| Message ID | 1483969570-3154-16-git-send-email-eric.auger@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 09/01/17 13:46, Eric Auger wrote: > This new function checks whether all MSI irq domains > implement IRQ remapping. This is useful to understand > whether VFIO passthrough is safe with respect to interrupts. > > On ARM typically an MSI controller can sit downstream > to the IOMMU without preventing VFIO passthrough. > As such any assigned device can write into the MSI doorbell. > In case the MSI controller implements IRQ remapping, assigned > devices will not be able to trigger interrupts towards the > host. On the contrary, the assignment must be emphasized as > unsafe with respect to interrupts. > > Signed-off-by: Eric Auger <eric.auger@redhat.com> > > --- > v5 -> v6: > - use irq_domain_hierarchical_is_msi_remap() > - comment rewording > > v4 -> v5: > - Handle DOMAIN_BUS_FSL_MC_MSI domains > - Check parents > --- > include/linux/irqdomain.h | 1 + > kernel/irq/irqdomain.c | 23 +++++++++++++++++++++++ > 2 files changed, 24 insertions(+) > > diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h > index bc2f571..188eced 100644 > --- a/include/linux/irqdomain.h > +++ b/include/linux/irqdomain.h > @@ -222,6 +222,7 @@ struct irq_domain *irq_domain_add_legacy(struct device_node *of_node, > void *host_data); > extern struct irq_domain *irq_find_matching_fwspec(struct irq_fwspec *fwspec, > enum irq_domain_bus_token bus_token); > +extern bool irq_domain_check_msi_remap(void); > extern void irq_set_default_host(struct irq_domain *host); > extern int irq_domain_alloc_descs(int virq, unsigned int nr_irqs, > irq_hw_number_t hwirq, int node, > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c > index 101ee8f..fff30cb 100644 > --- a/kernel/irq/irqdomain.c > +++ b/kernel/irq/irqdomain.c > @@ -278,6 +278,29 @@ struct irq_domain *irq_find_matching_fwspec(struct irq_fwspec *fwspec, > EXPORT_SYMBOL_GPL(irq_find_matching_fwspec); > > /** > + * irq_domain_check_msi_remap - Check whether all MSI > + * irq domains implement IRQ remapping > + */ > +bool irq_domain_check_msi_remap(void) > +{ > + struct irq_domain *h; > + bool ret = true; > + > + mutex_lock(&irq_domain_mutex); > + list_for_each_entry(h, &irq_domain_list, link) { > + if (irq_domain_is_msi(h) && > + !irq_domain_hierarchical_is_msi_remap(h)) { > + ret = false; > + goto out; Let's avoid gotos if we can. a break statement will have the same effect here, and we can drop the label. > + } > + } > +out: > + mutex_unlock(&irq_domain_mutex); > + return ret; > +} > +EXPORT_SYMBOL_GPL(irq_domain_check_msi_remap); > + > +/** > * irq_set_default_host() - Set a "default" irq domain > * @domain: default domain pointer > * > Thanks, M.
diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h index bc2f571..188eced 100644 --- a/include/linux/irqdomain.h +++ b/include/linux/irqdomain.h @@ -222,6 +222,7 @@ struct irq_domain *irq_domain_add_legacy(struct device_node *of_node, void *host_data); extern struct irq_domain *irq_find_matching_fwspec(struct irq_fwspec *fwspec, enum irq_domain_bus_token bus_token); +extern bool irq_domain_check_msi_remap(void); extern void irq_set_default_host(struct irq_domain *host); extern int irq_domain_alloc_descs(int virq, unsigned int nr_irqs, irq_hw_number_t hwirq, int node, diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c index 101ee8f..fff30cb 100644 --- a/kernel/irq/irqdomain.c +++ b/kernel/irq/irqdomain.c @@ -278,6 +278,29 @@ struct irq_domain *irq_find_matching_fwspec(struct irq_fwspec *fwspec, EXPORT_SYMBOL_GPL(irq_find_matching_fwspec); /** + * irq_domain_check_msi_remap - Check whether all MSI + * irq domains implement IRQ remapping + */ +bool irq_domain_check_msi_remap(void) +{ + struct irq_domain *h; + bool ret = true; + + mutex_lock(&irq_domain_mutex); + list_for_each_entry(h, &irq_domain_list, link) { + if (irq_domain_is_msi(h) && + !irq_domain_hierarchical_is_msi_remap(h)) { + ret = false; + goto out; + } + } +out: + mutex_unlock(&irq_domain_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(irq_domain_check_msi_remap); + +/** * irq_set_default_host() - Set a "default" irq domain * @domain: default domain pointer *
This new function checks whether all MSI irq domains implement IRQ remapping. This is useful to understand whether VFIO passthrough is safe with respect to interrupts. On ARM typically an MSI controller can sit downstream to the IOMMU without preventing VFIO passthrough. As such any assigned device can write into the MSI doorbell. In case the MSI controller implements IRQ remapping, assigned devices will not be able to trigger interrupts towards the host. On the contrary, the assignment must be emphasized as unsafe with respect to interrupts. Signed-off-by: Eric Auger <eric.auger@redhat.com> --- v5 -> v6: - use irq_domain_hierarchical_is_msi_remap() - comment rewording v4 -> v5: - Handle DOMAIN_BUS_FSL_MC_MSI domains - Check parents --- include/linux/irqdomain.h | 1 + kernel/irq/irqdomain.c | 23 +++++++++++++++++++++++ 2 files changed, 24 insertions(+)