46cd2c1050f0 ("hw/tpm: add PPI support to tpm-tis-device for ARM64
virt") unconditionally registers a "tpm-ppi" RAMBlock when the TPM
TIS sysbus device is realized. This breaks backward migration: a
QEMU with PPI support cannot migrate to an older QEMU without it:
Unknown ramblock "tpm-ppi", cannot accept migration
The failure is 100% reproducible on any aarch64 guest that uses
tpm-tis-device when migrating to a host whose QEMU predates the PPI
commit.
Fix by gating the PPI memory region behind a new "ppi" device
property, and disabling it via hw_compat_11_0[] for machine types
<= virt-11.0. Also move the sysbus_init_mmio() calls from
instance_init to realizefn so the memory regions are properly
initialized before being registered (Peter).
Not exposing the 2nd MMIO slot when ppi=off triggers a NULL
dereference in platform_bus_get_mmio_addr(), so patch 1 adds a
guard first.
Changes in v3:
- Reordered: platform-bus NULL guard is now patch 1 (Peter)
Changes in v2:
- Dropped zero-size memory region hack (Peter)
- Moved sysbus_init_mmio() from initfn to realizefn (Peter)
- Only expose PPI MMIO region when ppi=on (Peter)
- Added NULL guard in platform_bus_get_mmio_addr() (found via testing)
- v1:
https://lore.kernel.org/qemu-devel/[email protected]
- v2:
https://lore.kernel.org/qemu-devel/[email protected]
Signed-off-by: Mohammadfaiz Bawa <[email protected]>
Mohammadfaiz Bawa (3):
hw/core/platform-bus: guard platform_bus_get_mmio_addr() against NULL
hw/tpm: gate PPI support on tpm-tis-device behind a device property
hw/core/machine: disable tpm-tis-device PPI for machine type <= 11.0
hw/core/machine.c | 1 +
hw/core/platform-bus.c | 3 +--
hw/tpm/tpm_tis.h | 1 +
hw/tpm/tpm_tis_sysbus.c | 18 +++++++++++-------
4 files changed, 14 insertions(+), 9 deletions(-)
--
2.54.0
