(unsigned in
>> memguard_guard_stack(stack_base[cpu]);
>>
>> order = get_order_from_pages(NR_RESERVED_GDT_PAGES);
>> -#ifdef __x86_64__
>> - page = alloc_domheap_pages(NULL, order,
>> - MEMF_node(cpu_to_node(cpu)));
>> - if ( !page )
>> + per_cpu(gdt_table, cpu) = gdt =
>> + alloc_xenheap_pages(order, MEMF_node(cpu_to_node(cpu)));
>> + if ( gdt == NULL )
>> goto oom;
>> - per_cpu(compat_gdt_table, cpu) = gdt = page_to_virt(page);
>> - memcpy(gdt, boot_cpu_compat_gdt_table,
>> - NR_RESERVED_GDT_PAGES * PAGE_SIZE);
>> - gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu;
>> - page = alloc_domheap_pages(NULL, order,
>> - MEMF_node(cpu_to_node(cpu)));
>> - if ( !page )
>> - goto oom;
>> - per_cpu(gdt_table, cpu) = gdt = page_to_virt(page);
>> - order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables));
>> - page = alloc_domheap_pages(NULL, order,
>> - MEMF_node(cpu_to_node(cpu)));
>> - if ( !page )
>> - goto oom;
>> - idt_tables[cpu] = page_to_virt(page);
>> -#else
>> - per_cpu(gdt_table, cpu) = gdt = alloc_xenheap_pages(order, 0);
>> - if ( !gdt )
>> - goto oom;
>> - idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES);
>> - if ( idt_tables[cpu] == NULL )
>> - goto oom;
>> -#endif
>> - memcpy(gdt, boot_cpu_gdt_table,
>> - NR_RESERVED_GDT_PAGES * PAGE_SIZE);
>> + memcpy(gdt, boot_cpu_gdt_table, NR_RESERVED_GDT_PAGES * PAGE_SIZE);
>> BUILD_BUG_ON(NR_CPUS > 0x10000);
>> gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu;
>>
>> - memcpy(idt_tables[cpu], idt_table,
>> - IDT_ENTRIES*sizeof(idt_entry_t));
>> +#ifdef __x86_64__
>> + per_cpu(compat_gdt_table, cpu) = gdt =
>> + alloc_xenheap_pages(order, MEMF_node(cpu_to_node(cpu)));
>> + if ( gdt == NULL )
>> + goto oom;
>> + memcpy(gdt, boot_cpu_compat_gdt_table, NR_RESERVED_GDT_PAGES *
>> PAGE_SIZE);
>> + gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu;
>> +#endif
>> +
>> + order = get_order_from_bytes(IDT_ENTRIES * sizeof(idt_entry_t));
>> + idt_tables[cpu] = alloc_xenheap_pages(order,
>> MEMF_node(cpu_to_node(cpu)));
>> + if ( idt_tables[cpu] == NULL )
>> + goto oom;
>> + memcpy(idt_tables[cpu], idt_table, IDT_ENTRIES * sizeof(idt_entry_t));
>>
>> return 0;
>>
>>
>>> Anyway, despite all this...
>>>
>>>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>>>
>>> Acked-by: Keir Fraser <keir@xxxxxxx>
>>>
>>>> --- a/xen/arch/x86/smpboot.c
>>>> +++ b/xen/arch/x86/smpboot.c
>>>> @@ -639,9 +639,6 @@ static void cpu_smpboot_free(unsigned in
>>>> {
>>>> unsigned int order;
>>>>
>>>> - xfree(idt_tables[cpu]);
>>>> - idt_tables[cpu] = NULL;
>>>> -
>>>> order = get_order_from_pages(NR_RESERVED_GDT_PAGES);
>>>> #ifdef __x86_64__
>>>> if ( per_cpu(compat_gdt_table, cpu) )
>>>> @@ -650,10 +647,15 @@ static void cpu_smpboot_free(unsigned in
>>>> free_domheap_pages(virt_to_page(per_cpu(compat_gdt_table, cpu)),
>>>> order);
>>>> per_cpu(compat_gdt_table, cpu) = NULL;
>>>> + order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables));
>>>> + if ( idt_tables[cpu] )
>>>> + free_domheap_pages(virt_to_page(idt_tables[cpu]), order);
>>>> #else
>>>> free_xenheap_pages(per_cpu(gdt_table, cpu), order);
>>>> + xfree(idt_tables[cpu]);
>>>> #endif
>>>> per_cpu(gdt_table, cpu) = NULL;
>>>> + idt_tables[cpu] = NULL;
>>>>
>>>> if ( stack_base[cpu] != NULL )
>>>> {
>>>> @@ -691,19 +693,25 @@ static int cpu_smpboot_alloc(unsigned in
>>>> if ( !page )
>>>> goto oom;
>>>> per_cpu(gdt_table, cpu) = gdt = page_to_virt(page);
>>>> + order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables));
>>>> + page = alloc_domheap_pages(NULL, order,
>>>> + MEMF_node(cpu_to_node(cpu)));
>>>> + if ( !page )
>>>> + goto oom;
>>>> + idt_tables[cpu] = page_to_virt(page);
>>>> #else
>>>> per_cpu(gdt_table, cpu) = gdt = alloc_xenheap_pages(order, 0);
>>>> if ( !gdt )
>>>> goto oom;
>>>> + idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES);
>>>> + if ( idt_tables[cpu] == NULL )
>>>> + goto oom;
>>>> #endif
>>>> memcpy(gdt, boot_cpu_gdt_table,
>>>> NR_RESERVED_GDT_PAGES * PAGE_SIZE);
>>>> BUILD_BUG_ON(NR_CPUS > 0x10000);
>>>> gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu;
>>>>
>>>> - idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES);
>>>> - if ( idt_tables[cpu] == NULL )
>>>> - goto oom;
>>>> memcpy(idt_tables[cpu], idt_table,
>>>> IDT_ENTRIES*sizeof(idt_entry_t));
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Xen-devel mailing list
>>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>>> http://lists.xensource.com/xen-devel
>>>
>>>
>
>
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