Re: [PATCH v2 06/30] s390/airq: allow for airq structure that uses an input vector

[Pierre Morel <pmorel@linux.ibm.com>]

On 1/14/22 21:31, Matthew Rosato wrote:
> When doing device passthrough where interrupts are being forwarded
> from host to guest, we wish to use a pinned section of guest memory
> as the vector (the same memory used by the guest as the vector).
> 
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>


Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>


> ---
>   arch/s390/include/asm/airq.h     |  4 +++-
>   arch/s390/pci/pci_irq.c          |  8 ++++----
>   drivers/s390/cio/airq.c          | 10 +++++++---
>   drivers/s390/virtio/virtio_ccw.c |  2 +-
>   4 files changed, 15 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/s390/include/asm/airq.h b/arch/s390/include/asm/airq.h
> index 7918a7d09028..e82e5626e139 100644
> --- a/arch/s390/include/asm/airq.h
> +++ b/arch/s390/include/asm/airq.h
> @@ -47,8 +47,10 @@ struct airq_iv {
>   #define AIRQ_IV_PTR		4	/* Allocate the ptr array */
>   #define AIRQ_IV_DATA		8	/* Allocate the data array */
>   #define AIRQ_IV_CACHELINE	16	/* Cacheline alignment for the vector */
> +#define AIRQ_IV_GUESTVEC	32	/* Vector is a pinned guest page */
>   
> -struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags);
> +struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags,
> +			       unsigned long *vec);
>   void airq_iv_release(struct airq_iv *iv);
>   unsigned long airq_iv_alloc(struct airq_iv *iv, unsigned long num);
>   void airq_iv_free(struct airq_iv *iv, unsigned long bit, unsigned long num);
> diff --git a/arch/s390/pci/pci_irq.c b/arch/s390/pci/pci_irq.c
> index cc4c8d7c8f5c..0d0a02a9fbbf 100644
> --- a/arch/s390/pci/pci_irq.c
> +++ b/arch/s390/pci/pci_irq.c
> @@ -296,7 +296,7 @@ int arch_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
>   		zdev->aisb = bit;
>   
>   		/* Create adapter interrupt vector */
> -		zdev->aibv = airq_iv_create(msi_vecs, AIRQ_IV_DATA | AIRQ_IV_BITLOCK);
> +		zdev->aibv = airq_iv_create(msi_vecs, AIRQ_IV_DATA | AIRQ_IV_BITLOCK, NULL);
>   		if (!zdev->aibv)
>   			return -ENOMEM;
>   
> @@ -419,7 +419,7 @@ static int __init zpci_directed_irq_init(void)
>   	union zpci_sic_iib iib = {{0}};
>   	unsigned int cpu;
>   
> -	zpci_sbv = airq_iv_create(num_possible_cpus(), 0);
> +	zpci_sbv = airq_iv_create(num_possible_cpus(), 0, NULL);
>   	if (!zpci_sbv)
>   		return -ENOMEM;
>   
> @@ -441,7 +441,7 @@ static int __init zpci_directed_irq_init(void)
>   		zpci_ibv[cpu] = airq_iv_create(cache_line_size() * BITS_PER_BYTE,
>   					       AIRQ_IV_DATA |
>   					       AIRQ_IV_CACHELINE |
> -					       (!cpu ? AIRQ_IV_ALLOC : 0));
> +					       (!cpu ? AIRQ_IV_ALLOC : 0), NULL);
>   		if (!zpci_ibv[cpu])
>   			return -ENOMEM;
>   	}
> @@ -458,7 +458,7 @@ static int __init zpci_floating_irq_init(void)
>   	if (!zpci_ibv)
>   		return -ENOMEM;
>   
> -	zpci_sbv = airq_iv_create(ZPCI_NR_DEVICES, AIRQ_IV_ALLOC);
> +	zpci_sbv = airq_iv_create(ZPCI_NR_DEVICES, AIRQ_IV_ALLOC, NULL);
>   	if (!zpci_sbv)
>   		goto out_free;
>   
> diff --git a/drivers/s390/cio/airq.c b/drivers/s390/cio/airq.c
> index 2f2226786319..375a58b1c838 100644
> --- a/drivers/s390/cio/airq.c
> +++ b/drivers/s390/cio/airq.c
> @@ -122,10 +122,12 @@ static inline unsigned long iv_size(unsigned long bits)
>    * airq_iv_create - create an interrupt vector
>    * @bits: number of bits in the interrupt vector
>    * @flags: allocation flags
> + * @vec: pointer to pinned guest memory if AIRQ_IV_GUESTVEC
>    *
>    * Returns a pointer to an interrupt vector structure
>    */
> -struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags)
> +struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags,
> +			       unsigned long *vec)
>   {
>   	struct airq_iv *iv;
>   	unsigned long size;
> @@ -146,6 +148,8 @@ struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags)
>   					     &iv->vector_dma);
>   		if (!iv->vector)
>   			goto out_free;
> +	} else if (flags & AIRQ_IV_GUESTVEC) {
> +		iv->vector = vec;
>   	} else {
>   		iv->vector = cio_dma_zalloc(size);
>   		if (!iv->vector)
> @@ -185,7 +189,7 @@ struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags)
>   	kfree(iv->avail);
>   	if (iv->flags & AIRQ_IV_CACHELINE && iv->vector)
>   		dma_pool_free(airq_iv_cache, iv->vector, iv->vector_dma);
> -	else
> +	else if (!(iv->flags & AIRQ_IV_GUESTVEC))
>   		cio_dma_free(iv->vector, size);
>   	kfree(iv);
>   out:
> @@ -204,7 +208,7 @@ void airq_iv_release(struct airq_iv *iv)
>   	kfree(iv->bitlock);
>   	if (iv->flags & AIRQ_IV_CACHELINE)
>   		dma_pool_free(airq_iv_cache, iv->vector, iv->vector_dma);
> -	else
> +	else if (!(iv->flags & AIRQ_IV_GUESTVEC))
>   		cio_dma_free(iv->vector, iv_size(iv->bits));
>   	kfree(iv->avail);
>   	kfree(iv);
> diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
> index 52c376d15978..410498d693f8 100644
> --- a/drivers/s390/virtio/virtio_ccw.c
> +++ b/drivers/s390/virtio/virtio_ccw.c
> @@ -241,7 +241,7 @@ static struct airq_info *new_airq_info(int index)
>   		return NULL;
>   	rwlock_init(&info->lock);
>   	info->aiv = airq_iv_create(VIRTIO_IV_BITS, AIRQ_IV_ALLOC | AIRQ_IV_PTR
> -				   | AIRQ_IV_CACHELINE);
> +				   | AIRQ_IV_CACHELINE, NULL);
>   	if (!info->aiv) {
>   		kfree(info);
>   		return NULL;
> 

-- 
Pierre Morel
IBM Lab Boeblingen