On Thursday 08 January 2009, Kenji Kaneshige wrote:Rafael J. Wysocki wrote:From: Rafael J. Wysocki <rjw@xxxxxxx>I've posted the similar patch recently, which doesn't have this
If MSI-X interrupt mode is used by the PCI Express port driver, too
many vectors are allocated and it is not ensured that the right
vectors will be used for various services. Namely, the PCI Express
specification states that both PCI Express native PME and PCI Express
hotplug will always use the same MSI or MSI-X message for signalling
interrupts, which implies that the same vector will be used by both
of them. Also, the VC service does not use interrupts at all.
Moreover, is not clear which of the vectors allocated by
pci_enable_msix() will be used for PME and hotplug and which of them
will be used for AER if all of these services are configured.
For these reasons, rework the allocation of interrupts for PCI
Express ports so that at most two vectors are allocated and ensure
that the right vector will be used for the right purpose.
Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
---
drivers/pci/pcie/portdrv.h | 1 drivers/pci/pcie/portdrv_core.c | 155 +++++++++++++++++++++++++++++-----------
2 files changed, 117 insertions(+), 39 deletions(-)
Index: linux-2.6/drivers/pci/pcie/portdrv.h
===================================================================
--- linux-2.6.orig/drivers/pci/pcie/portdrv.h
+++ linux-2.6/drivers/pci/pcie/portdrv.h
@@ -25,6 +25,7 @@
#define PCIE_CAPABILITIES_REG 0x2
#define PCIE_SLOT_CAPABILITIES_REG 0x14
#define PCIE_PORT_DEVICE_MAXSERVICES 4
+#define PORT_MSI_VECTOR_MASK 0x1f
#define get_descriptor_id(type, service) (((type - 4) << 4) | service)
Index: linux-2.6/drivers/pci/pcie/portdrv_core.c
===================================================================
--- linux-2.6.orig/drivers/pci/pcie/portdrv_core.c
+++ linux-2.6/drivers/pci/pcie/portdrv_core.c
@@ -30,55 +30,120 @@ static void release_pcie_device(struct d
}
/**
+ * fix_up_vectors - ensure the right ordering of MSI-X interrupt vectors
+ * @dev: PCI Express port that is going to use the vectors
+ * @vectors: Array of interrupt vectors to check (2 entries)
+ *
+ * Return value:
+ * 0 on success, error code if the values read from config registers are not as
+ * expected
+ *
+ * If this function is called, we are going to use two interrupt vectors which
+ * may be different, but we have to make sure they are in the right order such
+ * that the vector to be used for PME and hotplug signalling is the first one.
+ *
+ * NOTE: The assumption here is that MSI message offset (with respect to the
+ * base Message Data) equal to N corresponds to index N in the array of vectors
+ * returned by pci_enable_msix().
+ */
assumption.
Actually, this assumption is in agreement with PCI Express Base Specification
2.0, which very clearly states in Section 7.8.2 that:
"[...] Interrupt Message Number – This field indicates which
MSI/MSI-X vector is used for the interrupt message generated in
association with any of the status bits of this Capability structure.
[...]
For MSI-X, the value in this field indicates which MSI-X Table
entry is used to generate the interrupt message. The entry must
be one of the first 32 entries even if the Function implements
more than 32 entries. For a given MSI-X implementation, the
entry must remain constant."
Well, I have to update the comment. :-)
Please take a look.
http://marc.info/?l=linux-pci&m=122992792507715&w=2
OK, thanks. I can easily change my patch to follow this behavior, although
I don't really think it's necessary given the above.
NOTE: I've confirmed MSI and INTx still work with my patch, but it
is not tested on the machine with MSI-X capable port, since I don't
have such environment.
I also have tested my patch with both MSI and INTx, but I also don't have
MSI-X capable root ports in any of my test boxes.