On 10/25/22 12:30, Cornelia Huck wrote:
> On Mon, Oct 24 2022, Gavin Shan <gs...@redhat.com> wrote:
>
>> After the improvement to high memory region address assignment is
>> applied, the memory layout can be changed, introducing possible
>> migration breakage. For example, VIRT_HIGH_PCIE_MMIO memory region
>> is disabled or enabled when the optimization is applied or not, with
>> the following configuration. The configuration is only achievable by
>> modifying the source code until more properties are added to allow
>> users selectively disable those high memory regions.
>>
>> pa_bits = 40;
>> vms->highmem_redists = false;
>> vms->highmem_ecam = false;
>> vms->highmem_mmio = true;
>>
>> # qemu-system-aarch64 -accel kvm -cpu host \
>> -machine virt-7.2,compact-highmem={on, off} \
>> -m 4G,maxmem=511G -monitor stdio
>>
>> Region compact-highmem=off compact-highmem=on
>> ----------------------------------------------------------------
>> MEM [1GB 512GB] [1GB 512GB]
>> HIGH_GIC_REDISTS2 [512GB 512GB+64MB] [disabled]
>> HIGH_PCIE_ECAM [512GB+256MB 512GB+512MB] [disabled]
>> HIGH_PCIE_MMIO [disabled] [512GB 1TB]
>>
>> In order to keep backwords compatibility, we need to disable the
>> optimization on machine, which is virt-7.1 or ealier than it. It
>> means the optimization is enabled by default from virt-7.2. Besides,
>> 'compact-highmem' property is added so that the optimization can be
>> explicitly enabled or disabled on all machine types by users.
>>
>> Signed-off-by: Gavin Shan <gs...@redhat.com>
>> Reviewed-by: Cornelia Huck <coh...@redhat.com>
>> Tested-by: Zhenyu Zhang <zheny...@redhat.com>
>> ---
>> docs/system/arm/virt.rst | 4 ++++
>> hw/arm/virt.c | 32 ++++++++++++++++++++++++++++++++
>> include/hw/arm/virt.h | 1 +
>> 3 files changed, 37 insertions(+)
>>
> (...)
>
>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>> index 4896f600b4..11b5685432 100644
>> --- a/hw/arm/virt.c
>> +++ b/hw/arm/virt.c
>> @@ -174,6 +174,12 @@ static const MemMapEntry base_memmap[] = {
>> * Note the extended_memmap is sized so that it eventually also includes the
>> * base_memmap entries (VIRT_HIGH_GIC_REDIST2 index is greater than the last
>> * index of base_memmap).
>> + *
>> + * The memory map for these Highmem IO Regions can be in legacy or compact
>> + * layout, depending on 'compact-highmem' property. With legacy layout, the
>> + * PA space for one specific region is always reserved, even the region has
> s/even/even if/
Reviewed-by: Eric Auger <eric.au...@redhat.com>
Thanks
Eric
>
>> + * been disabled or doesn't fit into the PA space. However, the PA space for
>> + * the region won't be reserved in these circumstances with compact layout.
>> */
>> static MemMapEntry extended_memmap[] = {
>> /* Additional 64 MB redist region (can contain up to 512
>> redistributors) */
