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ivshmem: Clean up MSI-X conditions 

There are three predicates related to MSI-X:

* ivshmem_has_feature(s, IVSHMEM_MSI) is true unless the non-MSI-X
  variant of the device is selected with msi=off.

* msix_present() is true when the device has the PCI capability MSI-X.
  It's initially false, and becomes true during successful realize of
  the MSI-X variant of the device.  Thus, it's the same as
  ivshmem_has_feature(s, IVSHMEM_MSI) for realized devices.

* msix_enabled() is true when msix_present() is true and guest software
  has enabled MSI-X.

Code that differs between the non-MSI-X and the MSI-X variant of the
device needs to be guarded by ivshmem_has_feature(s, IVSHMEM_MSI) or
by msix_present(), except the latter works only for realized devices.

Code that depends on whether MSI-X is in use needs to be guarded with
msix_enabled().

Code review led me to two minor messes:

* ivshmem_vector_notify() calls msix_notify() even when
  !msix_enabled(), unlike most other MSI-X-capable devices.  As far as
  I can tell, msix_notify() does nothing when !msix_enabled().  Add
  the guard anyway.

* Most callers of ivshmem_use_msix() guard it with
  ivshmem_has_feature(s, IVSHMEM_MSI).  Not necessary, because
  ivshmem_use_msix() does nothing when !msix_present().  That's
  ivshmem's only use of msix_present(), though.  Guard it
  consistently, and drop the now redundant msix_present() check.
  While there, rename ivshmem_use_msix() to ivshmem_msix_vector_use().

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1458066895-20632-20-git-send-email-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
This commit is contained in:
Markus Armbruster 2016-03-15 19:34:34 +01:00
parent 434ad76db5
commit 082751e82b
1 changed files with 10 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
hw/misc/ivshmem.c
View File

@ -274,7 +274,9 @@ static void ivshmem_vector_notify(void *opaque)
IVSHMEM_DPRINTF("interrupt on vector %p %d\n", pdev, vector);
if (ivshmem_has_feature(s, IVSHMEM_MSI)) {
msix_notify(pdev, vector);
if (msix_enabled(pdev)) {
msix_notify(pdev, vector);
}
} else {
ivshmem_IntrStatus_write(s, 1);
}
@ -713,16 +715,11 @@ static void ivshmem_check_version(void *opaque, const uint8_t * buf, int size)
/* Select the MSI-X vectors used by device.
* ivshmem maps events to vectors statically, so
* we just enable all vectors on init and after reset. */
static void ivshmem_use_msix(IVShmemState * s)
static void ivshmem_msix_vector_use(IVShmemState *s)
{
PCIDevice *d = PCI_DEVICE(s);
int i;
IVSHMEM_DPRINTF("%s, msix present: %d\n", __func__, msix_present(d));
if (!msix_present(d)) {
return;
}
for (i = 0; i < s->vectors; i++) {
msix_vector_use(d, i);
}
@ -734,7 +731,9 @@ static void ivshmem_reset(DeviceState *d)
s->intrstatus = 0;
s->intrmask = 0;
ivshmem_use_msix(s);
if (ivshmem_has_feature(s, IVSHMEM_MSI)) {
ivshmem_msix_vector_use(s);
}
}
static int ivshmem_setup_interrupts(IVShmemState *s)
@ -748,7 +747,7 @@ static int ivshmem_setup_interrupts(IVShmemState *s)
}
IVSHMEM_DPRINTF("msix initialized (%d vectors)\n", s->vectors);
ivshmem_use_msix(s);
ivshmem_msix_vector_use(s);
}
return 0;
@ -1040,9 +1039,8 @@ static int ivshmem_post_load(void *opaque, int version_id)
IVShmemState *s = opaque;
if (ivshmem_has_feature(s, IVSHMEM_MSI)) {
ivshmem_use_msix(s);
ivshmem_msix_vector_use(s);
}
return 0;
}
@ -1070,7 +1068,7 @@ static int ivshmem_load_old(QEMUFile *f, void *opaque, int version_id)
if (ivshmem_has_feature(s, IVSHMEM_MSI)) {
msix_load(pdev, f);
ivshmem_use_msix(s);
ivshmem_msix_vector_use(s);
} else {
s->intrstatus = qemu_get_be32(f);
s->intrmask = qemu_get_be32(f);