ACPI: Build Hardware Error Source Table

ACPI: Build Hardware Error Source Table

This patch builds Hardware Error Source Table(HEST) via fw_cfg blobs.
Now it only supports ARMv8 SEA, a type of Generic Hardware Error
Source version 2(GHESv2) error source. Afterwards, we can extend
the supported types if needed. For the CPER section, currently it
is memory section because kernel mainly wants userspace to handle
the memory errors.

This patch follows the spec ACPI 6.2 to build the Hardware Error
Source table. For more detailed information, please refer to
document: docs/specs/acpi_hest_ghes.rst

build_ghes_hw_error_notification() helper will help to add Hardware
Error Notification to ACPI tables without using packed C structures
and avoid endianness issues as API doesn't need explicit conversion.

Signed-off-by: Xiang Zheng <zhengxiang9@huawei.com>
Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-id: 20200512030609.19593-6-gengdongjiu@huawei.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>