[Qemu-devel] Re: [PATCH 4/4] pci: interrupt disable bit support

[Isaku Yamahata]

On Wed, Nov 25, 2009 at 06:59:06PM +0200, Michael S. Tsirkin wrote:
> interrupt disable bit is mandatory in PCI spec,
> so we must implement it to be spec compliant.
> 
> Signed-off-by: Michael S. Tsirkin <address@hidden>
> ---
>  hw/pci.c |   57 ++++++++++++++++++++++++++++++++++++++++-----------------
>  hw/pci.h |    4 ++++
>  2 files changed, 44 insertions(+), 17 deletions(-)
> 
> diff --git a/hw/pci.c b/hw/pci.c
> index 844664b..3daae46 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -114,12 +114,43 @@ static void pci_update_irq_status(PCIDevice *dev)
>      }
>  }
>  
> +static void pci_change_irq_level(PCIDevice *pci_dev, int irq_num, int change)
> +{
> +    PCIBus *bus;
> +    for (;;) {
> +        bus = pci_dev->bus;
> +        irq_num = bus->map_irq(pci_dev, irq_num);
> +        if (bus->set_irq)
> +            break;
> +        pci_dev = bus->parent_dev;
> +    }
> +    bus->irq_count[irq_num] += change;
> +    bus->set_irq(bus->irq_opaque, irq_num, bus->irq_count[irq_num] != 0);

Let's use ! instead of != 0 for consistency.


> +}
> +
> +/* Update irq disabled field after config space change,
> + * assert/deassert interrupts if necessary. */
> +static void pci_update_irq_disabled(PCIDevice *d)
> +{
> +    int i;
> +    int disabled = !!(pci_get_word(d->config + PCI_COMMAND) &
> +                      PCI_COMMAND_INTX_DISABLE);
> +    if (disabled == d->irq_disabled)
> +        return;
> +    d->irq_disabled = disabled;
> +    for (i = 0; i < ARRAY_SIZE(d->irq_state); ++i) {
> +        int state = d->irq_state[i];
> +        pci_change_irq_level(d, i, disabled ? -state : state);
> +    }
> +}
> +

"if (!changed) return" check is in pci_set_irq().
So if d->irq_state[i] == 0, bus->set_irq() will be called again.
I suppose this isn't your intention.
I suppose !changed check should be in pci_change_irq_level() instead of 
pci_set_irq().


>  static void pci_device_reset(PCIDevice *dev)
>  {
>      int r;
>  
>      memset(dev->irq_state, 0, sizeof dev->irq_state);
>      dev->irq_status = 0;
> +    dev->irq_disabled = 0;
>      pci_update_irq_status(dev);
>      dev->config[PCI_COMMAND] &= ~(PCI_COMMAND_IO | PCI_COMMAND_MEMORY |
>                                    PCI_COMMAND_MASTER);
> @@ -345,6 +376,7 @@ int pci_device_load(PCIDevice *s, QEMUFile *f)
>      }
>      /* Restore the interrupt status bit. */
>      pci_update_irq_status(s);
> +    pci_update_irq_disabled(s);
>      return ret;
>  }
>  
> @@ -458,7 +490,8 @@ static void pci_init_wmask(PCIDevice *dev)
>      dev->wmask[PCI_CACHE_LINE_SIZE] = 0xff;
>      dev->wmask[PCI_INTERRUPT_LINE] = 0xff;
>      pci_set_word(dev->wmask + PCI_COMMAND,
> -                 PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER);
> +                 PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER |
> +                 PCI_COMMAND_INTX_DISABLE);
>  
>      memset(dev->wmask + PCI_CONFIG_HEADER_SIZE, 0xff,
>             config_size - PCI_CONFIG_HEADER_SIZE);
> @@ -903,26 +936,14 @@ void pci_default_write_config(PCIDevice *d, uint32_t 
> addr, uint32_t val, int l)
>          ranges_overlap(addr, l, PCI_ROM_ADDRESS1, 4) ||
>          range_covers_byte(addr, l, PCI_COMMAND))
>          pci_update_mappings(d);
> +
> +    if (range_covers_byte(addr, l, PCI_COMMAND))
> +        pci_update_irq_disabled(d);
>  }
>  
>  /***********************************************************/
>  /* generic PCI irq support */
>  
> -static void pci_change_irq_level(PCIDevice *pci_dev, int irq_num, int change)
> -{
> -    PCIBus *bus;
> -    for (;;) {
> -        bus = pci_dev->bus;
> -        irq_num = bus->map_irq(pci_dev, irq_num);
> -        if (bus->set_irq)
> -            break;
> -        pci_dev = bus->parent_dev;
> -    }
> -    bus->irq_count[irq_num] += change;
> -    bus->set_irq(bus->irq_opaque, irq_num, bus->irq_count[irq_num] != 0);
> -}
> -
> -
>  /* 0 <= irq_num <= 3. level must be 0 or 1 */
>  static void pci_set_irq(void *opaque, int irq_num, int level)
>  {
> @@ -935,7 +956,9 @@ static void pci_set_irq(void *opaque, int irq_num, int 
> level)
>  
>      pci_dev->irq_state[irq_num] = level;
>      pci_dev->irq_status += change;
> -    pci_update_irq_status(s);
> +    pci_update_irq_status(pci_dev);
> +    if (pci_dev->irq_disabled)
> +        return;
>      pci_change_irq_level(pci_dev, irq_num, change);
>  }
>  
> diff --git a/hw/pci.h b/hw/pci.h
> index c3f2c3f..994b8bc 100644
> --- a/hw/pci.h
> +++ b/hw/pci.h
> @@ -101,6 +101,7 @@ typedef struct PCIIORegion {
>  #define  PCI_COMMAND_IO              0x1     /* Enable response in I/O space 
> */
>  #define  PCI_COMMAND_MEMORY  0x2     /* Enable response in Memory space */
>  #define  PCI_COMMAND_MASTER  0x4     /* Enable bus master */
> +#define  PCI_COMMAND_INTX_DISABLE 0x400 /* INTx Emulation Disable */
>  #define PCI_STATUS              0x06    /* 16 bits */
>  #define  PCI_STATUS_INTERRUPT   0x08
>  #define PCI_REVISION_ID         0x08    /* 8 bits  */
> @@ -226,6 +227,9 @@ struct PCIDevice {
>      /* Sum of all irq levels. Used to implement irq status register. */
>      int irq_status;
>  
> +    /* Whether interrupts are disabled by command bit. */
> +    int irq_disabled;
> +
>      /* Capability bits */
>      uint32_t cap_present;
>  

-- 
yamahata