From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Auger Subject: Re: [PATCH v7 5/8] genirq/irq: introduce msi_doorbell's structs and related callback Date: Wed, 20 Apr 2016 11:36:46 +0200 Message-ID: <57174DAE.4030101@linaro.org> References: <1461085990-2547-1-git-send-email-eric.auger@linaro.org> <1461085990-2547-6-git-send-email-eric.auger@linaro.org> <571748D8.3030402@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <571748D8.3030402-5wv7dgnIgG8@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Marc Zyngier , eric.auger-qxv4g6HH51o@public.gmane.org, robin.murphy-5wv7dgnIgG8@public.gmane.org, alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org, tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org, jason-NLaQJdtUoK4Be96aLqz0jA@public.gmane.org, christoffer.dall-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Cc: julien.grall-5wv7dgnIgG8@public.gmane.org, patches-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, p.fedin-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, pranav.sawargaonkar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org List-Id: iommu@lists.linux-foundation.org Hi Marc, On 04/20/2016 11:16 AM, Marc Zyngier wrote: > On 19/04/16 18:13, Eric Auger wrote: >> The purpose is to be able to retrieve the MSI doorbells of an irqchip. >> This is now needed since on some platforms those doorbells must be >> iommu mapped (in case the MSIs transit through an IOMMU that do not >> bypass those transactions). >> >> The assumption is there is a maximum of one doorbell region per cpu. >> The number of doorbells for the whole irqchip is stored in nb_doorbells. >> >> A doorbell region is characterized by its physical address base, size and >> IOMMU protection flag. >> >> irq_chip msi_doorbell_info callback enables to retrieve the doorbells of >> the irqchip. >> >> Signed-off-by: Eric Auger >> >> --- >> >> v7: creation >> --- >> include/linux/irq.h | 26 ++++++++++++++++++++++---- >> 1 file changed, 22 insertions(+), 4 deletions(-) >> >> diff --git a/include/linux/irq.h b/include/linux/irq.h >> index c4de623..fdad8c1 100644 >> --- a/include/linux/irq.h >> +++ b/include/linux/irq.h >> @@ -312,9 +312,25 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d) >> return d->hwirq; >> } >> >> -/** >> - * struct irq_chip - hardware interrupt chip descriptor >> - * >> +/* MSI doorbell region */ >> +struct irq_chip_msi_doorbell { >> + phys_addr_t base; >> + size_t size; >> + int prot; /* iommu protection flag */ > > I find this one a bit scary. "int" is a probably not the right type if > it is a set of flags (it should describe both the protection and the > memory attributes - in this case, probably something like Device + > Writeable). You should probably use the same type the IOMMU code uses > (and if it is actually an int, then I'll shut up...). Hum yes iommu also uses an int ;-) > >> +}; >> + >> +/* >> + * Describe all the MSI doorbell regions for an irqchip. >> + * A single doorbell region per cpu is assumed. >> + * In case a single doorbell is supported for the whole irqchip, >> + * the region is described in as cpu #0's one >> + */ >> +struct irq_chip_msi_doorbell_info { >> + struct irq_chip_msi_doorbell __percpu *percpu_doorbells; >> + int nb_doorbells; /* overall number of doorbells */ >> +}; > > How can size and prot be different from one CPU to another? It really > feels like they should be common. Can I suggest something like this? > > struct irq_chip_msi_doorbell_info { > phys_addr_t __percpu *doorbells; > size_t size; > u32 prot; > }; > > and get rid of struct irq_chip_msi_doorbell altogether? I'am definitively fine with your proposal. Thanks Eric > >> + >> +/** * struct irq_chip - hardware interrupt chip descriptor * >> * @name: name for /proc/interrupts >> * @irq_startup: start up the interrupt (defaults to ->enable if NULL) >> * @irq_shutdown: shut down the interrupt (defaults to ->disable if NULL) >> @@ -349,6 +365,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d) >> * @irq_get_irqchip_state: return the internal state of an interrupt >> * @irq_set_irqchip_state: set the internal state of a interrupt >> * @irq_set_vcpu_affinity: optional to target a vCPU in a virtual machine >> + * @msi_doorbell_info: return the MSI doorbell info >> * @ipi_send_single: send a single IPI to destination cpus >> * @ipi_send_mask: send an IPI to destination cpus in cpumask >> * @flags: chip specific flags >> @@ -394,7 +411,8 @@ struct irq_chip { >> int (*irq_set_irqchip_state)(struct irq_data *data, enum irqchip_irq_state which, bool state); >> >> int (*irq_set_vcpu_affinity)(struct irq_data *data, void *vcpu_info); >> - >> + const struct irq_chip_msi_doorbell_info *(*msi_doorbell_info)( >> + struct irq_data *data); >> void (*ipi_send_single)(struct irq_data *data, unsigned int cpu); >> void (*ipi_send_mask)(struct irq_data *data, const struct cpumask *dest); >> >> > > Thanks, > > M. >