diff options
| author | Marc Zyngier <maz@kernel.org> | 2025-05-13 17:31:42 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2025-05-14 12:36:41 +0200 |
| commit | 1396e89e09f00deb816e5f4a176d71d554922292 (patch) | |
| tree | 6d497bd28611de133f993563087d7cc938a9e01b /include/linux/msi.h | |
| parent | 713335b6ee29f0045737a1ddfc685bc6040d4baf (diff) | |
genirq/msi: Move prepare() call to per-device allocation
The current device MSI infrastructure is subtly broken, as it will issue an
.msi_prepare() callback into the MSI controller driver every time it needs
to allocate an MSI. That's pretty wrong, as the contract (or unwarranted
assumption, depending who you ask) between the MSI controller and the core
code is that .msi_prepare() is called exactly once per device.
This leads to some subtle breakage in some MSI controller drivers, as it
gives the impression that there are multiple endpoints sharing a bus
identifier (RID in PCI parlance, DID for GICv3+). It implies that whatever
allocation the ITS driver (for example) has done on behalf of these devices
cannot be undone, as there is no way to track the shared state. This is
particularly bad for wire-MSI devices, for which .msi_prepare() is called
for each input line.
To address this issue, move the call to .msi_prepare() to take place at the
point of irq domain allocation, which is the only place that makes
sense. The msi_alloc_info_t structure is made part of the
msi_domain_template, so that its life-cycle is that of the domain as well.
Finally, the msi_info::alloc_data field is made to point at this allocation
tracking structure, ensuring that it is carried around the block.
This is all pretty straightforward, except for the non-device-MSI
leftovers, which still have to call .msi_prepare() at the old spot. One
day...
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250513163144.2215824-4-maz@kernel.org
Diffstat (limited to 'include/linux/msi.h')
| -rw-r--r-- | include/linux/msi.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/msi.h b/include/linux/msi.h index 63c23003ec9b..f4b94ccaf0c1 100644 --- a/include/linux/msi.h +++ b/include/linux/msi.h @@ -516,12 +516,14 @@ struct msi_domain_info { * @chip: Interrupt chip for this domain * @ops: MSI domain ops * @info: MSI domain info data + * @alloc_info: MSI domain allocation data (architecture specific) */ struct msi_domain_template { char name[48]; struct irq_chip chip; struct msi_domain_ops ops; struct msi_domain_info info; + msi_alloc_info_t alloc_info; }; /* |