Re: [PATCH 5/9] pci-assign: Only calculate maximum MSI-X vector entries once

["Michael S. Tsirkin" <mst@redhat.com>]

On Sat, Jan 28, 2012 at 07:22:04AM -0700, Alex Williamson wrote:
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---

Why? Optimization?

>  hw/device-assignment.c |   17 +++++++----------
>  hw/device-assignment.h |    1 +
>  2 files changed, 8 insertions(+), 10 deletions(-)
> 
> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
> index 422ee00..af614d3 100644
> --- a/hw/device-assignment.c
> +++ b/hw/device-assignment.c
> @@ -971,20 +971,14 @@ static void assigned_dev_update_msi(PCIDevice *pci_dev)
>  static int assigned_dev_update_msix_mmio(PCIDevice *pci_dev)
>  {
>      AssignedDevice *adev = DO_UPCAST(AssignedDevice, dev, pci_dev);
> -    uint16_t entries_nr = 0, entries_max_nr;
> -    int pos = 0, i, r = 0;
> +    uint16_t entries_nr = 0;
> +    int i, r = 0;
>      struct kvm_assigned_msix_nr msix_nr;
>      struct kvm_assigned_msix_entry msix_entry;
>      MSIXTableEntry *entry = adev->msix_table;
>  
> -    pos = pci_find_capability(pci_dev, PCI_CAP_ID_MSIX);
> -
> -    entries_max_nr = *(uint16_t *)(pci_dev->config + pos + 2);
> -    entries_max_nr &= PCI_MSIX_FLAGS_QSIZE;
> -    entries_max_nr += 1;
> -
>      /* Get the usable entry number for allocating */
> -    for (i = 0; i < entries_max_nr; i++, entry++) {
> +    for (i = 0; i < adev->msix_max; i++, entry++) {
>          /* Ignore unused entry even it's unmasked */
>          if (entry->data == 0) {
>              continue;
> @@ -1012,7 +1006,7 @@ static int assigned_dev_update_msix_mmio(PCIDevice *pci_dev)
>      msix_entry.assigned_dev_id = msix_nr.assigned_dev_id;
>      entries_nr = 0;
>      entry = adev->msix_table;
> -    for (i = 0; i < entries_max_nr; i++, entry++) {
> +    for (i = 0; i < adev->msix_max; i++, entry++) {
>          if (entries_nr >= msix_nr.entry_nr)
>              break;
>          if (entry->data == 0) {
> @@ -1225,6 +1219,9 @@ static int assigned_device_pci_cap_init(PCIDevice *pci_dev)
>          bar_nr = msix_table_entry & PCI_MSIX_FLAGS_BIRMASK;
>          msix_table_entry &= ~PCI_MSIX_FLAGS_BIRMASK;
>          dev->msix_table_addr = pci_region[bar_nr].base_addr + msix_table_entry;
> +        dev->msix_max = pci_get_word(pci_dev->config + pos + PCI_MSIX_FLAGS);
> +        dev->msix_max &= PCI_MSIX_FLAGS_QSIZE;
> +        dev->msix_max += 1;
>      }
>  
>      /* Minimal PM support, nothing writable, device appears to NAK changes */
> diff --git a/hw/device-assignment.h b/hw/device-assignment.h
> index e229303..a909fb2 100644
> --- a/hw/device-assignment.h
> +++ b/hw/device-assignment.h
> @@ -119,6 +119,7 @@ typedef struct AssignedDevice {
>      struct kvm_irq_routing_entry *entry;
>      MSIXTableEntry *msix_table;
>      target_phys_addr_t msix_table_addr;
> +    uint16_t msix_max;
>      MemoryRegion mmio;
>      char *configfd_name;
>      int32_t bootindex;
> 
> --
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