[Xen-devel] [PATCH 1/3] x86/xen: Introduce a global flag to fix the MSI mask bug

[Yijing Wang <wangyijing@xxxxxxxxxx>]

Commit 0e4ccb1505a9 ("PCI: Add x86_msi.msi_mask_irq() and msix_mask_irq()")
fixed MSI mask bug which may cause kernel crash. But the commit
made MSI code complex. Introduce a new global flag "pci_msi_ignore_mask"
to ignore MSI/MSI-X to fix this issue, it's a cleaner solution.
And the commit 0e4ccb1505a9 will be reverted in the later patch.

Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
CC: David Vrabel <david.vrabel@xxxxxxxxxx>
CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
CC: xen-devel@xxxxxxxxxxxxxxxxxxxx
---
 arch/x86/pci/xen.c  |    2 ++
 drivers/pci/msi.c   |    7 ++++++-
 include/linux/msi.h |    1 +
 3 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 093f5f4..5ef62ed 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -427,6 +427,7 @@ int __init pci_xen_init(void)
        x86_msi.teardown_msi_irqs = xen_teardown_msi_irqs;
        x86_msi.msi_mask_irq = xen_nop_msi_mask_irq;
        x86_msi.msix_mask_irq = xen_nop_msix_mask_irq;
+       pci_msi_ignore_mask = 1;
 #endif
        return 0;
 }
@@ -508,6 +509,7 @@ int __init pci_xen_initial_domain(void)
        x86_msi.restore_msi_irqs = xen_initdom_restore_msi_irqs;
        x86_msi.msi_mask_irq = xen_nop_msi_mask_irq;
        x86_msi.msix_mask_irq = xen_nop_msix_mask_irq;
+       pci_msi_ignore_mask = 1;
 #endif
        xen_setup_acpi_sci();
        __acpi_register_gsi = acpi_register_gsi_xen;
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 38511d9..ecb5f54 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -23,6 +23,7 @@
 #include "pci.h"
 
 static int pci_msi_enable = 1;
+int pci_msi_ignore_mask;
 
 #define msix_table_size(flags) ((flags & PCI_MSIX_FLAGS_QSIZE) + 1)
 
@@ -166,7 +167,7 @@ u32 default_msi_mask_irq(struct msi_desc *desc, u32 mask, 
u32 flag)
 {
        u32 mask_bits = desc->masked;
 
-       if (!desc->msi_attrib.maskbit)
+       if (pci_msi_ignore_mask || !desc->msi_attrib.maskbit)
                return 0;
 
        mask_bits &= ~mask;
@@ -198,6 +199,10 @@ u32 default_msix_mask_irq(struct msi_desc *desc, u32 flag)
        u32 mask_bits = desc->masked;
        unsigned offset = desc->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE +
                                                PCI_MSIX_ENTRY_VECTOR_CTRL;
+
+       if (pci_msi_ignore_mask)
+               return 0;
+
        mask_bits &= ~PCI_MSIX_ENTRY_CTRL_MASKBIT;
        if (flag)
                mask_bits |= PCI_MSIX_ENTRY_CTRL_MASKBIT;
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 44f4746..86dc501 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -10,6 +10,7 @@ struct msi_msg {
        u32     data;           /* 16 bits of msi message data */
 };
 
+extern int pci_msi_ignore_mask;
 /* Helper functions */
 struct irq_data;
 struct msi_desc;
-- 
1.7.1


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel