Re: [PATCH 5/6] xen/arm: Add function to query IRQ 'ownership'

[Julien Grall <julien.grall@arm.com>]

Hello,

On 06/04/2017 20:47, Chris Patterson wrote:
> From: "Chris Patterson" <pattersonc@ainfosec.com>
>
> The addition of new IRQ-related platform hooks now allow platforms to
> perform platform-specific interrupt logic, such as allowing virtualization
> of platform-specific interrupt controller hardware.
>
> This commit adds the ability for the platform to identify the domain
> a given IRQ is routed to, allowing platform logic to deny access to
> registers associated with a given IRQ unless the requesting domain
> 'owns' the IRQ. This will be used on Tegra platforms, where the hardware
> domain needs access to its legacy interrupt controller, but should not
> be able to control registers that correspond to other domains' IRQs, or
> sections associated with IRQs routed to Xen.
>
> Authored-by: Kyle Temkin <temkink@ainfosec.com>
> Signed-off-by: Kyle Temkin <temkink@ainfosec.com>
> Signed-off-by: Chris Patterson <pattersonc@ainfosec.com>
> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> ---
>
> changes since rfc:
> - formatting & code style cleanup
>
> ---
>
>  xen/arch/arm/irq.c        | 10 ++++++++++
>  xen/include/asm-arm/irq.h |  2 ++
>  2 files changed, 12 insertions(+)
>
> diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
> index 0b4eaa9..51bce58 100644
> --- a/xen/arch/arm/irq.c
> +++ b/xen/arch/arm/irq.c
> @@ -143,6 +143,16 @@ static inline struct domain *irq_get_domain(struct irq_desc *desc)
>      return irq_get_guest_info(desc)->d;
>  }
>
> +domid_t irq_get_domain_id(struct irq_desc *desc)
> +{
> +    /* If this domain isn't routed to a guest, return DOMID_XEN. */
> +    if ( !test_bit(_IRQ_GUEST, &desc->status) )
> +        return DOMID_XEN;
> +
> +    /* Otherise, get the guest domain's information. */

NIT: s/Otherise/Otherwise/

> +    return irq_get_domain(desc)->domain_id;
> +}
> +
>  void irq_set_affinity(struct irq_desc *desc, const cpumask_t *cpu_mask)
>  {
>      if ( desc != NULL )
> diff --git a/xen/include/asm-arm/irq.h b/xen/include/asm-arm/irq.h
> index 4849f16..d0fd6db 100644
> --- a/xen/include/asm-arm/irq.h
> +++ b/xen/include/asm-arm/irq.h
> @@ -44,6 +44,8 @@ int route_irq_to_guest(struct domain *d, unsigned int virq,
>                         unsigned int irq, const char *devname);
>  int release_guest_irq(struct domain *d, unsigned int irq);
>
> +domid_t irq_get_domain_id(struct irq_desc *desc);
> +
>  void arch_move_irqs(struct vcpu *v);
>
>  #define arch_evtchn_bind_pirq(d, pirq) ((void)((d) + (pirq)))
>

Cheers,

-- 
Julien Grall

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