Re: [Xen-devel] [PATCH v2 03/23] acpi/hvmloader: Initialize vm_gid data outside ACPI code

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.08.16 at 23:06, <boris.ostrovsky@xxxxxxxxxx> wrote:
> --- a/tools/firmware/hvmloader/acpi/build.c
> +++ b/tools/firmware/hvmloader/acpi/build.c
> @@ -462,32 +462,26 @@ static int construct_secondary_tables(unsigned long 
> *table_ptrs,
>   *
>   * Return 0 if memory failure, != 0 if success
>   */
> -static int new_vm_gid(struct acpi_info *acpi_info)
> +static int new_vm_gid(struct acpi_config *config,
> +                      struct acpi_info *info)
>  {
> -    uint64_t vm_gid[2], *buf;
> -    const char * s;
> -    char *end;
> -
> -    acpi_info->vm_gid_addr = 0;
> -
> -    /* read ID and check for 0 */
> -    s = xenstore_read("platform/generation-id", "0:0");
> -    vm_gid[0] = strtoll(s, &end, 0);
> -    vm_gid[1] = 0;
> -    if ( end && end[0] == ':' )
> -        vm_gid[1] = strtoll(end+1, NULL, 0);
> -    if ( !vm_gid[0] && !vm_gid[1] )
> +    uint64_t *buf;
> +
> +    info->vm_gid_addr = 0;
> +
> +    /* check for 0 ID*/
> +    if ( !config->vm_gid[0] && !config->vm_gid[1] )
>          return 1;
>  
>      /* copy to allocate BIOS memory */
> -    buf = (uint64_t *) mem_alloc(sizeof(vm_gid), 8);
> +    buf = mem_alloc(sizeof(config->vm_gid), 8);
>      if ( !buf )
>          return 0;
> -    memcpy(buf, vm_gid, sizeof(vm_gid));
> +    memcpy(buf, config->vm_gid, sizeof(config->vm_gid));
>  
> -    /* set into ACPI table and HVM param the address */
> -    acpi_info->vm_gid_addr = virt_to_phys(buf);
> -    hvm_param_set(HVM_PARAM_VM_GENERATION_ID_ADDR, acpi_info->vm_gid_addr);
> +    /* set the address into ACPI table and also pass it back to the caller */
> +    info->vm_gid_addr = virt_to_phys(buf);

What consumer of this value is left? Can't that field go away now?

> +    config->vm_gid_addr = virt_to_phys(buf);

If it can't, and considering that virt_to_phys() is going to become a
function call, the second initialization would better use the first one's
result. 

Jan


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