On 2025/5/21 19:23, Roger Pau Monné wrote: > On Wed, May 21, 2025 at 07:00:37AM +0000, Chen, Jiqian wrote: >> On 2025/5/20 17:43, Roger Pau Monné wrote: >>> On Tue, May 20, 2025 at 11:14:27AM +0200, Jan Beulich wrote: >>>> On 20.05.2025 11:09, Roger Pau Monné wrote: >>>>> On Tue, May 20, 2025 at 08:40:28AM +0200, Jan Beulich wrote: >>>>>> On 09.05.2025 11:05, Jiqian Chen wrote: >>>>>>> When init_msi() fails, the previous new changes will hide MSI >>>>>>> capability, it can't rely on vpci_deassign_device() to remove >>>>>>> all MSI related resources anymore, those resources must be >>>>>>> removed in cleanup function of MSI. >>>>>> >>>>>> That's because vpci_deassign_device() simply isn't called anymore? >>>>>> Could do with wording along these lines then. But (also applicable >>>>>> to the previous patch) - doesn't this need to come earlier? And is >>>>>> it sufficient to simply remove the register intercepts? Don't you >>>>>> need to put in place ones dropping all writes and making all reads >>>>>> return either 0 or ~0 (covering in particular Dom0, while for DomU-s >>>>>> this may already be the case by default behavior)? >>>>> >>>>> For domUs this is already the default behavior. >>>>> >>>>> For dom0 I think it should be enough to hide the capability from the >>>>> linked list, but not hide all the capability related >>>>> registers. IMO a well behaved dom0 won't try to access capabilities >>>>> disconnected from the linked list, >>>> >>>> Just that I've seen drivers knowing where their device has certain >>>> capabilities, thus not bothering to look up the respective >>>> capability. >>> >>> OK, so let's make the control register read-only in case of failure. >>> >>> If MSI(-X) is already enabled we should also make the entries >>> read-only, and while that's not very complicated for MSI, it does get >>> more convoluted for MSI-X. I'm fine with just making the control >>> register read-only for the time being. >> If I understand correctly, I need to avoid control register being removed >> and set the write hook of control register to be vpci_ignored_write and >> avoid freeing vpci->msi? >> >> " >> if ( !msi_pos || !vpci->msi ) >> return; >> >> + spin_lock(&vpci->lock); >> + control = vpci_get_register(vpci, msi_control_reg(msi_pos), 2); >> + if ( control ) >> + control->write = vpci_ignored_write; >> + spin_unlock(&vpci->lock); >> + >> if ( vpci->msi->masking ) >> end = msi_pending_bits_reg(msi_pos, vpci->msi->address64); >> else >> end = msi_mask_bits_reg(msi_pos, vpci->msi->address64) - 2; >> >> - size = end - msi_control_reg(msi_pos); >> + start = msi_control_reg(msi_pos) + 2; >> + size = end - start; >> >> - vpci_remove_registers(vpci, msi_control_reg(msi_pos), size); >> - XFREE(vpci->msi); >> + vpci_remove_registers(vpci, start, size); > > I think you want to first purge all the MSI range, and then add the > control register, also you want to keep the XFREE(), and set the > register as: Understood.
> > vpci_add_register(vpci, vpci_hw_read16, NULL, msi_control_reg(msi_pos), > 2, NULL); And one more question, how do I process return value of vpci_add_register since definition of cleanup hook is "void"? Print a error message if fail? > > So that you make it strictly hardware read-only, and not use the data > in vpci->msi. > > Regards, Roger. -- Best regards, Jiqian Chen.
