Re: [Xen-devel] [PATCH 2.1 v7 3/3] xen-hvm: Handle machine opt max-ram-below-4g

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 19 Jun 2014, Don Slutz wrote:
> This is the xen part of "pc & q35: Add new machine opt max-ram-below-4g"
> 
> Note: this machine option cannot be used to increase the amount
> of ram below 4G.
> 
> Signed-off-by: Don Slutz <dslutz@xxxxxxxxxxx>

It is still good for me.

> v7:
>      Rename from "xen-hvm: Pass is_default to xen_hvm_init"
>      Drop is_default.
>      Use object_property_get_int() to get max-ram-below-4g.
>      Do min(xen limit, user limit).
> v6:
>     Changed to work with the changes in #2:
>       Added max_ram_below_4g_changed in order to know if it is a default value
>       or a user specified one.
>     Added "assert(pc_machine->max_ram_below_4g_changed > 0)" so that
>       "make check" will abort on default not set for any of the pc or
>       q35 machine types.
>     Dropped "Acked-by: Stefano Stabellin" do to bigger change.
> 
>  xen-hvm.c | 35 +++++++++++++++++++++++------------
>  1 file changed, 23 insertions(+), 12 deletions(-)
> 
> diff --git a/xen-hvm.c b/xen-hvm.c
> index a0b6b5d..2745a7a 100644
> --- a/xen-hvm.c
> +++ b/xen-hvm.c
> @@ -161,25 +161,36 @@ static void xen_ram_init(ram_addr_t *below_4g_mem_size,
>  {
>      MemoryRegion *sysmem = get_system_memory();
>      ram_addr_t block_len;
> +    uint64_t user_lowmem = object_property_get_int(qdev_get_machine(),
> +                                                   
> PC_MACHINE_MAX_RAM_BELOW_4G,
> +                                                   &error_abort);
>  
> -    block_len = 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
> -         */
> -        block_len += HVM_BELOW_4G_MMIO_LENGTH;
> +    /* Handle the machine opt max-ram-below-4g.  It is basicly doing
> +     * min(xen limit, user limit).
> +     */
> +    if (HVM_BELOW_4G_RAM_END <= user_lowmem) {
> +        user_lowmem = HVM_BELOW_4G_RAM_END;
>      }
> -    memory_region_init_ram(&ram_memory, NULL, "xen.ram", block_len);
> -    *ram_memory_p = &ram_memory;
> -    vmstate_register_ram_global(&ram_memory);
>  
> -    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;
> +    if (ram_size >= user_lowmem) {
> +        *above_4g_mem_size = ram_size - user_lowmem;
> +        *below_4g_mem_size = user_lowmem;
>      } else {
>          *above_4g_mem_size = 0;
>          *below_4g_mem_size = ram_size;
>      }
> +    if (!*above_4g_mem_size) {
> +        block_len = ram_size;
> +    } else {
> +        /*
> +         * Xen does not allocate the memory continuously, it keeps a
> +         * hole of the size computed above or passed in.
> +         */
> +        block_len = (1ULL << 32) + *above_4g_mem_size;
> +    }
> +    memory_region_init_ram(&ram_memory, NULL, "xen.ram", block_len);
> +    *ram_memory_p = &ram_memory;
> +    vmstate_register_ram_global(&ram_memory);
>  
>      memory_region_init_alias(&ram_640k, NULL, "xen.ram.640k",
>                               &ram_memory, 0, 0xa0000);
> -- 
> 1.8.4
> 

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