linux-kernel - RE: [PATCH v6 17/18] vfio/type1: Check MSI remapping at irq domain level

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Date:   Fri, 6 Jan 2017 08:50:20 +0000
From:   Bharat Bhushan <bharat.bhushan@....com>
To:     Eric Auger <eric.auger@...hat.com>,
        "eric.auger.pro@...il.com" <eric.auger.pro@...il.com>,
        "christoffer.dall@...aro.org" <christoffer.dall@...aro.org>,
        "marc.zyngier@....com" <marc.zyngier@....com>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "will.deacon@....com" <will.deacon@....com>,
        "joro@...tes.org" <joro@...tes.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "jason@...edaemon.net" <jason@...edaemon.net>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "drjones@...hat.com" <drjones@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "pranav.sawargaonkar@...il.com" <pranav.sawargaonkar@...il.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "punit.agrawal@....com" <punit.agrawal@....com>,
        Diana Madalina Craciun <diana.craciun@....com>,
        "gpkulkarni@...il.com" <gpkulkarni@...il.com>,
        "shankerd@...eaurora.org" <shankerd@...eaurora.org>,
        "geethasowjanya.akula@...il.com" <geethasowjanya.akula@...il.com>
Subject: RE: [PATCH v6 17/18] vfio/type1: Check MSI remapping at irq domain
 level

Hi Eric,

> -----Original Message-----
> From: Eric Auger [mailto:eric.auger@...hat.com]
> Sent: Friday, January 06, 2017 12:35 AM
> To: eric.auger@...hat.com; eric.auger.pro@...il.com;
> christoffer.dall@...aro.org; marc.zyngier@....com;
> robin.murphy@....com; alex.williamson@...hat.com;
> will.deacon@....com; joro@...tes.org; tglx@...utronix.de;
> jason@...edaemon.net; linux-arm-kernel@...ts.infradead.org
> Cc: kvm@...r.kernel.org; drjones@...hat.com; linux-
> kernel@...r.kernel.org; pranav.sawargaonkar@...il.com;
> iommu@...ts.linux-foundation.org; punit.agrawal@....com; Diana Madalina
> Craciun <diana.craciun@....com>; gpkulkarni@...il.com;
> shankerd@...eaurora.org; Bharat Bhushan <bharat.bhushan@....com>;
> geethasowjanya.akula@...il.com
> Subject: [PATCH v6 17/18] vfio/type1: Check MSI remapping at irq domain
> level
> 
> In case the IOMMU translates MSI transactions (typical case on ARM), we
> check MSI remapping capability at IRQ domain level. Otherwise it is checked
> at IOMMU level.
> 
> At this stage the arm-smmu-(v3) still advertise the
> IOMMU_CAP_INTR_REMAP capability at IOMMU level. This will be removed
> in subsequent patches.
> 
> Signed-off-by: Eric Auger <eric.auger@...hat.com>
> 
> ---
> 
> v6: rewrite test
> ---
>  drivers/vfio/vfio_iommu_type1.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c
> b/drivers/vfio/vfio_iommu_type1.c index b473ef80..fa0b5c4 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -40,6 +40,7 @@
>  #include <linux/mdev.h>
>  #include <linux/notifier.h>
>  #include <linux/dma-iommu.h>
> +#include <linux/irqdomain.h>
> 
>  #define DRIVER_VERSION  "0.2"
>  #define DRIVER_AUTHOR   "Alex Williamson
> <alex.williamson@...hat.com>"
> @@ -1208,7 +1209,7 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
>  	struct vfio_domain *domain, *d;
>  	struct bus_type *bus = NULL, *mdev_bus;
>  	int ret;
> -	bool resv_msi;
> +	bool resv_msi, msi_remap;
>  	phys_addr_t resv_msi_base;
> 
>  	mutex_lock(&iommu->lock);
> @@ -1284,8 +1285,10 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
>  	INIT_LIST_HEAD(&domain->group_list);
>  	list_add(&group->next, &domain->group_list);
> 
> -	if (!allow_unsafe_interrupts &&
> -	    !iommu_capable(bus, IOMMU_CAP_INTR_REMAP)) {
> +	msi_remap = resv_msi ? irq_domain_check_msi_remap() :

There can be multiple interrupt-controller, at-least theoretically it is possible and not sure practically it exists and supported, where not all may support IRQ_REMAP. If that is the case be then should we check for IRQ-REMAP for that device-bus irq-domain?

Thanks
-Bharat

> +				iommu_capable(bus,
> IOMMU_CAP_INTR_REMAP);
> +
> +	if (!allow_unsafe_interrupts && !msi_remap) {
>  		pr_warn("%s: No interrupt remapping support.  Use the
> module param \"allow_unsafe_interrupts\" to enable VFIO IOMMU support
> on this platform\n",
>  		       __func__);
>  		ret = -EPERM;
> --
> 1.9.1