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Date: Mon, 26 Mar 2007 16:18:22 -0700
From: Mitch Williams <mitch.a.williams@...el.com>
To: linux-pci@...ey.karlin.mff.cuni.cz
Cc: gregkh@...e.de, ebiederm@...ssion.com,
linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
auke-jan.h.kok@...el.com
Subject: [PATCH 2.6.21-rc5] MSI: read-flush MSI-X table
This patch fixes a kernel bug which is triggered when using the
irqbalance daemon with MSI-X hardware.
Because both MSI-X interrupt messages and MSI-X table writes are posted,
it's possible for them to cross while in-flight. This results in
interrupts being received long after the kernel thinks they're disabled,
and in interrupts being sent to stale vectors after rebalancing.
This patch performs a read flush after writes to the MSI-X table for
enable/disable and rebalancing operations. Because this is an expensive
operation, we do not perform the read flush after mask/unmask
operations. Hardware which supports MSI-X typically also supports some
sort of interrupt moderation, so a read-flush is not necessary for
mask/unmask operations.
This patch has been validated with (unreleased) network hardware which
uses MSI-X.
Generated from 2.6.21-rc4; applies cleanly to 2.6.21-rc5.
Signed-off-by: Mitch Williams <mitch.a.williams@...el.com>
diff -urpN -X dontdiff linux-2.6.21-rc4-clean/arch/i386/kernel/io_apic.c linux-2.6.21-rc4/arch/i386/kernel/io_apic.c
--- linux-2.6.21-rc4-clean/arch/i386/kernel/io_apic.c 2007-03-19 16:16:30.000000000 -0700
+++ linux-2.6.21-rc4/arch/i386/kernel/io_apic.c 2007-03-19 16:24:05.000000000 -0700
@@ -2594,6 +2594,8 @@ static void set_msi_irq_affinity(unsigne
*/
static struct irq_chip msi_chip = {
.name = "PCI-MSI",
+ .enable = enable_msi_irq,
+ .disable = disable_msi_irq,
.unmask = unmask_msi_irq,
.mask = mask_msi_irq,
.ack = ack_ioapic_irq,
diff -urpN -X dontdiff linux-2.6.21-rc4-clean/arch/ia64/kernel/msi_ia64.c linux-2.6.21-rc4/arch/ia64/kernel/msi_ia64.c
--- linux-2.6.21-rc4-clean/arch/ia64/kernel/msi_ia64.c 2007-03-19 16:16:30.000000000 -0700
+++ linux-2.6.21-rc4/arch/ia64/kernel/msi_ia64.c 2007-03-19 16:24:05.000000000 -0700
@@ -121,6 +121,8 @@ static int ia64_msi_retrigger_irq(unsign
*/
static struct irq_chip ia64_msi_chip = {
.name = "PCI-MSI",
+ .enable = enable_msi_irq,
+ .disable = disable_msi_irq,
.mask = mask_msi_irq,
.unmask = unmask_msi_irq,
.ack = ia64_ack_msi_irq,
diff -urpN -X dontdiff linux-2.6.21-rc4-clean/arch/ia64/sn/kernel/msi_sn.c linux-2.6.21-rc4/arch/ia64/sn/kernel/msi_sn.c
--- linux-2.6.21-rc4-clean/arch/ia64/sn/kernel/msi_sn.c 2007-03-19 16:16:30.000000000 -0700
+++ linux-2.6.21-rc4/arch/ia64/sn/kernel/msi_sn.c 2007-03-19 16:24:05.000000000 -0700
@@ -224,6 +224,8 @@ static int sn_msi_retrigger_irq(unsigned
static struct irq_chip sn_msi_chip = {
.name = "PCI-MSI",
+ .enable = enable_msi_irq,
+ .disable = disable_msi_irq,
.mask = mask_msi_irq,
.unmask = unmask_msi_irq,
.ack = sn_ack_msi_irq,
