Re: [PATCH v5 5/6] hw/arm/virt: Improve high memory region address assignment

[Cornelia Huck]

On Wed, Oct 12 2022, Gavin Shan <gshan@redhat.com> wrote:

> There are three high memory regions, which are VIRT_HIGH_REDIST2,
> VIRT_HIGH_PCIE_ECAM and VIRT_HIGH_PCIE_MMIO. Their base addresses
> are floating on highest RAM address. However, they can be disabled
> in several cases.
>
> (1) One specific high memory region is disabled by developer by
>     toggling vms->highmem_{redists, ecam, mmio}.
>
> (2) VIRT_HIGH_PCIE_ECAM region is disabled on machine, which is
>     'virt-2.12' or ealier than it.
>
> (3) VIRT_HIGH_PCIE_ECAM region is disabled when firmware is loaded
>     on 32-bits system.
>
> (4) One specific high memory region is disabled when it breaks the
>     PA space limit.
>
> The current implementation of virt_set_memmap() isn't comprehensive
> because the space for one specific high memory region is always
> reserved from the PA space for case (1), (2) and (3). In the code,
> 'base' and 'vms->highest_gpa' are always increased for those three
> cases. It's unnecessary since the assigned space of the disabled
> high memory region won't be used afterwards.
>
> This improves the address assignment for those three high memory
> region by skipping the address assignment for one specific high
> memory region if it has been disabled in case (1), (2) and (3).
> 'vms->high_compact' is false for now, meaning that we don't have
> any behavior changes until it becomes configurable through property
> 'compact-highmem' in next patch.
>
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> Tested-by: Zhenyu Zhang <zhenyzha@redhat.com>
> ---
>  hw/arm/virt.c         | 23 +++++++++++++++--------
>  include/hw/arm/virt.h |  1 +
>  2 files changed, 16 insertions(+), 8 deletions(-)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>