linux-kernel - Re: [PATCH v8 24/29] vfio: VFIO_IOMMU_BIND/UNBIND

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Message-ID: <0859eb67-4f77-1adb-7b34-2969060211c5@redhat.com>
Date:   Fri, 7 Jun 2019 10:30:00 +0200
From:   Auger Eric <eric.auger@...hat.com>
To:     Alex Williamson <alex.williamson@...hat.com>
Cc:     eric.auger.pro@...il.com, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        kvmarm@...ts.cs.columbia.edu, joro@...tes.org,
        jacob.jun.pan@...ux.intel.com, yi.l.liu@...el.com,
        jean-philippe.brucker@....com, will.deacon@....com,
        robin.murphy@....com, kevin.tian@...el.com, ashok.raj@...el.com,
        marc.zyngier@....com, peter.maydell@...aro.org,
        vincent.stehle@....com
Subject: Re: [PATCH v8 24/29] vfio: VFIO_IOMMU_BIND/UNBIND_MSI

Hi Alex,

On 6/4/19 12:32 AM, Alex Williamson wrote:
> On Sun, 26 May 2019 18:09:59 +0200
> Eric Auger <eric.auger@...hat.com> wrote:
> 
>> This patch adds the VFIO_IOMMU_BIND/UNBIND_MSI ioctl which aim
>> to pass/withdraw the guest MSI binding to/from the host.
>>
>> Signed-off-by: Eric Auger <eric.auger@...hat.com>
>>
>> ---
>> v6 -> v7:
>> - removed the dev arg
>>
>> v3 -> v4:
>> - add UNBIND
>> - unwind on BIND error
>>
>> v2 -> v3:
>> - adapt to new proto of bind_guest_msi
>> - directly use vfio_iommu_for_each_dev
>>
>> v1 -> v2:
>> - s/vfio_iommu_type1_guest_msi_binding/vfio_iommu_type1_bind_guest_msi
>> ---
>>  drivers/vfio/vfio_iommu_type1.c | 64 +++++++++++++++++++++++++++++++++
>>  include/uapi/linux/vfio.h       | 29 +++++++++++++++
>>  2 files changed, 93 insertions(+)
>>
>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
>> index 6fda4fbc9bfa..18142cb078a3 100644
>> --- a/drivers/vfio/vfio_iommu_type1.c
>> +++ b/drivers/vfio/vfio_iommu_type1.c
>> @@ -1832,6 +1832,42 @@ static int vfio_cache_inv_fn(struct device *dev, void *data)
>>  	return iommu_cache_invalidate(dc->domain, dev, &ustruct->info);
>>  }
>>  
>> +static int
>> +vfio_bind_msi(struct vfio_iommu *iommu,
>> +	      dma_addr_t giova, phys_addr_t gpa, size_t size)
>> +{
>> +	struct vfio_domain *d;
>> +	int ret = 0;
>> +
>> +	mutex_lock(&iommu->lock);
>> +
>> +	list_for_each_entry(d, &iommu->domain_list, next) {
>> +		ret = iommu_bind_guest_msi(d->domain, giova, gpa, size);
>> +		if (ret)
>> +			goto unwind;
>> +	}
>> +	goto unlock;
>> +unwind:
>> +	list_for_each_entry_continue_reverse(d, &iommu->domain_list, next) {
>> +		iommu_unbind_guest_msi(d->domain, giova);
>> +	}
>> +unlock:
>> +	mutex_unlock(&iommu->lock);
>> +	return ret;
>> +}
>> +
>> +static void
>> +vfio_unbind_msi(struct vfio_iommu *iommu, dma_addr_t giova)
>> +{
>> +	struct vfio_domain *d;
>> +
>> +	mutex_lock(&iommu->lock);
>> +	list_for_each_entry(d, &iommu->domain_list, next) {
>> +		iommu_unbind_guest_msi(d->domain, giova);
>> +	}
>> +	mutex_unlock(&iommu->lock);
>> +}
>> +
>>  static long vfio_iommu_type1_ioctl(void *iommu_data,
>>  				   unsigned int cmd, unsigned long arg)
>>  {
>> @@ -1936,6 +1972,34 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
>>  					    &ustruct);
>>  		mutex_unlock(&iommu->lock);
>>  		return ret;
>> +	} else if (cmd == VFIO_IOMMU_BIND_MSI) {
>> +		struct vfio_iommu_type1_bind_msi ustruct;
>> +
>> +		minsz = offsetofend(struct vfio_iommu_type1_bind_msi,
>> +				    size);
>> +
>> +		if (copy_from_user(&ustruct, (void __user *)arg, minsz))
>> +			return -EFAULT;
>> +
>> +		if (ustruct.argsz < minsz || ustruct.flags)
>> +			return -EINVAL;
>> +
>> +		return vfio_bind_msi(iommu, ustruct.iova, ustruct.gpa,
>> +				     ustruct.size);
>> +	} else if (cmd == VFIO_IOMMU_UNBIND_MSI) {
>> +		struct vfio_iommu_type1_unbind_msi ustruct;
>> +
>> +		minsz = offsetofend(struct vfio_iommu_type1_unbind_msi,
>> +				    iova);
>> +
>> +		if (copy_from_user(&ustruct, (void __user *)arg, minsz))
>> +			return -EFAULT;
>> +
>> +		if (ustruct.argsz < minsz || ustruct.flags)
>> +			return -EINVAL;
>> +
>> +		vfio_unbind_msi(iommu, ustruct.iova);
>> +		return 0;
>>  	}
>>  
>>  	return -ENOTTY;
>> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
>> index 055aa9b9745a..2774a1ab37ae 100644
>> --- a/include/uapi/linux/vfio.h
>> +++ b/include/uapi/linux/vfio.h
>> @@ -798,6 +798,35 @@ struct vfio_iommu_type1_cache_invalidate {
>>  };
>>  #define VFIO_IOMMU_CACHE_INVALIDATE      _IO(VFIO_TYPE, VFIO_BASE + 24)
>>  
>> +/**
>> + * VFIO_IOMMU_BIND_MSI - _IOWR(VFIO_TYPE, VFIO_BASE + 25,
>> + *			struct vfio_iommu_type1_bind_msi)
>> + *
>> + * Pass a stage 1 MSI doorbell mapping to the host so that this
>> + * latter can build a nested stage2 mapping
>> + */
>> +struct vfio_iommu_type1_bind_msi {
>> +	__u32   argsz;
>> +	__u32   flags;
>> +	__u64	iova;
>> +	__u64	gpa;
>> +	__u64	size;
>> +};
>> +#define VFIO_IOMMU_BIND_MSI      _IO(VFIO_TYPE, VFIO_BASE + 25)
>> +
>> +/**
>> + * VFIO_IOMMU_UNBIND_MSI - _IOWR(VFIO_TYPE, VFIO_BASE + 26,
>> + *			struct vfio_iommu_type1_unbind_msi)
>> + *
>> + * Unregister an MSI mapping
>> + */
>> +struct vfio_iommu_type1_unbind_msi {
>> +	__u32   argsz;
>> +	__u32   flags;
>> +	__u64	iova;
>> +};
>> +#define VFIO_IOMMU_UNBIND_MSI      _IO(VFIO_TYPE, VFIO_BASE + 26)
>> +
>>  /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
>>  
>>  /*
> 
> And another pair of ioctls.  Maybe think about how we can reduce the
> ioctl bloat of this series.  I don't want to impose an awkward
> interface for the sake of fewer ioctls, but I also don't want us
> casually burning through ioctls.
OK, understood.

Thanks

Eric
>