Re: [PATCH v6 12/13] xen/arm: Suspend/resume IOMMU on Xen suspend/resume

[Mykola Kvach <xakep.amatop@xxxxxxxxx>]

Hi Oleksandr,

On Tue, Sep 2, 2025 at 8:25 PM Oleksandr Tyshchenko <olekstysh@xxxxxxxxx> wrote:
>
>
>
> On 02.09.25 01:10, Mykola Kvach wrote:
>
> Hello Mykola
>
> > From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> >
> > This is done using generic iommu_suspend/resume functions that cause
> > IOMMU driver specific suspend/resume handlers to be called for enabled
> > IOMMU (if one has suspend/resume driver handlers implemented).
> >
> > Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> > Signed-off-by: Mykola Kvach <mykola_kvach@xxxxxxxx>
> > ---
> > Changes in V6:
> > - Drop iommu_enabled check from host system suspend.
>
> I do not have any comments for the updated version, thanks.

Thank you for your time and the review!

>
>
> > ---
> >   xen/arch/arm/suspend.c                | 11 +++++++++++
> >   xen/drivers/passthrough/arm/smmu-v3.c | 10 ++++++++++
> >   xen/drivers/passthrough/arm/smmu.c    | 10 ++++++++++
> >   3 files changed, 31 insertions(+)
> >
> > diff --git a/xen/arch/arm/suspend.c b/xen/arch/arm/suspend.c
> > index 35b20581f1..f3a3b831c5 100644
> > --- a/xen/arch/arm/suspend.c
> > +++ b/xen/arch/arm/suspend.c
> > @@ -5,6 +5,7 @@
> >
> >   #include <xen/console.h>
> >   #include <xen/cpu.h>
> > +#include <xen/iommu.h>
> >   #include <xen/llc-coloring.h>
> >   #include <xen/sched.h>
> >   #include <xen/tasklet.h>
> > @@ -62,6 +63,13 @@ static void cf_check system_suspend(void *data)
> >
> >       time_suspend();
> >
> > +    status = iommu_suspend();
> > +    if ( status )
> > +    {
> > +        system_state = SYS_STATE_resume;
> > +        goto resume_time;
> > +    }
> > +
> >       console_start_sync();
> >       status = console_suspend();
> >       if ( status )
> > @@ -118,6 +126,9 @@ static void cf_check system_suspend(void *data)
> >       console_resume();
> >       console_end_sync();
> >
> > +    iommu_resume();
> > +
> > + resume_time:
> >       time_resume();
> >
> >    resume_nonboot_cpus:
> > diff --git a/xen/drivers/passthrough/arm/smmu-v3.c 
> > b/xen/drivers/passthrough/arm/smmu-v3.c
> > index 81071f4018..f887faf7dc 100644
> > --- a/xen/drivers/passthrough/arm/smmu-v3.c
> > +++ b/xen/drivers/passthrough/arm/smmu-v3.c
> > @@ -2854,6 +2854,13 @@ static void 
> > arm_smmu_iommu_xen_domain_teardown(struct domain *d)
> >       xfree(xen_domain);
> >   }
> >
> > +#ifdef CONFIG_SYSTEM_SUSPEND
> > +static int arm_smmu_suspend(void)
> > +{
> > +     return -ENOSYS;
> > +}
> > +#endif
> > +
> >   static const struct iommu_ops arm_smmu_iommu_ops = {
> >       .page_sizes             = PAGE_SIZE_4K,
> >       .init                   = arm_smmu_iommu_xen_domain_init,
> > @@ -2866,6 +2873,9 @@ static const struct iommu_ops arm_smmu_iommu_ops = {
> >       .unmap_page             = arm_iommu_unmap_page,
> >       .dt_xlate               = arm_smmu_dt_xlate,
> >       .add_device             = arm_smmu_add_device,
> > +#ifdef CONFIG_SYSTEM_SUSPEND
> > +     .suspend                = arm_smmu_suspend,
> > +#endif
> >   };
> >
> >   static __init int arm_smmu_dt_init(struct dt_device_node *dev,
> > diff --git a/xen/drivers/passthrough/arm/smmu.c 
> > b/xen/drivers/passthrough/arm/smmu.c
> > index 22d306d0cb..45f29ef8ec 100644
> > --- a/xen/drivers/passthrough/arm/smmu.c
> > +++ b/xen/drivers/passthrough/arm/smmu.c
> > @@ -2947,6 +2947,13 @@ static void arm_smmu_iommu_domain_teardown(struct 
> > domain *d)
> >       xfree(xen_domain);
> >   }
> >
> > +#ifdef CONFIG_SYSTEM_SUSPEND
> > +static int arm_smmu_suspend(void)
> > +{
> > +     return -ENOSYS;
> > +}
> > +#endif
> > +
> >   static const struct iommu_ops arm_smmu_iommu_ops = {
> >       .page_sizes = PAGE_SIZE_4K,
> >       .init = arm_smmu_iommu_domain_init,
> > @@ -2960,6 +2967,9 @@ static const struct iommu_ops arm_smmu_iommu_ops = {
> >       .map_page = arm_iommu_map_page,
> >       .unmap_page = arm_iommu_unmap_page,
> >       .dt_xlate = arm_smmu_dt_xlate_generic,
> > +#ifdef CONFIG_SYSTEM_SUSPEND
> > +    .suspend = arm_smmu_suspend,
> > +#endif
> >   };
> >
> >   static struct arm_smmu_device *find_smmu(const struct device *dev)
>

Best regards,
Mykola