On Wed, Nov 22, 2017 at 11:46 AM, Marcel Apfelbaum <mar...@redhat.com> wrote: > Hi Ladi, > > On 20/11/2017 16:22, Ladi Prosek wrote: >> >> msix_mask_all() is supposed to invoke the release vector notifier if the >> state of the >> respective vector changed from unmasked or masked. > > > You mean from unmasked "to" masked right?
Yes, that's a typo. > The way it's currently called from >> >> msix_reset(), though, may result in calling the release notifier even if >> the vector >> is already masked. >> >> 1) msix_reset() clears out the msix_cap field and the msix_table. >> 2) msix_mask_all() runs with was_masked=false for all vectors because of >> 1), which >> results in calling the release notifier on all vectors. >> 3) if msix_reset() is subsequently called again, it goes through the same >> steps and >> calls the release notifier on all vectors again. >> > > As far as I can see in the code you are right.(very reset will trigger the > release notifiers > again) > >> This commit moves msix_mask_all() up so it runs before the device state is >> lost. > > > OK > >> And >> it adds a call to msix_update_function_masked() so that the device >> remembers that >> MSI-X is masked. >> > > msix_update_function_masked checks the msix is enabled or masked-off. > You are building on the fact the msix will not be enabled to set > "msix_function_masked" to "true", right? > (I just want to be sure I understand the patch) Correct. msix_enabled() will return false because we've just reset dev->config[dev->msix_cap + MSIX_CONTROL_OFFSET] I guess we could also simply assign true to it: dev->msix_function_masked = true; just like msix_init() does. >> This is likely a low impact issue, found while debugging an already broken >> device. It >> is however easy to fix and the expectation that the use and release >> notifier invocations >> are always balanced is very natural. >> > > I would leave it (maybe) out of 2.11 because it may expose other bugs > and we are after rc2 already. > > Adding Alex Williamson to see it does not affect device assignment, > other than that the patch looks OK to me. > > > Thanks, > Marcel > > >> Signed-off-by: Ladi Prosek <lpro...@redhat.com> >> --- >> hw/pci/msix.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/hw/pci/msix.c b/hw/pci/msix.c >> index c944c02135..34656de9b0 100644 >> --- a/hw/pci/msix.c >> +++ b/hw/pci/msix.c >> @@ -500,11 +500,12 @@ void msix_reset(PCIDevice *dev) >> return; >> } >> msix_clear_all_vectors(dev); >> + msix_mask_all(dev, dev->msix_entries_nr); >> dev->config[dev->msix_cap + MSIX_CONTROL_OFFSET] &= >> ~dev->wmask[dev->msix_cap + MSIX_CONTROL_OFFSET]; >> memset(dev->msix_table, 0, dev->msix_entries_nr * >> PCI_MSIX_ENTRY_SIZE); >> memset(dev->msix_pba, 0, QEMU_ALIGN_UP(dev->msix_entries_nr, 64) / >> 8); >> - msix_mask_all(dev, dev->msix_entries_nr); >> + msix_update_function_masked(dev); >> } >> /* PCI spec suggests that devices make it possible for software to >> configure >> >
