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

Pierre Morel <pmorel@xxxxxxxxxxxxx> · Tue, 18 Jan 2022 10:50:07 +0100

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@xxxxxxxxxxxxx>


Reviewed-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>


---
  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






