On Wed, 21 Jan 2026 at 13:41, Mohamed Mediouni <[email protected]> wrote:
>
> Introduce a -M msi= argument to be able to control MSI-X support independently
> from ITS, as part of supporting GICv3 + GICv2m platforms.
>
> Remove vms->its as it's no longer needed after that change.
>
> Signed-off-by: Mohamed Mediouni <[email protected]>
> ---
> hw/arm/virt-acpi-build.c | 27 ++++++--
> hw/arm/virt.c | 137 +++++++++++++++++++++++++++++++++++++--
> include/hw/arm/virt.h | 8 ++-
> 3 files changed, 157 insertions(+), 15 deletions(-)
>
> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index 03b4342574..187dd4e272 100644
> --- a/hw/arm/virt-acpi-build.c
> +++ b/hw/arm/virt-acpi-build.c
> @@ -440,6 +440,17 @@ static void create_rc_its_idmaps(GArray *its_idmaps,
> GArray *smmuv3_devs)
> }
> }
>
> +/*
> + * In the prior Qemu ACPI table handling, GICv2 configurations
> + * had vms->its=1... That's broken.
> + *
> + * Match that assumption to match the existing ACPI tables that
> + * have been shipping for quite a while.
> + */
> +static int is_gicv2_acpi_workaround_needed(VirtMachineState *vms) {
> + return vms->gic_version == 2;
> +}
We don't need to keep identical bug-for-bug ACPI tables like that.
If we were incorrectly reporting an ITS in a GICv2-only ACPI table,
that was a bug and we can fix it. (This might need adjusting of the
golden reference ACPI data in some of the bios-tables-tests if we
were testing that, so it ought to go in its own patch.)
> +bool virt_is_its_enabled(VirtMachineState *vms)
> +{
> + switch (vms->msi_controller) {
> + case VIRT_MSI_CTRL_NONE:
> + return false;
> + case VIRT_MSI_CTRL_ITS:
> + return true;
> + case VIRT_MSI_CTRL_GICV2M:
> + return false;
> + case VIRT_MSI_CTRL_AUTO:
> + /*
> + * Earlier Qemu considered its=on as the default when using the
> GICv2.
> + * It is safe to do this because this is called is prior to
> + * finalize_msi_controller.
> + */
> + return true;
> + default:
> + g_assert_not_reached();
> + }
> +}
> +
> +bool virt_is_gicv2m_enabled(VirtMachineState *vms)
> +{
> + switch (vms->msi_controller) {
> + case VIRT_MSI_CTRL_NONE:
> + return false;
> + case VIRT_MSI_CTRL_ITS:
> + case VIRT_MSI_CTRL_GICV2M:
> + case VIRT_MSI_CTRL_AUTO:
> + return !virt_is_its_enabled(vms);
> + default:
> + g_assert_not_reached();
> + }
> +}
Why do we need these? The idea of finalize_msi_controller()
is that it fixes vms->msi_controller so that you can just
directly say vms->msi_controller == VIRT_MSI_CTRL_ITS or
vms->msi_controller == VIRT_MSI_CTRL_GICV2M rather than
having to have more complicated logic.
thanks
-- PMM
