Marc-André Lureau <marcandre.lur...@gmail.com> writes:
> Hi
>
> On Mon, Mar 7, 2016 at 8:25 PM, Markus Armbruster <arm...@redhat.com> wrote:
>> 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. Rename
>> ivshmem_use_msix() to ivshmem_vector_use(), replace msix_present()
>> by ivshmem_has_feature() there, and drop the redundant guards.
>>
>> Signed-off-by: Markus Armbruster <arm...@redhat.com>
>> ---
>> hw/misc/ivshmem.c | 22 +++++++++-------------
>> 1 file changed, 9 insertions(+), 13 deletions(-)
>>
>> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
>> index 7191914..cfea151 100644
>> --- a/hw/misc/ivshmem.c
>> +++ b/hw/misc/ivshmem.c
>> @@ -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);
>> }
>> @@ -712,13 +714,12 @@ 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_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)) {
>> + if (!ivshmem_has_feature(s, IVSHMEM_MSI)) {
>> return;
>> }
>>
>> @@ -733,7 +734,7 @@ static void ivshmem_reset(DeviceState *d)
>>
>> s->intrstatus = 0;
>> s->intrmask = 0;
>> - ivshmem_use_msix(s);
>> + ivshmem_vector_use(s);
>> }
>>
>> static int ivshmem_setup_interrupts(IVShmemState *s)
>> @@ -747,9 +748,9 @@ static int ivshmem_setup_interrupts(IVShmemState *s)
>> }
>>
>> IVSHMEM_DPRINTF("msix initialized (%d vectors)\n", s->vectors);
>> - ivshmem_use_msix(s);
>> }
>>
>> + ivshmem_vector_use(s);
>> return 0;
>> }
>>
>> @@ -1034,12 +1035,7 @@ static int ivshmem_pre_load(void *opaque)
>>
>> 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_vector_use(opaque);
>> return 0;
>> }
>>
>> @@ -1067,11 +1063,11 @@ 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);
>> } else {
>> s->intrstatus = qemu_get_be32(f);
>> s->intrmask = qemu_get_be32(f);
>> }
>> + ivshmem_vector_use(s);
>>
>
> Sorry I didn't reply to your previous mail (which was slightly
> confusing due to wrong naming), yes I think calling it
> ivshmem_msix_vectors_use() inside the msix block is better (#2 from
> your reply).
I'll give it a try and see how it comes out.
> Other than that
>
> Reviewed-by: Marc-André Lureau <marcandre.lur...@redhat.com>
Thanks!