diff -urpN -X dontdiff linux-2.6.21-rc4-clean/arch/x86_64/kernel/io_apic.c linux-2.6.21-rc4/arch/x86_64/kernel/io_apic.c
--- linux-2.6.21-rc4-clean/arch/x86_64/kernel/io_apic.c 2007-03-19 16:16:31.000000000 -0700
+++ linux-2.6.21-rc4/arch/x86_64/kernel/io_apic.c 2007-03-21 12:44:51.000000000 -0700
@@ -1942,6 +1942,7 @@ static void set_msi_irq_affinity(unsigne
if (cpus_empty(tmp))
return;
+ msix_flush_writes(irq);
if (assign_irq_vector(irq, mask))
return;
@@ -1956,6 +1957,7 @@ static void set_msi_irq_affinity(unsigne
msg.address_lo |= MSI_ADDR_DEST_ID(dest);
write_msi_msg(irq, &msg);
+ msix_flush_writes(irq);
irq_desc[irq].affinity = mask;
}
#endif /* CONFIG_SMP */
@@ -1966,6 +1968,8 @@ static void set_msi_irq_affinity(unsigne
*/
static struct irq_chip msi_chip = {
.name = "PCI-MSI",
+ .enable = enable_msi_irq,
+ .disable = disable_msi_irq,
.unmask = unmask_msi_irq,
.mask = mask_msi_irq,
.ack = ack_apic_edge,
diff -urpN -X dontdiff linux-2.6.21-rc4-clean/drivers/pci/msi.c linux-2.6.21-rc4/drivers/pci/msi.c
--- linux-2.6.21-rc4-clean/drivers/pci/msi.c 2007-03-19 16:16:32.000000000 -0700
+++ linux-2.6.21-rc4/drivers/pci/msi.c 2007-03-21 12:44:51.000000000 -0700
@@ -68,6 +68,29 @@ static void msix_set_enable(struct pci_d
}
}
+void msix_flush_writes(unsigned int irq)
+{
+ struct msi_desc *entry;
+
+ entry = get_irq_msi(irq);
+ BUG_ON(!entry || !entry->dev);
+ switch (entry->msi_attrib.type) {
+ case PCI_CAP_ID_MSI:
+ /* nothing to do */
+ break;
+ case PCI_CAP_ID_MSIX:
+ {
+ int offset = entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE +
+ PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET;
+ readl(entry->mask_base + offset);
+ break;
+ }
+ default:
+ BUG();
+ break;
+ }
+}
+
static void msi_set_mask_bit(unsigned int irq, int flag)
{
struct msi_desc *entry;
@@ -193,6 +216,17 @@ void unmask_msi_irq(unsigned int irq)
msi_set_mask_bit(irq, 0);
}
+void disable_msi_irq(unsigned int irq)
+{
+ msi_set_mask_bit(irq, 1);
+ msix_flush_writes(irq);
+}
+
+void enable_msi_irq(unsigned int irq)
+{
+ msi_set_mask_bit(irq, 0);
+ msix_flush_writes(irq);
+}
static int msi_free_irq(struct pci_dev* dev, int irq);
static int msi_init(void)
diff -urpN -X dontdiff linux-2.6.21-rc4-clean/include/linux/msi.h linux-2.6.21-rc4/include/linux/msi.h
--- linux-2.6.21-rc4-clean/include/linux/msi.h 2007-03-19 16:16:34.000000000 -0700
+++ linux-2.6.21-rc4/include/linux/msi.h 2007-03-21 12:44:51.000000000 -0700
@@ -10,8 +10,11 @@ struct msi_msg {
/* Helper functions */
extern void mask_msi_irq(unsigned int irq);
extern void unmask_msi_irq(unsigned int irq);
+extern void disable_msi_irq(unsigned int irq);
+extern void enable_msi_irq(unsigned int irq);
extern void read_msi_msg(unsigned int irq, struct msi_msg *msg);
extern void write_msi_msg(unsigned int irq, struct msi_msg *msg);
+extern void msix_flush_writes(unsigned int irq);
struct msi_desc {
struct {
-
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