On Thu, 30 Jun 2022 at 11:39, Jason A. Donenfeld <ja...@zx2c4.com> wrote:
>
> In 60592cfed2 ("hw/arm/virt: dt: add kaslr-seed property"), the
> kaslr-seed property was added, but the equally as important rng-seed
> property was forgotten about, which has identical semantics for a
> similar purpose. This commit implements it in exactly the same way as
> kaslr-seed. It then changes the name of the disabling option to reflect
> that this has more to do with randomness vs determinism, rather than
> something particular about kaslr.
>
> Cc: Peter Maydell <peter.mayd...@linaro.org>
> Signed-off-by: Jason A. Donenfeld <ja...@zx2c4.com>Thanks for this respin; I think this is the right way to go. > --- > docs/system/arm/virt.rst | 17 ++++++++++------ > hw/arm/virt.c | 44 ++++++++++++++++++++++++---------------- > include/hw/arm/virt.h | 2 +- > 3 files changed, 39 insertions(+), 24 deletions(-) > > diff --git a/docs/system/arm/virt.rst b/docs/system/arm/virt.rst > index 3d1058a80c..3b6ba69a9a 100644 > --- a/docs/system/arm/virt.rst > +++ b/docs/system/arm/virt.rst > @@ -126,13 +126,18 @@ ras > Set ``on``/``off`` to enable/disable reporting host memory errors to a > guest > using ACPI and guest external abort exceptions. The default is off. > > +dtb-randomness > + Set ``on``/``off`` to pass random seeds via the guest DTB > + rng-seed and kaslr-seed nodes (in both "/chosen" and > + "/secure-chosen") to use for features like the random number > + generator and address space randomisation. The default is > + ``on``. You will want to disable it if your trusted boot chain > + will verify the DTB it is passed, since this option causes the > + DTB to be non-deterministic. It would be the responsibility of > + the firmware to come up with a seed and pass it on if it wants to. > + > dtb-kaslr-seed > - Set ``on``/``off`` to pass a random seed via the guest dtb > - kaslr-seed node (in both "/chosen" and /secure-chosen) to use > - for features like address space randomisation. The default is > - ``on``. You will want to disable it if your trusted boot chain will > - verify the DTB it is passed. It would be the responsibility of the > - firmware to come up with a seed and pass it on if it wants to. > + A deprecated synonym for dtb-randomness. We should also add a section to docs/about/deprecated.rst noting that the old name is deprecated in favour of the new one. I'll fold that in when I add the patch to target-arm.next, to save you doing a respin: --- a/docs/about/deprecated.rst +++ b/docs/about/deprecated.rst @@ -225,6 +225,14 @@ Use the more generic event ``DEVICE_UNPLUG_GUEST_ERROR`` instead. System emulator machines ------------------------ +Arm ``virt`` machine ``dtb-kaslr-seed`` property +'''''''''''''''''''''''''''''''''''''''''''''''' + +The ``dtb-kaslr-seed`` property on the ``virt`` board has been +deprecated; use the new name ``dtb-randomness`` instead. The new name +better reflects the way this property affects all random data within +the device tree blob, not just the ``kaslr-seed`` node. + > + object_class_property_add_bool(oc, "dtb-randomness", > + virt_get_dtb_randomness, > + virt_set_dtb_randomness); > + object_class_property_set_description(oc, "dtb-randomness", > + "Set off to disable passing random > or " > + "non-deterministic dtb nodes to > guest"); > + > object_class_property_add_bool(oc, "dtb-kaslr-seed", > - virt_get_dtb_kaslr_seed, > - virt_set_dtb_kaslr_seed); > + virt_get_dtb_randomness, > + virt_set_dtb_randomness); > object_class_property_set_description(oc, "dtb-kaslr-seed", > - "Set off to disable passing of > kaslr-seed " > - "dtb node to guest"); > + "Deprecated synonym of > dtb-randomness"); I was going to suggest object_property_add_alias() but that works at the object level, not the class level, so never mind. This will work, and eventually we'll delete the code when it hits the deprecation-to-removal horizon. So Reviewed-by: Peter Maydell <peter.mayd...@linaro.org> and applied to target-arm.next. thanks -- PMM
