Re: [Qemu-devel] [PATCH 4/5] xen: Fix the memory registration to reflect of what is done by Xen.

[Paolo Bonzini <pbonzini@redhat.com>]

On 07/15/2011 04:32 PM, Anthony PERARD wrote:
> A Xen guest memory is allocated by libxc. But this memory is not
> allocated continuously, instead, it leaves the VGA IO memory space not
> allocated, same for the MMIO space (at HVM_BELOW_4G_MMIO_START of size
> HVM_BELOW_4G_MMIO_LENGTH).
>
> So to reflect that, we do not register the physical memory for this two
> holes. But we still keep only one RAMBlock for the all RAM as it is more
> easier than have two separate blocks (1 above 4G). Also this prevent QEMU
> from use the MMIO space for a ROM.
>
> Signed-off-by: Anthony PERARD<anthony.perard@citrix.com>
> ---
>   xen-all.c |   21 ++++++++++++++-------
>   1 files changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/xen-all.c b/xen-all.c
> index 2c0a62d..76d5c5c 100644
> --- a/xen-all.c
> +++ b/xen-all.c
> @@ -144,6 +144,12 @@ static void xen_ram_init(ram_addr_t ram_size)
>       new_block->host = NULL;
>       new_block->offset = 0;
>       new_block->length = ram_size;
> +    if (ram_size>= HVM_BELOW_4G_RAM_END) {
> +        /* Xen does not allocate the memory continuously, and keep a hole at
> +         * HVM_BELOW_4G_MMIO_START of HVM_BELOW_4G_MMIO_LENGTH
> +         */
> +        new_block->length += HVM_BELOW_4G_MMIO_LENGTH;
> +    }
>
>       QLIST_INSERT_HEAD(&ram_list.blocks, new_block, next);
>
> @@ -152,20 +158,21 @@ static void xen_ram_init(ram_addr_t ram_size)
>       memset(ram_list.phys_dirty + (new_block->offset>>  TARGET_PAGE_BITS),
>              0xff, new_block->length>>  TARGET_PAGE_BITS);
>
> -    if (ram_size>= 0xe0000000 ) {
> -        above_4g_mem_size = ram_size - 0xe0000000;
> -        below_4g_mem_size = 0xe0000000;
> +    if (ram_size>= HVM_BELOW_4G_RAM_END) {
> +        above_4g_mem_size = ram_size - HVM_BELOW_4G_RAM_END;
> +        below_4g_mem_size = HVM_BELOW_4G_RAM_END;
>       } else {
>           below_4g_mem_size = ram_size;
>       }
>
> -    cpu_register_physical_memory(0, below_4g_mem_size, new_block->offset);
> -#if TARGET_PHYS_ADDR_BITS>  32
> +    cpu_register_physical_memory(0, 0xa0000, 0);
> +    /* Skip of the VGA IO memory space */
> +    cpu_register_physical_memory(0xc0000, below_4g_mem_size - 0xc0000,
> +                                 0xc0000);
>       if (above_4g_mem_size>  0) {
>           cpu_register_physical_memory(0x100000000ULL, above_4g_mem_size,
> -                                     new_block->offset + below_4g_mem_size);
> +                                     0x100000000ULL);
>       }
> -#endif
>   }
>
>   void xen_ram_alloc(ram_addr_t ram_addr, ram_addr_t size)

Acked-by: Paolo Bonzini <pbonzini@redhat.com>

Paolo