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vfio-ccw: Move guest_cp storage into common struct 

Rather than allocating/freeing a piece of memory every time
we try to figure out how long a CCW chain is, let's use a piece
of memory allocated for each device.

The io_mutex added with commit 4f76617378 ("vfio-ccw: protect
the I/O region") is held for the duration of the VFIO_CCW_EVENT_IO_REQ
event that accesses/uses this space, so there should be no race
concerns with another CPU attempting an (unexpected) SSCH for the
same device.

Suggested-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Message-Id: <20190618202352.39702-2-farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
This commit is contained in:
Eric Farman 2019-06-18 22:23:48 +02:00 committed by Cornelia Huck
parent 01aa26c672
commit 1d897e478d
3 changed files with 18 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/s390/cio/vfio_ccw_cp.c
View File

@ -16,12 +16,6 @@
#include "vfio_ccw_cp.h"
/*
* Max length for ccw chain.
* XXX: Limit to 256, need to check more?
*/
#define CCWCHAIN_LEN_MAX 256
struct pfn_array {
/* Starting guest physical I/O address. */
unsigned long pa_iova;
@ -386,7 +380,7 @@ static void ccwchain_cda_free(struct ccwchain *chain, int idx)
*/
static int ccwchain_calc_length(u64 iova, struct channel_program *cp)
{
struct ccw1 *ccw, *p;
struct ccw1 *ccw = cp->guest_cp;
int cnt;
/*
@ -394,15 +388,9 @@ static int ccwchain_calc_length(u64 iova, struct channel_program *cp)
* Currently the chain length is limited to CCWCHAIN_LEN_MAX (256).
* So copying 2K is enough (safe).
*/
p = ccw = kcalloc(CCWCHAIN_LEN_MAX, sizeof(*ccw), GFP_KERNEL);
if (!ccw)
return -ENOMEM;
cnt = copy_ccw_from_iova(cp, ccw, iova, CCWCHAIN_LEN_MAX);
if (cnt) {
kfree(ccw);
if (cnt)
return cnt;
}
cnt = 0;
do {
@ -413,10 +401,8 @@ static int ccwchain_calc_length(u64 iova, struct channel_program *cp)
* orb specified one of the unsupported formats, we defer
* checking for IDAWs in unsupported formats to here.
*/
if ((!cp->orb.cmd.c64 || cp->orb.cmd.i2k) && ccw_is_idal(ccw)) {
kfree(p);
if ((!cp->orb.cmd.c64 || cp->orb.cmd.i2k) && ccw_is_idal(ccw))
return -EOPNOTSUPP;
}
/*
* We want to keep counting if the current CCW has the
@ -435,7 +421,6 @@ static int ccwchain_calc_length(u64 iova, struct channel_program *cp)
if (cnt == CCWCHAIN_LEN_MAX + 1)
cnt = -EINVAL;
kfree(p);
return cnt;
}
@ -461,7 +446,7 @@ static int ccwchain_handle_ccw(u32 cda, struct channel_program *cp)
struct ccwchain *chain;
int len, ret;
/* Get chain length. */
/* Copy the chain from cda to cp, and count the CCWs in it */
len = ccwchain_calc_length(cda, cp);
if (len < 0)
return len;

7
drivers/s390/cio/vfio_ccw_cp.h
View File

@ -16,6 +16,12 @@
#include "orb.h"
/*
* Max length for ccw chain.
* XXX: Limit to 256, need to check more?
*/
#define CCWCHAIN_LEN_MAX 256
/**
* struct channel_program - manage information for channel program
* @ccwchain_list: list head of ccwchains
@ -32,6 +38,7 @@ struct channel_program {
union orb orb;
struct device *mdev;
bool initialized;
struct ccw1 *guest_cp;
};
extern int cp_init(struct channel_program *cp, struct device *mdev,

7
drivers/s390/cio/vfio_ccw_drv.c
View File

@ -129,6 +129,11 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
if (!private)
return -ENOMEM;
private->cp.guest_cp = kcalloc(CCWCHAIN_LEN_MAX, sizeof(struct ccw1),
GFP_KERNEL);
if (!private->cp.guest_cp)
goto out_free;
private->io_region = kmem_cache_zalloc(vfio_ccw_io_region,
GFP_KERNEL | GFP_DMA);
if (!private->io_region)
@ -169,6 +174,7 @@ out_free:
kmem_cache_free(vfio_ccw_cmd_region, private->cmd_region);
if (private->io_region)
kmem_cache_free(vfio_ccw_io_region, private->io_region);
kfree(private->cp.guest_cp);
kfree(private);
return ret;
}
@ -185,6 +191,7 @@ static int vfio_ccw_sch_remove(struct subchannel *sch)
kmem_cache_free(vfio_ccw_cmd_region, private->cmd_region);
kmem_cache_free(vfio_ccw_io_region, private->io_region);
kfree(private->cp.guest_cp);
kfree(private);
return 0;