| Message ID | 1456771254-17511-18-git-send-email-armbru@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Feb 29, 2016 at 7:40 PM, Markus Armbruster <armbru@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. > sure, feel free to split in a seperate patch with my Review-by. > * 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. I prefer that code related to msix remains within msix blocks if possible, improving readability imho. Furthermore, since the function is msix specific, I think it's worth keeping the "msix" in the name. Since ivshmem_msix_use() wasn't good enough for you, perhaps we need the full-blown ivshmem_msix_vectors_use() instead. > > Signed-off-by: Markus Armbruster <armbru@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); > > return 0; > } > -- > 2.4.3 > >
Marc-André Lureau <marcandre.lureau@gmail.com> writes: > On Mon, Feb 29, 2016 at 7:40 PM, Markus Armbruster <armbru@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. >> > > sure, feel free to split in a seperate patch with my Review-by. > >> * 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. > > I prefer that code related to msix remains within msix blocks if > possible, improving readability imho. > > Furthermore, since the function is msix specific, I think it's worth > keeping the "msix" in the name. Since ivshmem_msix_use() wasn't good > enough for you, perhaps we need the full-blown > ivshmem_msix_vectors_use() instead. "Vectors" means actually two related, but distinct things with ivshmem: * the communication channels to transmit interrupts among peers, and * the MSI-X vectors. You can have the former without the latter, with msi=off. I guess there are two views of the function, both reasonable: 1. Prepare usage of "vectors", i.e. either kind. Name the function ivshmem_msix_vectors_use(), and call it unconditionally. The fact that it does only MSI-X stuff is implementation detail. 2. Prepare usage of MSI-X vectors. Name the function ivshmem_msix_vectors_use() or similar, and calls it only when ivshmem_has_feature(s, IVSHMEM_MSI), for consistency with other MSI-X functions. You prefer 2, I prefer 1. But it's not a deal-breaker for me; if you feel strongly, I can do 2.
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); return 0; }
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 <armbru@redhat.com> --- hw/misc/ivshmem.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-)