* [PATCH] vfio/pci: make MSI handling optional @ 2014-10-09 8:40 Arnd Bergmann 2014-10-13 8:50 ` Alex Williamson 0 siblings, 1 reply; 5+ messages in thread From: Arnd Bergmann @ 2014-10-09 8:40 UTC (permalink / raw) To: Alex Williamson Cc: kvm, Gavin Shan, Wen Xiong, linux-kernel, linux-arm-kernel A recent bug fix to the MSIx handling in vfio added references to functions that may not be defined if MSI is disabled in the kernel, resulting in this link error: drivers/built-in.o: In function `vfio_msi_set_vector_signal': :(.text+0x450808): undefined reference to `get_cached_msi_msg' :(.text+0x45080c): undefined reference to `write_msi_msg' >From what I can tell, all the MSI specific ioctl handling can be made optional in this case, which also reduces the code size for the vfo driver. This patches does so using a build-time IS_ENABLED() check, which leaves all the build coverage testing present but avoids the link error. A side-effect of this is that the driver now returns -ENOTTY instead of -EINVAL if user space calls VFIO_PCI_MSI_IRQ_INDEX on a kernel without MSI support, which seems to be the best behavior, but the approach could easily be changed if we want to preserve the existing behavior for compatibility reasons. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Fixes: b8f02af096b1 ("vfio/pci: Restore MSIx message prior to enabling") --- Found using randconfig build testing on ARM. diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c index 553212f037c3..1117f96b8556 100644 --- a/drivers/vfio/pci/vfio_pci_intrs.c +++ b/drivers/vfio/pci/vfio_pci_intrs.c @@ -827,6 +827,9 @@ int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags, break; case VFIO_PCI_MSI_IRQ_INDEX: case VFIO_PCI_MSIX_IRQ_INDEX: + if (!IS_ENABLED(CONFIG_PCI_MSI)) + break; + switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) { case VFIO_IRQ_SET_ACTION_MASK: case VFIO_IRQ_SET_ACTION_UNMASK: ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] vfio/pci: make MSI handling optional 2014-10-09 8:40 [PATCH] vfio/pci: make MSI handling optional Arnd Bergmann @ 2014-10-13 8:50 ` Alex Williamson 2014-10-13 11:02 ` Arnd Bergmann 2017-02-14 21:53 ` [PATCH] genirq/msi: add stubs for get_cached_msi_msg/pci_write_msi_msg Arnd Bergmann 0 siblings, 2 replies; 5+ messages in thread From: Alex Williamson @ 2014-10-13 8:50 UTC (permalink / raw) To: Arnd Bergmann; +Cc: kvm, Gavin Shan, Wen Xiong, linux-kernel, linux-arm-kernel On Thu, 2014-10-09 at 10:40 +0200, Arnd Bergmann wrote: > A recent bug fix to the MSIx handling in vfio added references > to functions that may not be defined if MSI is disabled in the kernel, > resulting in this link error: > > drivers/built-in.o: In function `vfio_msi_set_vector_signal': > :(.text+0x450808): undefined reference to `get_cached_msi_msg' > :(.text+0x45080c): undefined reference to `write_msi_msg' > > From what I can tell, all the MSI specific ioctl handling can > be made optional in this case, which also reduces the code size > for the vfo driver. This patches does so using a build-time > IS_ENABLED() check, which leaves all the build coverage testing > present but avoids the link error. > > A side-effect of this is that the driver now returns -ENOTTY instead > of -EINVAL if user space calls VFIO_PCI_MSI_IRQ_INDEX on a kernel > without MSI support, which seems to be the best behavior, but > the approach could easily be changed if we want to preserve the > existing behavior for compatibility reasons. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > Fixes: b8f02af096b1 ("vfio/pci: Restore MSIx message prior to enabling") > --- Why wouldn't we handle this with stubs for `get_cached_msi_msg' and `write_msi_msg'? We're really not talking about much code that might get removed by the compiler with this static branch and and it seems like a rather non-standard mechanism. The count of MSI/X IRQs advertised to the user should be zero without CONFIG_MSI and later range checks would prevent calls to these functions for invalid indexes, so it's a bit of a random test in the code flow. Thanks, Alex > Found using randconfig build testing on ARM. > > diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c > index 553212f037c3..1117f96b8556 100644 > --- a/drivers/vfio/pci/vfio_pci_intrs.c > +++ b/drivers/vfio/pci/vfio_pci_intrs.c > @@ -827,6 +827,9 @@ int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags, > break; > case VFIO_PCI_MSI_IRQ_INDEX: > case VFIO_PCI_MSIX_IRQ_INDEX: > + if (!IS_ENABLED(CONFIG_PCI_MSI)) > + break; > + > switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) { > case VFIO_IRQ_SET_ACTION_MASK: > case VFIO_IRQ_SET_ACTION_UNMASK: > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] vfio/pci: make MSI handling optional 2014-10-13 8:50 ` Alex Williamson @ 2014-10-13 11:02 ` Arnd Bergmann 2017-02-14 21:53 ` [PATCH] genirq/msi: add stubs for get_cached_msi_msg/pci_write_msi_msg Arnd Bergmann 1 sibling, 0 replies; 5+ messages in thread From: Arnd Bergmann @ 2014-10-13 11:02 UTC (permalink / raw) To: linux-arm-kernel Cc: Alex Williamson, Wen Xiong, Gavin Shan, kvm, linux-kernel On Monday 13 October 2014 02:50:08 Alex Williamson wrote: > > Why wouldn't we handle this with stubs for `get_cached_msi_msg' and > `write_msi_msg'? We're really not talking about much code that might > get removed by the compiler with this static branch and and it seems > like a rather non-standard mechanism. The count of MSI/X IRQs > advertised to the user should be zero without CONFIG_MSI and later range > checks would prevent calls to > these functions for invalid indexes, so it's a bit of a random test in > the code flow. Thanks, > That's fine with me too. Arnd ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] genirq/msi: add stubs for get_cached_msi_msg/pci_write_msi_msg @ 2017-02-14 21:53 ` Arnd Bergmann 2017-02-16 14:34 ` [tip:irq/core] genirq/msi: Add " tip-bot for Arnd Bergmann 0 siblings, 1 reply; 5+ messages in thread From: Arnd Bergmann @ 2017-02-14 21:53 UTC (permalink / raw) To: Thomas Gleixner Cc: Alex Williamson, Arnd Bergmann, Marc Zyngier, Bjorn Helgaas, Bart Van Assche, linux-kernel A bug fix to the MSIx handling in vfio added references to functions that may not be defined if MSI is disabled in the kernel, resulting in this link error: drivers/built-in.o: In function `vfio_msi_set_vector_signal': :(.text+0x450808): undefined reference to `get_cached_msi_msg' :(.text+0x45080c): undefined reference to `write_msi_msg' As suggested by Alex Williamson, this adds stub implementations for get_cached_msi_msg() and pci_write_msi_msg(). In case this bugfix gets backported, please note that the #ifdef has changed over time, originally both functions were implemented in drivers/pci/msi.c and controlled by CONFIG_PCI_MSI, while nowadays get_cached_msi_msg() is part of the generic MSI support and can be used without PCI. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Fixes: b8f02af096b1 ("vfio/pci: Restore MSIx message prior to enabling") Link: https://lkml.org/lkml/2014/10/13/124 --- I had a workaround for this hidden in my randconfig tree but have now stumbled over it again, sorry for not following up a couple of years earlier. --- include/linux/msi.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/include/linux/msi.h b/include/linux/msi.h index 0db320b7bb15..a83b84ff70e5 100644 --- a/include/linux/msi.h +++ b/include/linux/msi.h @@ -17,7 +17,13 @@ struct msi_desc; struct pci_dev; struct platform_msi_priv_data; void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg); +#ifdef CONFIG_GENERIC_MSI_IRQ void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg); +#else +static inline void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg) +{ +} +#endif typedef void (*irq_write_msi_msg_t)(struct msi_desc *desc, struct msi_msg *msg); @@ -116,11 +122,15 @@ struct msi_desc { struct pci_dev *msi_desc_to_pci_dev(struct msi_desc *desc); void *msi_desc_to_pci_sysdata(struct msi_desc *desc); +void pci_write_msi_msg(unsigned int irq, struct msi_msg *msg); #else /* CONFIG_PCI_MSI */ static inline void *msi_desc_to_pci_sysdata(struct msi_desc *desc) { return NULL; } +static inline void pci_write_msi_msg(unsigned int irq, struct msi_msg *msg) +{ +} #endif /* CONFIG_PCI_MSI */ struct msi_desc *alloc_msi_entry(struct device *dev, int nvec, @@ -128,7 +138,6 @@ struct msi_desc *alloc_msi_entry(struct device *dev, int nvec, void free_msi_entry(struct msi_desc *entry); void __pci_read_msi_msg(struct msi_desc *entry, struct msi_msg *msg); void __pci_write_msi_msg(struct msi_desc *entry, struct