[PATCH v3 06/30] s390/airq: allow for airq structure that uses an input vector

Matthew Rosato
2022-02-04T21:16:04Z

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). To accomplish
this, add a new parameter for airq_iv_create which allows passing an
existing vector to be used instead of allocating a new one. The caller
is responsible for ensuring the vector is pinned in memory as well as for
unpinning the memory when the vector is no longer needed.

A subsequent patch will use this new parameter for zPCI interpretation.

Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@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;
--
2.27.0