Re: [Xen-devel] [PATCH v3 02/27] x86/xen/MSI: Eliminate arch_msix_mask_irq() and arch_msi_mask_irq()

[Bjorn Helgaas <bhelgaas@xxxxxxxxxx>]

On Wed, Oct 15, 2014 at 11:06:50AM +0800, Yijing Wang wrote:
> Commit 0e4ccb1505a9 ("PCI: Add x86_msi.msi_mask_irq() and msix_mask_irq()")
> introduced two __weak arch functions arch_msix_mask_irq() and
> arch_msi_mask_irq() to work around a bug when running xen in x86.
> These two functions made msi code more complex. This patch reverts
> the commit and introduces a global flag to control msi mask action to
> avoid the bug. The patch is also preparation for using MSI chip framework
> instead of weak arch MSI functions in all platforms. Keep 
> default_msi_mask_irq()
> and default_msix_mask_irq() in linux/msi.h to make s390 MSI code compile
> happy, they will be removed in the later patch.

This patch is basically a revert of 0e4ccb1505a9 intermingled with the
addition of the new pci_msi_ignore_mask technique.

Can you please split this into two patches:

  - Add the pci_msi_ignore_mask stuff (alongside the existing way)
  - Revert 0e4ccb1505a9

I think that will make it easier to see what's going on.

> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
> CC: David Vrabel <david.vrabel@xxxxxxxxxx>
> CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
> Hi David and Konrad,
>    I dropped the Acked-by and tested-by, because this version has a
> lot changes compared to last. So, I guess you may want to check it again.
> ---
>  arch/x86/include/asm/x86_init.h |    3 ---
>  arch/x86/kernel/x86_init.c      |   10 ----------
>  arch/x86/pci/xen.c              |   14 ++------------
>  drivers/pci/msi.c               |   29 ++++++++++++-----------------
>  include/linux/msi.h             |    8 ++++++--
>  5 files changed, 20 insertions(+), 44 deletions(-)
> 
> diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
> index e45e4da..f58a9c7 100644
> --- a/arch/x86/include/asm/x86_init.h
> +++ b/arch/x86/include/asm/x86_init.h
> @@ -172,7 +172,6 @@ struct x86_platform_ops {
>  
>  struct pci_dev;
>  struct msi_msg;
> -struct msi_desc;
>  
>  struct x86_msi_ops {
>       int (*setup_msi_irqs)(struct pci_dev *dev, int nvec, int type);
> @@ -183,8 +182,6 @@ struct x86_msi_ops {
>       void (*teardown_msi_irqs)(struct pci_dev *dev);
>       void (*restore_msi_irqs)(struct pci_dev *dev);
>       int  (*setup_hpet_msi)(unsigned int irq, unsigned int id);
> -     u32 (*msi_mask_irq)(struct msi_desc *desc, u32 mask, u32 flag);
> -     u32 (*msix_mask_irq)(struct msi_desc *desc, u32 flag);
>  };
>  
>  struct IO_APIC_route_entry;
> diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
> index e48b674..234b072 100644
> --- a/arch/x86/kernel/x86_init.c
> +++ b/arch/x86/kernel/x86_init.c
> @@ -116,8 +116,6 @@ struct x86_msi_ops x86_msi = {
>       .teardown_msi_irqs      = default_teardown_msi_irqs,
>       .restore_msi_irqs       = default_restore_msi_irqs,
>       .setup_hpet_msi         = default_setup_hpet_msi,
> -     .msi_mask_irq           = default_msi_mask_irq,
> -     .msix_mask_irq          = default_msix_mask_irq,
>  };
>  
>  /* MSI arch specific hooks */
> @@ -140,14 +138,6 @@ void arch_restore_msi_irqs(struct pci_dev *dev)
>  {
>       x86_msi.restore_msi_irqs(dev);
>  }
> -u32 arch_msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag)
> -{
> -     return x86_msi.msi_mask_irq(desc, mask, flag);
> -}
> -u32 arch_msix_mask_irq(struct msi_desc *desc, u32 flag)
> -{
> -     return x86_msi.msix_mask_irq(desc, flag);
> -}
>  #endif
>  
>  struct x86_io_apic_ops x86_io_apic_ops = {
> diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
> index 093f5f4..e5b8b78 100644
> --- a/arch/x86/pci/xen.c
> +++ b/arch/x86/pci/xen.c
> @@ -394,14 +394,6 @@ static void xen_teardown_msi_irq(unsigned int irq)
>  {
>       xen_destroy_irq(irq);
>  }
> -static u32 xen_nop_msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag)
> -{
> -     return 0;
> -}
> -static u32 xen_nop_msix_mask_irq(struct msi_desc *desc, u32 flag)
> -{
> -     return 0;
> -}
>  #endif
>  
>  int __init pci_xen_init(void)
> @@ -425,8 +417,7 @@ int __init pci_xen_init(void)
>       x86_msi.setup_msi_irqs = xen_setup_msi_irqs;
>       x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
>       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;
>  }
> @@ -506,8 +497,7 @@ int __init pci_xen_initial_domain(void)
>       x86_msi.setup_msi_irqs = xen_initdom_setup_msi_irqs;
>       x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
>       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 ecb92a5..22e413c 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)
>  
> @@ -162,11 +163,11 @@ static inline __attribute_const__ u32 msi_mask(unsigned 
> x)
>   * reliably as devices without an INTx disable bit will then generate a
>   * level IRQ which will never be cleared.
>   */
> -u32 default_msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag)
> +u32 __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;
> @@ -176,14 +177,9 @@ u32 default_msi_mask_irq(struct msi_desc *desc, u32 
> mask, u32 flag)
>       return mask_bits;
>  }
>  
> -__weak u32 arch_msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag)
> -{
> -     return default_msi_mask_irq(desc, mask, flag);
> -}
> -
>  static void msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag)
>  {
> -     desc->masked = arch_msi_mask_irq(desc, mask, flag);
> +     desc->masked = __msi_mask_irq(desc, mask, flag);
>  }
>  
>  /*
> @@ -193,11 +189,15 @@ static void msi_mask_irq(struct msi_desc *desc, u32 
> mask, u32 flag)
>   * file.  This saves a few milliseconds when initialising devices with lots
>   * of MSI-X interrupts.
>   */
> -u32 default_msix_mask_irq(struct msi_desc *desc, u32 flag)
> +u32 __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;
> @@ -206,14 +206,9 @@ u32 default_msix_mask_irq(struct msi_desc *desc, u32 
> flag)
>       return mask_bits;
>  }
>  
> -__weak u32 arch_msix_mask_irq(struct msi_desc *desc, u32 flag)
> -{
> -     return default_msix_mask_irq(desc, flag);
> -}
> -
>  static void msix_mask_irq(struct msi_desc *desc, u32 flag)
>  {
> -     desc->masked = arch_msix_mask_irq(desc, flag);
> +     desc->masked = __msix_mask_irq(desc, flag);
>  }
>  
>  static void msi_set_mask_bit(struct irq_data *data, u32 flag)
> @@ -866,7 +861,7 @@ void pci_msi_shutdown(struct pci_dev *dev)
>       /* Return the device with MSI unmasked as initial states */
>       mask = msi_mask(desc->msi_attrib.multi_cap);
>       /* Keep cached state to be restored */
> -     arch_msi_mask_irq(desc, mask, ~mask);
> +     __msi_mask_irq(desc, mask, ~mask);
>  
>       /* Restore dev->irq to its default pin-assertion irq */
>       dev->irq = desc->msi_attrib.default_irq;
> @@ -964,7 +959,7 @@ void pci_msix_shutdown(struct pci_dev *dev)
>       /* Return the device with MSI-X masked as initial states */
>       list_for_each_entry(entry, &dev->msi_list, list) {
>               /* Keep cached states to be restored */
> -             arch_msix_mask_irq(entry, 1);
> +             __msix_mask_irq(entry, 1);
>       }
>  
>       msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
> diff --git a/include/linux/msi.h b/include/linux/msi.h
> index 44f4746..9ac1e3b 100644
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -10,6 +10,8 @@ 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;
> @@ -21,6 +23,8 @@ void __write_msi_msg(struct msi_desc *entry, struct msi_msg 
> *msg);
>  void read_msi_msg(unsigned int irq, struct msi_msg *msg);
>  void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
>  void write_msi_msg(unsigned int irq, struct msi_msg *msg);
> +u32 __msix_mask_irq(struct msi_desc *desc, u32 flag);
> +u32 __msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag);
>  
>  struct msi_desc {
>       struct {
> @@ -61,8 +65,8 @@ void arch_restore_msi_irqs(struct pci_dev *dev);
>  
>  void default_teardown_msi_irqs(struct pci_dev *dev);
>  void default_restore_msi_irqs(struct pci_dev *dev);
> -u32 default_msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag);
> -u32 default_msix_mask_irq(struct msi_desc *desc, u32 flag);
> +#define default_msi_mask_irq __msi_mask_irq
> +#define default_msix_mask_irq        __msix_mask_irq
>  
>  struct msi_chip {
>       struct module *owner;
> -- 
> 1.7.1
> 

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