Re: [PATCH] x86: don't blindly create L3 tables for the direct map

[Andrew Cooper <andrew.cooper3@citrix.com>]

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On 30/09/13 13:34, Jan Beulich wrote:
> Now that the direct map area can extend all the way up to almost the
> end of address space, this is wasteful.
>
> Also fold two almost redundant messages in SRAT parsing into one.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> Tested-by: Malcolm Crossley <malcolm.crossley@citrix.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

>
> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -137,7 +137,7 @@ l1_pgentry_t __attribute__ ((__section__
>  #define PTE_UPDATE_WITH_CMPXCHG
>  #endif
>  
> -bool_t __read_mostly mem_hotplug = 0;
> +paddr_t __read_mostly mem_hotplug;
>  
>  /* Private domain structs for DOMID_XEN and DOMID_IO. */
>  struct domain *dom_xen, *dom_io, *dom_cow;
> --- a/xen/arch/x86/srat.c
> +++ b/xen/arch/x86/srat.c
> @@ -113,6 +113,7 @@ static __init void bad_srat(void)
>  		apicid_to_node[i] = NUMA_NO_NODE;
>  	for (i = 0; i < ARRAY_SIZE(pxm2node); i++)
>  		pxm2node[i] = NUMA_NO_NODE;
> +	mem_hotplug = 0;
>  }
>  
>  /*
> @@ -257,13 +258,6 @@ acpi_numa_memory_affinity_init(struct ac
>  		return;
>  	}
>  	/* It is fine to add this area to the nodes data it will be used later*/
> -	if (ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE)
> -	{
> -		printk(KERN_INFO "SRAT: hot plug zone found %"PRIx64" - %"PRIx64" \n",
> -				start, end);
> -		mem_hotplug = 1;
> -	}
> -
>  	i = conflicting_memblks(start, end);
>  	if (i == node) {
>  		printk(KERN_WARNING
> @@ -287,8 +281,11 @@ acpi_numa_memory_affinity_init(struct ac
>  		if (nd->end < end)
>  			nd->end = end;
>  	}
> -	printk(KERN_INFO "SRAT: Node %u PXM %u %"PRIx64"-%"PRIx64"\n", node, pxm,
> -	       start, end);
> +	if ((ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) && end > mem_hotplug)
> +		mem_hotplug = end;
> +	printk(KERN_INFO "SRAT: Node %u PXM %u %"PRIx64"-%"PRIx64"%s\n",
> +	       node, pxm, start, end,
> +	       ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE ? " (hotplug)" : "");
>  
>  	node_memblk_range[num_node_memblks].start = start;
>  	node_memblk_range[num_node_memblks].end = end;
> --- a/xen/arch/x86/x86_64/mm.c
> +++ b/xen/arch/x86/x86_64/mm.c
> @@ -559,25 +559,20 @@ void __init paging_init(void)
>       * We setup the L3s for 1:1 mapping if host support memory hotplug
>       * to avoid sync the 1:1 mapping on page fault handler
>       */
> -    if ( mem_hotplug )
> +    for ( va = DIRECTMAP_VIRT_START;
> +          va < DIRECTMAP_VIRT_END && (void *)va < __va(mem_hotplug);
> +          va += (1UL << L4_PAGETABLE_SHIFT) )
>      {
> -        unsigned long va;
> -
> -        for ( va = DIRECTMAP_VIRT_START;
> -              va < DIRECTMAP_VIRT_END;
> -              va += (1UL << L4_PAGETABLE_SHIFT) )
> +        if ( !(l4e_get_flags(idle_pg_table[l4_table_offset(va)]) &
> +              _PAGE_PRESENT) )
>          {
> -            if ( !(l4e_get_flags(idle_pg_table[l4_table_offset(va)]) &
> -                  _PAGE_PRESENT) )
> -            {
> -                l3_pg = alloc_domheap_page(NULL, 0);
> -                if ( !l3_pg )
> -                    goto nomem;
> -                l3_ro_mpt = page_to_virt(l3_pg);
> -                clear_page(l3_ro_mpt);
> -                l4e_write(&idle_pg_table[l4_table_offset(va)],
> -                  l4e_from_page(l3_pg, __PAGE_HYPERVISOR));
> -            }
> +            l3_pg = alloc_domheap_page(NULL, 0);
> +            if ( !l3_pg )
> +                goto nomem;
> +            l3_ro_mpt = page_to_virt(l3_pg);
> +            clear_page(l3_ro_mpt);
> +            l4e_write(&idle_pg_table[l4_table_offset(va)],
> +                      l4e_from_page(l3_pg, __PAGE_HYPERVISOR));
>          }
>      }
>  
> --- a/xen/include/asm-x86/mm.h
> +++ b/xen/include/asm-x86/mm.h
> @@ -399,7 +399,7 @@ static inline int get_page_and_type(stru
>  int check_descriptor(const struct domain *, struct desc_struct *d);
>  
>  extern bool_t opt_allow_superpage;
> -extern bool_t mem_hotplug;
> +extern paddr_t mem_hotplug;
>  
>  /******************************************************************************
>   * With shadow pagetables, the different kinds of address start 
>
>
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel


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