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Subject[PATCH 4.4 123/193] genirq/msi: Add stubs for get_cached_msi_msg/pci_write_msi_msg
4.4-stable review patch.  If anyone has any objections, please let me know.


From: Arnd Bergmann <>

commit 2f44e29cef006a4b0a4ecf7d4c5aac7d0fbb505c upstream.

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 <>
Cc: Marc Zyngier <>
Cc: Alex Williamson <>
Cc: Bjorn Helgaas <>
Cc: Bart Van Assche <>
Signed-off-by: Thomas Gleixner <>
Signed-off-by: Greg Kroah-Hartman <>

include/linux/msi.h | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

--- 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);
void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
+static inline void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg)

typedef void (*irq_write_msi_msg_t)(struct msi_desc *desc,
struct msi_msg *msg);
@@ -105,18 +111,21 @@ 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);
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);

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