[PATCH v5 4/8] s390/airq: use DMA memory for adapter interrupts

Halil Pasic
2019-06-12T11:13:12Z

Protected virtualization guests have to use shared pages for airq
notifier bit vectors, because hypervisor needs to write these bits.

Let us make sure we allocate DMA memory for the notifier bit vectors by
replacing the kmem_cache with a dma_cache and kalloc() with
cio_dma_zalloc().

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Sebastian Ott <sebott@linux.ibm.com>
---
arch/s390/include/asm/airq.h | 2 ++
drivers/s390/cio/airq.c | 37 ++++++++++++++++++++++--------------
drivers/s390/cio/cio.h | 2 ++
drivers/s390/cio/css.c | 1 +
4 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/arch/s390/include/asm/airq.h b/arch/s390/include/asm/airq.h
index c10d2ee2dfda..01936fdfaddb 100644
--- a/arch/s390/include/asm/airq.h
+++ b/arch/s390/include/asm/airq.h
@@ -11,6 +11,7 @@
#define _ASM_S390_AIRQ_H

#include <linux/bit_spinlock.h>
+#include <linux/dma-mapping.h>

struct airq_struct {
struct hlist_node list; /* Handler queueing. */
@@ -29,6 +30,7 @@ void unregister_adapter_interrupt(struct airq_struct *airq);
/* Adapter interrupt bit vector */
struct airq_iv {
unsigned long *vector; /* Adapter interrupt bit vector */
+ dma_addr_t vector_dma; /* Adapter interrupt bit vector dma */
unsigned long *avail; /* Allocation bit mask for the bit vector */
unsigned long *bitlock; /* Lock bit mask for the bit vector */
unsigned long *ptr; /* Pointer associated with each bit */
diff --git a/drivers/s390/cio/airq.c b/drivers/s390/cio/airq.c
index 4534afc63591..427b2e24a8ce 100644
--- a/drivers/s390/cio/airq.c
+++ b/drivers/s390/cio/airq.c
@@ -16,9 +16,11 @@
#include <linux/mutex.h>
#include <linux/rculist.h>
#include <linux/slab.h>
+#include <linux/dmapool.h>

#include <asm/airq.h>
#include <asm/isc.h>
+#include <asm/cio.h>

#include "cio.h"
#include "cio_debug.h"
@@ -27,7 +29,7 @@
static DEFINE_SPINLOCK(airq_lists_lock);
static struct hlist_head airq_lists[MAX_ISC+1];

-static struct kmem_cache *airq_iv_cache;
+static struct dma_pool *airq_iv_cache;

/**
* register_adapter_interrupt() - register adapter interrupt handler
@@ -115,6 +117,11 @@ void __init init_airq_interrupts(void)
setup_irq(THIN_INTERRUPT, &airq_interrupt);
}

+static inline unsigned long iv_size(unsigned long bits)
+{
+ return BITS_TO_LONGS(bits) * sizeof(unsigned long);
+}
+
/**
* airq_iv_create - create an interrupt vector
* @bits: number of bits in the interrupt vector
@@ -132,17 +139,19 @@ struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags)
goto out;
iv->bits = bits;
iv->flags = flags;
- size = BITS_TO_LONGS(bits) * sizeof(unsigned long);
+ size = iv_size(bits);

if (flags & AIRQ_IV_CACHELINE) {
- if ((cache_line_size() * BITS_PER_BYTE) < bits)
+ if ((cache_line_size() * BITS_PER_BYTE) < bits
+ || !airq_iv_cache)
goto out_free;

- iv->vector = kmem_cache_zalloc(airq_iv_cache, GFP_KERNEL);
+ iv->vector = dma_pool_zalloc(airq_iv_cache, GFP_KERNEL,
+ &iv->vector_dma);
if (!iv->vector)
goto out_free;
} else {
- iv->vector = kzalloc(size, GFP_KERNEL);
+ iv->vector = cio_dma_zalloc(size);
if (!iv->vector)
goto out_free;
}
@@ -178,10 +187,10 @@ struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags)
kfree(iv->ptr);
kfree(iv->bitlock);
kfree(iv->avail);
- if (iv->flags & AIRQ_IV_CACHELINE)
- kmem_cache_free(airq_iv_cache, iv->vector);
+ if (iv->flags & AIRQ_IV_CACHELINE && iv->vector)
+ dma_pool_free(airq_iv_cache, iv->vector, iv->vector_dma);
else
- kfree(iv->vector);
+ cio_dma_free(iv->vector, size);
kfree(iv);
out:
return NULL;
@@ -198,9 +207,9 @@ void airq_iv_release(struct airq_iv *iv)
kfree(iv->ptr);
kfree(iv->bitlock);
if (iv->flags & AIRQ_IV_CACHELINE)
- kmem_cache_free(airq_iv_cache, iv->vector);
+ dma_pool_free(airq_iv_cache, iv->vector, iv->vector_dma);
else
- kfree(iv->vector);
+ cio_dma_free(iv->vector, iv_size(iv->bits));
kfree(iv->avail);
kfree(iv);
}
@@ -295,12 +304,12 @@ unsigned long airq_iv_scan(struct airq_iv *iv, unsigned long start,
}
EXPORT_SYMBOL(airq_iv_scan);

-static int __init airq_init(void)
+int __init airq_init(void)
{
- airq_iv_cache = kmem_cache_create("airq_iv_cache", cache_line_size(),
- cache_line_size(), 0, NULL);
+ airq_iv_cache = dma_pool_create("airq_iv_cache", cio_get_dma_css_dev(),
+ cache_line_size(),
+ cache_line_size(), PAGE_SIZE);
if (!airq_iv_cache)
return -ENOMEM;
return 0;
}
-subsys_initcall(airq_init);
diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h
index 06a91743335a..4d6c7d16416e 100644
--- a/drivers/s390/cio/cio.h
+++ b/drivers/s390/cio/cio.h
@@ -135,6 +135,8 @@ extern int cio_commit_config(struct subchannel *sch);
int cio_tm_start_key(struct subchannel *sch, struct tcw *tcw, u8 lpm, u8 key);
int cio_tm_intrg(struct subchannel *sch);

+extern int __init airq_init(void);
+
/* Use with care. */
#ifdef CONFIG_CCW_CONSOLE
extern struct subchannel *cio_probe_console(void);
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index e0f19f1e82a0..1b867c941b86 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -1184,6 +1184,7 @@ static int __init css_bus_init(void)
ret = cio_dma_pool_init();
if (ret)
goto out_unregister_pmn;
+ airq_init();
css_init_done = 1;

/* Enable default isc for I/O subchannels. */
--
2.17.1