Re: [PATCH kernel v4 4/6] iommu: Set PCI_BUS_FLAGS_MSI_REMAP on iommu driver initialization

[Jike Song <jike.song@intel.com>]

On 06/30/2017 01:24 PM, Alexey Kardashevskiy wrote:
> From: Yongji Xie <elohimes@gmail.com>
> 
> Some iommu drivers would be initialized after PCI device
> enumeration. So PCI_BUS_FLAGS_MSI_REMAP would not be set
> when probing PCI devices although IOMMU enables capability
> of IRQ remapping. This patch tests this capability and
> set the flag when iommu driver is initialized.
> 
> Signed-off-by: Yongji Xie <xyjxie@linux.vnet.ibm.com>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
>  drivers/iommu/iommu.c | 8 ++++++++
>  drivers/pci/probe.c   | 1 +
>  2 files changed, 9 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index cf7ca7e70777..0b5881ddca09 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1063,6 +1063,14 @@ static int add_iommu_group(struct device *dev, void *data)
>  	const struct iommu_ops *ops = cb->ops;
>  	int ret;
>  
> +	/*
> +	 * Set PCI_BUS_FLAGS_MSI_REMAP for all PCI buses when IOMMU
> +	 * have capability of IRQ remapping.
> +	 */
> +	if (dev_is_pci(dev) && ops->capable &&
> +			ops->capable(IOMMU_CAP_INTR_REMAP))
> +		to_pci_dev(dev)->bus->bus_flags |= PCI_BUS_FLAGS_MSI_REMAP;

[+Kevin]


Hi Alexey,

Just a reminder, you might want to check the proposed patch to intel-iommu
by Alex, at:

	https://patchwork.kernel.org/patch/9092511/

Without that being the prerequisite, this patch will probably introduce
security issues on x86.

--
Thanks,
Jike

> +
>  	if (!ops->add_device)
>  		return 0;
>  
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index f2393b7d7ebf..14aac9df3d17 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -17,6 +17,7 @@
>  #include <linux/acpi.h>
>  #include <linux/irqdomain.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/iommu.h>
>  #include "pci.h"
>  
>  #define CARDBUS_LATENCY_TIMER	176	/* secondary latency timer */
>