Re: [PATCH v2 4/4] xen-all: Pass max_ram_below_4g to xen_hvm_init.

[Don Slutz <dslutz@verizon.com>]

On 03/17/14 14:22, Don Slutz wrote:
> On 03/17/14 13:55, Stefano Stabellini wrote:
>> On Mon, 17 Mar 2014, Don Slutz wrote:
>>> On 03/16/14 12:10, Stefano Stabellini wrote:
>>>> On Tue, 11 Mar 2014, Don Slutz wrote:
>>>>> This is the xen part of "pc & q35: Add new object pc-memory-layout."
>>>>>
>>>>> Signed-off-by: Don Slutz<dslutz@verizon.com>
>>>>> ---
>>>>>    hw/i386/pc_piix.c    |  4 ++--
>>>>>    hw/i386/pc_q35.c     |  4 ++--
>>>>>    include/hw/xen/xen.h |  4 ++--
>>>>>    xen-all.c            | 41 ++++++++++++++++++++++-------------------
>>>>>    xen-stub.c           |  4 ++--
>>>>>    5 files changed, 30 insertions(+), 27 deletions(-)
>>>>>
>>>>> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
>>>>> index 964ea33..691fc5d 100644
>>>>> --- a/hw/i386/pc_piix.c
>>>>> +++ b/hw/i386/pc_piix.c
>>>>> @@ -131,8 +131,8 @@ static void pc_init1(QEMUMachineInitArgs *args,
>>>>>            below_4g_mem_size = args->ram_size;
>>>>>        }
>>>>>    -    if (xen_enabled() && xen_hvm_init(&below_4g_mem_size,
>>>>> &above_4g_mem_size,
>>>>> -                                      &ram_memory) != 0) {
>>>>> +    if (xen_enabled() && xen_hvm_init(max_ram_below_4g,
>>>>> &below_4g_mem_size,
>>>>> + &above_4g_mem_size, &ram_memory) !=
>>>>> 0) {
>>>>>            fprintf(stderr, "xen hardware virtual machine initialisation
>>>>> failed\n");
>>>>>            exit(1);
>>>>>        }
>>>>> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
>>>>> index c95e6e2..8e1c417 100644
>>>>> --- a/hw/i386/pc_q35.c
>>>>> +++ b/hw/i386/pc_q35.c
>>>>> @@ -120,8 +120,8 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
>>>>>            below_4g_mem_size = args->ram_size;
>>>>>        }
>>>>>    -    if (xen_enabled() && xen_hvm_init(&below_4g_mem_size,
>>>>> &above_4g_mem_size,
>>>>> -                                      &ram_memory) != 0) {
>>>>> +    if (xen_enabled() && xen_hvm_init(max_ram_below_4g,
>>>>> &below_4g_mem_size,
>>>>> + &above_4g_mem_size, &ram_memory) !=
>>>>> 0) {
>>>>>            fprintf(stderr, "xen hardware virtual machine initialisation
>>>>> failed\n");
>>>>>            exit(1);
>>>>>        }
>>>>> diff --git a/include/hw/xen/xen.h b/include/hw/xen/xen.h
>>>>> index 0769db2..fda559a 100644
>>>>> --- a/include/hw/xen/xen.h
>>>>> +++ b/include/hw/xen/xen.h
>>>>> @@ -41,8 +41,8 @@ int xen_init(QEMUMachine *machine);
>>>>>    void xenstore_store_pv_console_info(int i, struct CharDriverState *chr);
>>>>>      #if defined(NEED_CPU_H) && !defined(CONFIG_USER_ONLY)
>>>>> -int xen_hvm_init(ram_addr_t *below_4g_mem_size, ram_addr_t
>>>>> *above_4g_mem_size,
>>>>> -                 MemoryRegion **ram_memory);
>>>>> +int xen_hvm_init(ram_addr_t max_ram_below_4g, ram_addr_t
>>>>> *below_4g_mem_size,
>>>>> +                 ram_addr_t *above_4g_mem_size, MemoryRegion
>>>>> **ram_memory);
>>>>>    void xen_ram_alloc(ram_addr_t ram_addr, ram_addr_t size,
>>>>>                       struct MemoryRegion *mr);
>>>>>    void xen_modified_memory(ram_addr_t start, ram_addr_t length);
>>>>> diff --git a/xen-all.c b/xen-all.c
>>>>> index c64300c..48ba335 100644
>>>>> --- a/xen-all.c
>>>>> +++ b/xen-all.c
>>>>> @@ -155,32 +155,34 @@ qemu_irq *xen_interrupt_controller_init(void)
>>>>>      /* Memory Ops */
>>>>>    -static void xen_ram_init(ram_addr_t *below_4g_mem_size,
>>>>> +static void xen_ram_init(ram_addr_t ram_size, ram_addr_t
>>>>> max_ram_below_4g,
>>>>> +                         ram_addr_t *below_4g_mem_size,
>>>>>                             ram_addr_t *above_4g_mem_size,
>>>>> -                         ram_addr_t ram_size, MemoryRegion
>>>>> **ram_memory_p)
>>>>> +                         MemoryRegion **ram_memory_p)
>>>>>    {
>>>>>        MemoryRegion *sysmem = get_system_memory();
>>>>>        ram_addr_t block_len;
>>>>>    -    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;
>>>>> +    if (!max_ram_below_4g) {
>>>>> +        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 {
>>>>> +            *above_4g_mem_size = 0;
>>>>> +            *below_4g_mem_size = ram_size;
>>>>> +        }
>>>>> +    }
>>>> Instead of treating max_ram_below_4g as a special case, couldn't
>>>> initialize it to HVM_BELOW_4G_RAM_END?
>>> Since max_ram_below_4g is used and initialize in normal QEMU code
>>> where HVM_BELOW_4G_RAM_END is not defined, I do not see how to
>>> do this outside of this routine without adding a new routine for this.
>>   You can simply do this at the beginning of xen_ram_init:
>>
>> max_ram_below_4g = max_ram_below_4g ? max_ram_below_4g : HVM_BELOW_4G_RAM_END;
>>
>> my comment was about code readability, I didn't mean change any
>> functionalities.
>
> So the partial code delta:
>
>      MemoryRegion *sysmem = get_system_memory();
>      ram_addr_t block_len;
>
> -    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;
> -    }
> -    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;
> +    max_ram_below_4g = max_ram_below_4g ? max_ram_below_4g : HVM_BELOW_4G_RAM_END;
> +    if (ram_size >= max_ram_below_4g) {
> +        *above_4g_mem_size = ram_size - max_ram_below_4g;
> +        *below_4g_mem_size = max_ram_below_4g;
>      } 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, and keep a hole of
> +         * 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);
>
>
> Which does redo the calculation of above and below when max_ram_below_4g
> is set, is better for code readability.
>
> I am happy to send a v2 with this, just do not want to send too many versions.
>

That would be v3. :(

> -Don Slutz
>
>
>