Commit 082751e8 authored by Markus Armbruster's avatar Markus Armbruster
Browse files

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: default avatarMarkus Armbruster <armbru@redhat.com>
Message-Id: <1458066895-20632-20-git-send-email-armbru@redhat.com>
Reviewed-by: default avatarMarc-André Lureau <marcandre.lureau@redhat.com>
parent 434ad76d

hw/misc/ivshmem.c

+10 −12
Original line number Diff line number Diff line
@@ -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)) {

        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);