Re: [RFC PATCH] xen/arm: Introduce GICV3 Self Tests

[Ayan Kumar Halder <ayankuma@xxxxxxx>]

On 16/09/2025 11:55, Grygorii Strashko wrote:
> Hi Ayan,
Hi Grygorii,
> On 12.09.25 20:00, Ayan Kumar Halder wrote:
> > Introduce CONFIG_GICV3_SELFTEST to enclose tests for GICv3 driver.
> > Test that Xen is able to generate SGIs.
> >
> > Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
> > ---
> > One of the aim of functional safety is to test hw/sw interface. This 
> > means that
> > Xen is able to configure the hardware correctly for the desired 
> > functionalities.
> > Normally this is tested from the VMs. For eg if a VM is able to 
> > receive irq, this
> > implies that Xen has configured the GICv3 interface 'correctly'. 
> > However this is
> > a high level (or integration) test which uses not only the GICv3 
> > interface
> > between Xen and VM, but the interrupt injection code for Xen to VMs.
> >
> > We want to have some kind of unit tests to check that Xen is able to 
> > receive
> > various interrupts, set priorities, etc. Here, we have written unit 
> > tests for
> > software generated interrupts (SGIs) as example.
> >
> > These tests are expected to be triggered as Xen boots (right after 
> > Xen has
> > initialised the GICv3 interface ie gicv3_init(). The aim of this test 
> > is to
> > check whether Xen can trigger SGIs after gicv3_init() is invoked. If 
> > so, we can
> > claim that gicv3_init() was done properly to be able to trigger SGIs. 
> > Likewise
> > we will have tests to check for priorities, SPIs, etc.
> >
> > A script will parse the logs and claim that Xen is able to trigger SGIs.
> >
> >   xen/arch/arm/Kconfig  |  8 ++++++++
> >   xen/arch/arm/gic-v3.c |  7 +++++++
> >   xen/arch/arm/gic.c    | 21 +++++++++++++++++++++
> >   3 files changed, 36 insertions(+)
> >
> > diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
> > index 950e4452c1..739f99eaa9 100644
> > --- a/xen/arch/arm/Kconfig
> > +++ b/xen/arch/arm/Kconfig
> > @@ -73,6 +73,14 @@ config GICV3
> >         Driver for the ARM Generic Interrupt Controller v3.
> >         If unsure, use the default setting.
> >   +config GICV3_SELFTEST
> > +    bool "GICv3 driver self test"
> > +    default n
> > +    depends on GICV3
> > +    ---help---
> > +
> > +      Self tests to validate GICV3 driver.
> > +
> >   config HAS_ITS
> >           bool "GICv3 ITS MSI controller support (UNSUPPORTED)" if 
> > UNSUPPORTED
> >           depends on GICV3 && !NEW_VGIC && !ARM_32
> > diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
> > index 4e6c98bada..eb0c05231c 100644
> > --- a/xen/arch/arm/gic-v3.c
> > +++ b/xen/arch/arm/gic-v3.c
> > @@ -1818,6 +1818,13 @@ static int __init gicv3_init(void)
> >         gicv3_hyp_init();
> >   +#ifdef CONFIG_GICV3_SELFTEST
> > +    send_SGI_self(GIC_SGI_EVENT_CHECK);
> > +    send_SGI_self(GIC_SGI_DUMP_STATE);
> > +    send_SGI_self(GIC_SGI_CALL_FUNCTION);
> > +    send_SGI_self(GIC_SGI_MAX);
> > +#endif
> > +
> I'd like to ask, if possible, to minimize mixing selftest and 
> functional code.
> Like add gic-v3-selftest.c.
I can try that. However, the self test needs to be invoked from 
functional code.
Also, your suggestion gave me an idea. I can do :-

+static bool __initdata opt_gicv3_selftest = false;
+
+#ifdef CONFIG_GICV3_SELFTEST
+opt_gicv3_selftest = true;
+#endif

> >   out:
> >       spin_unlock(&gicv3.lock);
> >   diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
> > index d922ea67aa..5cb58cdb92 100644
> > --- a/xen/arch/arm/gic.c
> > +++ b/xen/arch/arm/gic.c
> > @@ -346,6 +346,26 @@ static void do_sgi(struct cpu_user_regs *regs, 
> > enum gic_sgi sgi)
> >        */
> >       smp_rmb();
> >   +#ifdef CONFIG_GICV3_SELFTEST
> if (gic_selftest_run)
And then instead of ifdef, I can enclose the below under "if 
(gicv3_selftest)" .
> > +    switch (sgi)
> > +    {
> > +    case GIC_SGI_EVENT_CHECK:
> > +        printk("GIC_SGI_EVENT_CHECK received\n");
> > +        break;
> > +    case GIC_SGI_DUMP_STATE:
> > +        printk("GIC_SGI_DUMP_STATE received\n");
> > +        break;
> > +    case GIC_SGI_CALL_FUNCTION:
> > +        printk("GIC_SGI_CALL_FUNCTION received\n");
> > +        break;
> > +    case GIC_SGI_MAX:
> > +        printk("GIC_SGI_MAX received\n");
>        gic_selftest_done = true;
>
> > +        break;
> > +    default:
> > +        panic("Unknown SGI triggered\n");
> > +        break;
> > +    }
> Potentially GIC selftest code can be guarded by some 
> "gic_selftest_run/done" vars
> if xen boot is expected to proceed further after testing.
Ah no, Xen will terminate after running the self test.

- Ayan