This patch adds a virtual device to qemu which the uefi firmware can use to store variables. This moves the UEFI variable management from privileged guest code (managing vars in pflash) to the host. Main advantage is that the need to have privilege separation in the guest goes away.
On x86 privileged guest code runs in SMM. It's supported by kvm, but not liked much by various stakeholders in cloud space due to the complexity SMM emulation brings. On arm privileged guest code runs in el3 (aka secure world). This is not supported by kvm, which is unlikely to change anytime soon given that even el2 support (nested virt) is being worked on for years and is not yet in mainline. The design idea is to reuse the request serialization protocol edk2 uses for communication between SMM and non-SMM code, so large chunks of the edk2 variable driver stack can be used unmodified. Only the driver which traps into SMM mode must be replaced by a driver which talks to qemu instead. A edk2 test branch can be found here (build with "-D QEMU_PV_VARS=TRUE"). https://github.com/kraxel/edk2/commits/devel/secure-boot-external-vars The uefi-vars device re-implements the privileged edk2 protocols (i.e. the code running in SMM mode). v3 changes: - switch sysbus device variant to use the qemu platform bus. - misc minor changes. v2 changes: - fully implement authenticated variables. - various cleanups and fixes. enjoy & take care, Gerd Gerd Hoffmann (23): hw/uefi: add include/hw/uefi/var-service-api.h hw/uefi: add include/hw/uefi/var-service-edk2.h hw/uefi: add include/hw/uefi/var-service.h hw/uefi: add var-service-guid.c hw/uefi: add var-service-utils.c hw/uefi: add var-service-vars.c hw/uefi: add var-service-auth.c hw/uefi: add var-service-policy.c hw/uefi: add var-service-core.c hw/uefi: add var-service-pkcs7.c hw/uefi: add var-service-pkcs7-stub.c hw/uefi: add var-service-siglist.c hw/uefi: add var-service-json.c + qapi for NV vars. hw/uefi: add trace-events hw/uefi: add UEFI_VARS to Kconfig hw/uefi: add to meson hw/uefi: add uefi-vars-sysbus device hw/uefi-vars-sysbus: qemu platform bus support hw/uefi-vars-sysbus: allow for arm virt hw/uefi: add uefi-vars-isa device hw/uefi-vars-isa: add acpi device docs: add uefi variable service documentation hw/uefi: add MAINTAINERS entry include/hw/uefi/var-service-api.h | 43 ++ include/hw/uefi/var-service-edk2.h | 227 +++++++++ include/hw/uefi/var-service.h | 186 ++++++++ hw/arm/virt.c | 2 + hw/core/sysbus-fdt.c | 24 + hw/uefi/var-service-auth.c | 361 ++++++++++++++ hw/uefi/var-service-core.c | 237 ++++++++++ hw/uefi/var-service-guid.c | 99 ++++ hw/uefi/var-service-isa.c | 115 +++++ hw/uefi/var-service-json.c | 242 ++++++++++ hw/uefi/var-service-pkcs7-stub.c | 16 + hw/uefi/var-service-pkcs7.c | 436 +++++++++++++++++ hw/uefi/var-service-policy.c | 370 +++++++++++++++ hw/uefi/var-service-siglist.c | 212 +++++++++ hw/uefi/var-service-sysbus.c | 90 ++++ hw/uefi/var-service-utils.c | 241 ++++++++++ hw/uefi/var-service-vars.c | 725 +++++++++++++++++++++++++++++ MAINTAINERS | 6 + docs/devel/index-internals.rst | 1 + docs/devel/uefi-vars.rst | 66 +++ hw/Kconfig | 1 + hw/meson.build | 1 + hw/uefi/Kconfig | 9 + hw/uefi/LIMITATIONS.md | 7 + hw/uefi/meson.build | 24 + hw/uefi/trace-events | 17 + meson.build | 1 + qapi/meson.build | 1 + qapi/qapi-schema.json | 1 + qapi/uefi.json | 45 ++ 30 files changed, 3806 insertions(+) create mode 100644 include/hw/uefi/var-service-api.h create mode 100644 include/hw/uefi/var-service-edk2.h create mode 100644 include/hw/uefi/var-service.h create mode 100644 hw/uefi/var-service-auth.c create mode 100644 hw/uefi/var-service-core.c create mode 100644 hw/uefi/var-service-guid.c create mode 100644 hw/uefi/var-service-isa.c create mode 100644 hw/uefi/var-service-json.c create mode 100644 hw/uefi/var-service-pkcs7-stub.c create mode 100644 hw/uefi/var-service-pkcs7.c create mode 100644 hw/uefi/var-service-policy.c create mode 100644 hw/uefi/var-service-siglist.c create mode 100644 hw/uefi/var-service-sysbus.c create mode 100644 hw/uefi/var-service-utils.c create mode 100644 hw/uefi/var-service-vars.c create mode 100644 docs/devel/uefi-vars.rst create mode 100644 hw/uefi/Kconfig create mode 100644 hw/uefi/LIMITATIONS.md create mode 100644 hw/uefi/meson.build create mode 100644 hw/uefi/trace-events create mode 100644 qapi/uefi.json -- 2.48.1
