On 2014-07-20 21:48, Michael S. Tsirkin wrote: > On Sat, Jul 19, 2014 at 06:55:48PM +0200, Jan Kiszka wrote: >> From: Jan Kiszka <jan.kis...@siemens.com> >> >> The spec says (and real HW confirms this) that, if the bus master bit >> is 0, the device will not generate any PCI accesses. MSI and MSI-X >> messages fall among these. >> >> Signed-off-by: Jan Kiszka <jan.kis...@siemens.com> > > I guess an alternative is for callers to check before > invoking msi_notify. Please note is this is only option > when using e.g. irqfd, so this has some advantages. > Is there a specific device that is affected by this? > I would expect drivers to disable msi before clearing > bus master bit ...
This is about emulating conforming behaviour without touching each and
every device. I stumbled over this while playing with emulated vs. real
Intel HDA.
It may not be complete, but I think it's a step forward. Irqfd users
apparently have to do this themselves then, I didn't look into this. But
all the rest should not open-code this logic.
Jan
>
>> ---
>> hw/pci/msi.c | 4 ++++
>> hw/pci/msix.c | 4 ++++
>> 2 files changed, 8 insertions(+)
>>
>> diff --git a/hw/pci/msi.c b/hw/pci/msi.c
>> index a4a3040..36b651b 100644
>> --- a/hw/pci/msi.c
>> +++ b/hw/pci/msi.c
>> @@ -285,6 +285,10 @@ void msi_notify(PCIDevice *dev, unsigned int vector)
>> return;
>> }
>>
>> + if (!(pci_get_word(dev->config + PCI_COMMAND) & PCI_COMMAND_MASTER)) {
>> + return;
>> + }
>> +
>> msg = msi_get_message(dev, vector);
>>
>> MSI_DEV_PRINTF(dev,
>> diff --git a/hw/pci/msix.c b/hw/pci/msix.c
>> index 5c49bfc..c77ae7d 100644
>> --- a/hw/pci/msix.c
>> +++ b/hw/pci/msix.c
>> @@ -437,6 +437,10 @@ void msix_notify(PCIDevice *dev, unsigned vector)
>> return;
>> }
>>
>> + if (!(pci_get_word(dev->config + PCI_COMMAND) & PCI_COMMAND_MASTER)) {
>> + return;
>> + }
>> +
>> msg = msix_get_message(dev, vector);
>>
>> stl_le_phys(&address_space_memory, msg.address, msg.data);
>> --
>> 1.8.1.1.298.ge7eed54
>>
>
>
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