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[Qemu-devel] Re: [PATCH 4/4] pci: interrupt disable bit support
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] Re: [PATCH 4/4] pci: interrupt disable bit support |
Date: |
Thu, 26 Nov 2009 14:38:19 +0200 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
On Thu, Nov 26, 2009 at 11:53:16AM +0200, Michael S. Tsirkin wrote:
> On Thu, Nov 26, 2009 at 12:04:51PM +0900, Isaku Yamahata wrote:
> > 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.
> >
>
> This patch simply moves code, so it's better to keep it
> the same - this way git blame can find it.
> A separate patch to clean this might be a good idea.
>
> > > +}
> > > +
> > > +/* 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.
>
> Good catch, thanks!
Thinking about this more, in fact, it is harmless to call set_irq
with the same level as th old one, and this
is not on datapath.
So yes, this is the intention.
> > I suppose !changed check should be in pci_change_irq_level() instead of
> > pci_set_irq().
> >
>
> The fix is different: in fact pci_update_irq_disabled
> should never call pci_change_irq_level with change value 0.
> that -state should have been 1 - state.
> I'll fix this. Thanks!
In fact, you were right.
While calling pci_change_irq_level with change 0 is harmless,
it's cleaner to move the check within that function.
I'll do that.
> > > 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