msi_msg *msg); -void pci_write_msi_msg(unsigned int irq, struct msi_msg *msg); u32 __pci_msix_desc_mask_irq(struct msi_desc *desc, u32 flag); u32 __pci_msi_desc_mask_irq(struct msi_desc *desc, u32 mask, u32 flag); -- 2.9.0 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* [tip:irq/core] genirq/msi: Add stubs for get_cached_msi_msg/pci_write_msi_msg 2017-02-14 21:53 ` [PATCH] genirq/msi: add stubs for get_cached_msi_msg/pci_write_msi_msg Arnd Bergmann @ 2017-02-16 14:34 ` tip-bot for Arnd Bergmann 0 siblings, 0 replies; 5+ messages in thread From: tip-bot for Arnd Bergmann @ 2017-02-16 14:34 UTC (permalink / raw) To: linux-tip-commits Cc: bart.vanassche, hpa, mingo, bhelgaas, tglx, linux-kernel, arnd, alex.williamson, marc.zyngier Commit-ID: 2f44e29cef006a4b0a4ecf7d4c5aac7d0fbb505c Gitweb: http://git.kernel.org/tip/2f44e29cef006a4b0a4ecf7d4c5aac7d0fbb505c Author: Arnd Bergmann <arnd@arndb.de> AuthorDate: Tue, 14 Feb 2017 22:53:12 +0100 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Thu, 16 Feb 2017 15:32:19 +0100 genirq/msi: Add stubs for get_cached_msi_msg/pci_write_msi_msg A bug fix to the MSIx handling in vfio added references to functions that may not be defined if MSI is disabled in the kernel, resulting in this link error: drivers/built-in.o: In function `vfio_msi_set_vector_signal': :(.text+0x450808): undefined reference to `get_cached_msi_msg' :(.text+0x45080c): undefined reference to `write_msi_msg' As suggested by Alex Williamson, add stub implementations for get_cached_msi_msg() and pci_write_msi_msg(). In case this bugfix gets backported, please note that the #ifdef has changed over time, originally both functions were implemented in drivers/pci/msi.c and controlled by CONFIG_PCI_MSI, while nowadays get_cached_msi_msg() is part of the generic MSI support and can be used without PCI. Fixes: b8f02af096b1 ("vfio/pci: Restore MSIx message prior to enabling") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Bart Van Assche <bart.vanassche@sandisk.com> Link: http://lkml.kernel.org/r/1413190208.4202.34.camel@ul30vt.home Link: http://lkml.kernel.org/r/20170214215343.3307861-1-arnd@arndb.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- include/linux/msi.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/include/linux/msi.h b/include/linux/msi.h index 0db320b..a83b84f 100644 --- a/include/linux/msi.h +++ b/include/linux/msi.h @@ -17,7 +17,13 @@ struct msi_desc; struct pci_dev; struct platform_msi_priv_data; void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg); +#ifdef CONFIG_GENERIC_MSI_IRQ void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg); +#else +static inline void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg) +{ +} +#endif typedef void (*irq_write_msi_msg_t)(struct msi_desc *desc, struct msi_msg *msg); @@ -116,11 +122,15 @@ struct msi_desc { struct pci_dev *msi_desc_to_pci_dev(struct msi_desc *desc); void *msi_desc_to_pci_sysdata(struct msi_desc *desc); +void pci_write_msi_msg(unsigned int irq, struct msi_msg *msg); #else /* CONFIG_PCI_MSI */ static inline void *msi_desc_to_pci_sysdata(struct msi_desc *desc) { return NULL; } +static inline void pci_write_msi_msg(unsigned int irq, struct msi_msg *msg) +{ +} #endif /* CONFIG_PCI_MSI */ struct msi_desc *alloc_msi_entry(struct device *dev, int nvec, @@ -128,7 +138,6 @@ struct msi_desc *alloc_msi_entry(struct device *dev, int nvec, void free_msi_entry(struct msi_desc *entry); void __pci_read_msi_msg(struct msi_desc *entry, struct msi_msg *msg); void __pci_write_msi_msg(struct msi_desc *entry, struct msi_msg *msg); -void pci_write_msi_msg(unsigned int irq, struct msi_msg *msg); u32 __pci_msix_desc_mask_irq(struct msi_desc *desc, u32 flag); u32 __pci_msi_desc_mask_irq(struct msi_desc *desc, u32 mask, u32 flag); ^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2017-02-16 14:34 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2014-10-09 8:40 [PATCH] vfio/pci: make MSI handling optional Arnd Bergmann 2014-10-13 8:50 ` Alex Williamson 2014-10-13 11:02 ` Arnd Bergmann 2017-02-14 21:53 ` [PATCH] genirq/msi: add stubs for get_cached_msi_msg/pci_write_msi_msg Arnd Bergmann 2017-02-16 14:34 ` [tip:irq/core] genirq/msi: Add " tip-bot for Arnd Bergmann
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