Fam Zheng <famz@xxxxxxxxxx> writes:
> On Sun, 03/29 17:04, Michael S. Tsirkin wrote:
>> commit d5dea7d95c48d7bc951cee4910a7fd9c0cd26fb0
>> "PCI: msi: Disable msi interrupts when we initialize a pci device"
>> fixes kexec when the booting kernel does not enable msi interupts.
>>
>> Unfortunately the relevant functionality is in msi.c so it isn't
>> compiled in when CONFIG_PCI_MSI is off, which means such configurations
>> would still get interrupt storms.
>>
>> Fix by moving part of the functionality probe.c, and compiling it
>> unconditionally.
>
> Reviewed-by: Fam Zheng <famz@xxxxxxxxxx>
Acked-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
I am a little surprised that there are systems that compile out MSI
support, but I do remember the problem being a limitation of the code
when wrote it and given how nasty screaming irqs are during boot up
it seems well worth it to have a little extra code to turn them off.
Eric
>> Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
>> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
>> ---
>> drivers/pci/msi.c | 12 ------------
>> drivers/pci/probe.c | 16 ++++++++++++++++
>> 2 files changed, 16 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
>> index 9942f68..f66be86 100644
>> --- a/drivers/pci/msi.c
>> +++ b/drivers/pci/msi.c
>> @@ -1041,18 +1041,6 @@ EXPORT_SYMBOL(pci_msi_enabled);
>> void pci_msi_init_pci_dev(struct pci_dev *dev)
>> {
>> INIT_LIST_HEAD(&dev->msi_list);
>> -
>> - /* Disable the msi hardware to avoid screaming interrupts
>> - * during boot. This is the power on reset default so
>> - * usually this should be a noop.
>> - */
>> - dev->msi_cap = pci_find_capability(dev, PCI_CAP_ID_MSI);
>> - if (dev->msi_cap)
>> - pci_msi_set_enable(dev, 0);
>> -
>> - dev->msix_cap = pci_find_capability(dev, PCI_CAP_ID_MSIX);
>> - if (dev->msix_cap)
>> - pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
>> }
>>
>> /**
>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
>> index 8d2f400..50dd934 100644
>> --- a/drivers/pci/probe.c
>> +++ b/drivers/pci/probe.c
>> @@ -1483,10 +1483,26 @@ static struct pci_dev *pci_scan_device(struct pci_bus *bus, int devfn)
>> return dev;
>> }
>>
>> +static void pci_msi_setup_pci_dev(struct pci_dev *dev)
>> +{
>> + /* Disable the msi hardware to avoid screaming interrupts
>> + * during boot. This is the power on reset default so
>> + * usually this should be a noop.
>> + */
>> + dev->msi_cap = pci_find_capability(dev, PCI_CAP_ID_MSI);
>> + if (dev->msi_cap)
>> + pci_msi_set_enable(dev, 0);
>> +
>> + dev->msix_cap = pci_find_capability(dev, PCI_CAP_ID_MSIX);
>> + if (dev->msix_cap)
>> + pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
>> +}
>> +
>> static void pci_init_capabilities(struct pci_dev *dev)
>> {
>> /* MSI/MSI-X list */
>> pci_msi_init_pci_dev(dev);
>> + pci_msi_setup_pci_dev(dev);
>>
>> /* Buffers for saving PCIe and PCI-X capabilities */
>> pci_allocate_cap_save_buffers(dev);
>> --
>> MST
>>
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