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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 13.10.11 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.
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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