Re: [PATCH v6 08/10] i386/pc: factor out device_memory base/size to helper

[Igor Mammedov <imammedo@redhat.com>]

On Fri,  1 Jul 2022 17:10:12 +0100
Joao Martins <joao.m.martins@oracle.com> wrote:

> Move obtaining hole64_start from device_memory MR base/size into an helper
> alongside correspondent getters in pc_memory_init() when the hotplug
> range is unitialized.
> 
> This is the final step that allows pc_pci_hole64_start() to be callable
> at the beginning of pc_memory_init() before any MRs are initialized.
> 
> Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> ---
>  hw/i386/pc.c | 55 +++++++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 41 insertions(+), 14 deletions(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index d6dff71012ab..a79fa1b6beeb 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -825,16 +825,48 @@ static hwaddr pc_above_4g_end(PCMachineState *pcms)
>      return x86ms->above_4g_mem_start + x86ms->above_4g_mem_size;
>  }
>  
> +static void pc_get_device_memory_range(PCMachineState *pcms,
> +                                       hwaddr *base,
> +                                       ram_addr_t *device_mem_size)
> +{
> +    PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
> +    MachineState *machine = MACHINE(pcms);
> +    ram_addr_t size;
> +    hwaddr addr;
> +

> +    if (pcmc->has_reserved_memory &&
> +        machine->device_memory && machine->device_memory->base) {
> +        *base = machine->device_memory->base;
> +        *device_mem_size = memory_region_size(&machine->device_memory->mr);
> +        return;
> +    }
is this block really needed?
(i.e. shouldn't block bellow always yeld the same result
as block above?)

> +
> +    /* handles uninitialized @device_memory MR */
> +    size = machine->maxram_size - machine->ram_size;
> +    addr = ROUND_UP(pc_above_4g_end(pcms), 1 * GiB);
> +
> +    if (pcmc->enforce_aligned_dimm) {
> +        /* size device region assuming 1G page max alignment per slot */
> +        size += (1 * GiB) * machine->ram_slots;
> +    }
> +
> +    *base = addr;
> +    *device_mem_size = size;
> +}
> +
> +
>  static uint64_t pc_get_cxl_range_start(PCMachineState *pcms)
>  {
>      PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
>      MachineState *machine = MACHINE(pcms);
>      hwaddr cxl_base;
> +    ram_addr_t size;
>  
> -    if (pcmc->has_reserved_memory && machine->device_memory->base) {
> -        cxl_base = machine->device_memory->base;
> +    if (pcmc->has_reserved_memory &&
> +        machine->device_memory && machine->device_memory->base) {
> +        pc_get_device_memory_range(pcms, &cxl_base, &size);
>          if (!pcmc->broken_reserved_end) {
> -            cxl_base += memory_region_size(&machine->device_memory->mr);
> +            cxl_base += size;
>          }
>      } else {
>          cxl_base = pc_above_4g_end(pcms);
> @@ -937,7 +969,7 @@ void pc_memory_init(PCMachineState *pcms,
>      /* initialize device memory address space */
>      if (pcmc->has_reserved_memory &&
>          (machine->ram_size < machine->maxram_size)) {
> -        ram_addr_t device_mem_size = machine->maxram_size - machine->ram_size;
> +        ram_addr_t device_mem_size;
>  
>          if (machine->ram_slots > ACPI_MAX_RAM_SLOTS) {
>              error_report("unsupported amount of memory slots: %"PRIu64,
> @@ -952,13 +984,7 @@ void pc_memory_init(PCMachineState *pcms,
>              exit(EXIT_FAILURE);
>          }
>  
> -        machine->device_memory->base =
> -            ROUND_UP(pc_above_4g_end(pcms), 1 * GiB);
> -
> -        if (pcmc->enforce_aligned_dimm) {
> -            /* size device region assuming 1G page max alignment per slot */
> -            device_mem_size += (1 * GiB) * machine->ram_slots;
> -        }
> +        pc_get_device_memory_range(pcms, &machine->device_memory->base, &device_mem_size);
>  
>          if ((machine->device_memory->base + device_mem_size) <
>              device_mem_size) {
> @@ -1063,13 +1089,14 @@ uint64_t pc_pci_hole64_start(void)
>      PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
>      MachineState *ms = MACHINE(pcms);
>      uint64_t hole64_start = 0;
> +    ram_addr_t size = 0;
>  
>      if (pcms->cxl_devices_state.is_enabled) {
>          hole64_start = pc_get_cxl_range_end(pcms);
> -    } else if (pcmc->has_reserved_memory && ms->device_memory->base) {
> -        hole64_start = ms->device_memory->base;
> +    } else if (pcmc->has_reserved_memory && (ms->ram_size < ms->maxram_size)) {
> +        pc_get_device_memory_range(pcms, &hole64_start, &size);
>          if (!pcmc->broken_reserved_end) {
> -            hole64_start += memory_region_size(&ms->device_memory->mr);
> +            hole64_start += size;
>          }
>      } else {
>          hole64_start = pc_above_4g_end(pcms);