Re: [Qemu-devel] [PATCH] msi/msix: added public API to set/get MSI message address, and data

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 21/06/12 17:39, Jan Kiszka wrote:
> On 2012-06-21 09:18, Alexey Kardashevskiy wrote:
>>
>> agrhhh. sha1 of the patch changed after rebasing :)
>>
>>
>>
>> Added (msi|msix)_(set|get)_message() function for whoever might
>> want to use them.
>>
>> Currently msi_notify()/msix_notify() write to these vectors to
>> signal the guest about an interrupt so the correct values have to
>> written there by the guest or QEMU.
>>
>> For example, POWER guest never initializes MSI/MSIX vectors, instead
>> it uses RTAS hypercalls. So in order to support MSIX for virtio-pci on
>> POWER we have to initialize MSI/MSIX message from QEMU.
>>
>> As only set* function are required by now, the "get" functions were added
>> or made public for a symmetry.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> ---
>>  hw/msi.c  |   29 +++++++++++++++++++++++++++++
>>  hw/msi.h  |    2 ++
>>  hw/msix.c |   11 ++++++++++-
>>  hw/msix.h |    3 +++
>>  4 files changed, 44 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/msi.c b/hw/msi.c
>> index 5233204..9ad84a4 100644
>> --- a/hw/msi.c
>> +++ b/hw/msi.c
>> @@ -105,6 +105,35 @@ static inline uint8_t msi_pending_off(const PCIDevice* dev, bool msi64bit)
>>      return dev->msi_cap + (msi64bit ? PCI_MSI_PENDING_64 : PCI_MSI_PENDING_32);
>>  }
>>  
>> +MSIMessage msi_get_message(PCIDevice *dev)
> 
> MSIMessage msi_get_message(PCIDevice *dev, unsigned vector)


Who/how/why is going to calculate the vector here?

> 
>> +{
>> +    uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
>> +    bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
>> +    MSIMessage msg;
>> +
>> +    if (msi64bit) {
>> +        msg.address = pci_get_quad(dev->config + msi_address_lo_off(dev));
>> +    } else {
>> +        msg.address = pci_get_long(dev->config + msi_address_lo_off(dev));
>> +    }
>> +    msg.data = pci_get_word(dev->config + msi_data_off(dev, msi64bit));
> 
> And I have this here in addition:
> 
>     unsigned int nr_vectors = msi_nr_vectors(flags);
>     ...
> 
>     if (nr_vectors > 1) {
>         msg.data &= ~(nr_vectors - 1);
>         msg.data |= vector;
>     }
> 
> See PCI spec and existing code.


What for? I really do not get it why someone might want to read something but not real value.
What PCI code should I look?


> 
>> +
>> +    return msg;
>> +}
>> +
>> +void msi_set_message(PCIDevice *dev, MSIMessage msg)
>> +{
>> +    uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
>> +    bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
>> +
>> +    if (msi64bit) {
>> +        pci_set_quad(dev->config + msi_address_lo_off(dev), msg.address);
>> +    } else {
>> +        pci_set_long(dev->config + msi_address_lo_off(dev), msg.address);
>> +    }
>> +    pci_set_word(dev->config + msi_data_off(dev, msi64bit), msg.data);
>> +}
>> +
>>  bool msi_enabled(const PCIDevice *dev)
>>  {
>>      return msi_present(dev) &&
>> diff --git a/hw/msi.h b/hw/msi.h
>> index 75747ab..4b0f4f8 100644
>> --- a/hw/msi.h
>> +++ b/hw/msi.h
>> @@ -31,6 +31,8 @@ struct MSIMessage {
>>  
>>  extern bool msi_supported;
>>  
>> +MSIMessage msi_get_message(PCIDevice *dev);
>> +void msi_set_message(PCIDevice *dev, MSIMessage msg);
>>  bool msi_enabled(const PCIDevice *dev);
>>  int msi_init(struct PCIDevice *dev, uint8_t offset,
>>               unsigned int nr_vectors, bool msi64bit, bool msi_per_vector_mask);
>> diff --git a/hw/msix.c b/hw/msix.c
>> index ded3c55..9e8d8bb 100644
>> --- a/hw/msix.c
>> +++ b/hw/msix.c
>> @@ -35,7 +35,7 @@
>>  #define MSIX_PAGE_PENDING (MSIX_PAGE_SIZE / 2)
>>  #define MSIX_MAX_ENTRIES 32
>>  
>> -static MSIMessage msix_get_message(PCIDevice *dev, unsigned vector)
>> +MSIMessage msix_get_message(PCIDevice *dev, unsigned vector)
>>  {
>>      uint8_t *table_entry = dev->msix_table_page + vector * PCI_MSIX_ENTRY_SIZE;
>>      MSIMessage msg;
>> @@ -45,6 +45,15 @@ static MSIMessage msix_get_message(PCIDevice *dev, unsigned vector)
>>      return msg;
>>  }
>>  
>> +void msix_set_message(PCIDevice *dev, int vector, struct MSIMessage msg)
>> +{
>> +    uint8_t *table_entry = dev->msix_table_page + vector * PCI_MSIX_ENTRY_SIZE;
>> +
>> +    pci_set_quad(table_entry + PCI_MSIX_ENTRY_LOWER_ADDR, msg.address);
>> +    pci_set_long(table_entry + PCI_MSIX_ENTRY_DATA, msg.data);
>> +    table_entry[PCI_MSIX_ENTRY_VECTOR_CTRL] &= ~PCI_MSIX_ENTRY_CTRL_MASKBIT;
>> +}
>> +
>>  /* Add MSI-X capability to the config space for the device. */
>>  /* Given a bar and its size, add MSI-X table on top of it
>>   * and fill MSI-X capability in the config space.
>> diff --git a/hw/msix.h b/hw/msix.h
>> index 50aee82..3374cf8 100644
>> --- a/hw/msix.h
>> +++ b/hw/msix.h
>> @@ -4,6 +4,9 @@
>>  #include "qemu-common.h"
>>  #include "pci.h"
>>  
>> +MSIMessage msix_get_message(PCIDevice *dev, unsigned vector);
>> +void msix_set_message(PCIDevice *dev, int vector, MSIMessage msg);
>> +
>>  int msix_init(PCIDevice *pdev, unsigned short nentries,
>>                MemoryRegion *bar,
>>                unsigned bar_nr, unsigned bar_size);
>>
> 
> General remark: You will make the life of the maintainers easier by
> formatting your patch in a way that a clean merge via git works without
> hand-editing. E.g. this patch was no scissor line (---8<--- etc.)
> between introductory text and the patch description. And the subject is
> not "[PATCH] ...".

In general you're right.
I just kept in mind that this patch will be rejected anyway.


-- 
Alexey