Re: [PATCH 4/4] microvm: reconfigure irqs if second ioapic is available

[Igor Mammedov <imammedo@redhat.com>]

On Fri, 16 Oct 2020 13:43:28 +0200
Gerd Hoffmann <kraxel@redhat.com> wrote:

> Use GSI 16+ for PCIe (needs acpi_build_madt() tweak).
> Use GSI 24+ (second ioapic) for virtio-mmio.
> Use all irq lines of the second ioapic
> and allow up to 24 virtio-mmio devices.

description is  missing answer to question why it's done.


> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  hw/i386/acpi-common.c | 2 +-
>  hw/i386/microvm.c     | 6 +++++-
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/i386/acpi-common.c b/hw/i386/acpi-common.c
> index f0689392a39f..1653a8315248 100644
> --- a/hw/i386/acpi-common.c
> +++ b/hw/i386/acpi-common.c
> @@ -122,7 +122,7 @@ void acpi_build_madt(GArray *table_data, BIOSLinker *linker,
>          intsrcovr->flags  = cpu_to_le16(0); /* conforms to bus specifications */
>      }
>  
> -    for (i = 1; i < 16; i++) {
> +    for (i = 1; i < 24; i++) {
>          if (!(x86ms->pci_irq_mask & (1 << i))) {
>              /* No need for a INT source override structure. */
>              continue;
> diff --git a/hw/i386/microvm.c b/hw/i386/microvm.c
> index 15c3e078a4aa..70bb8a4e3954 100644
> --- a/hw/i386/microvm.c
> +++ b/hw/i386/microvm.c
> @@ -205,7 +205,11 @@ static void microvm_devices_init(MicrovmMachineState *mms)
>  
>      mms->virtio_irq_base = 5;
>      mms->virtio_num_transports = 8;
> -    if (x86_machine_is_acpi_enabled(x86ms)) {
> +    if (ioapic2) {
> +        mms->pcie_irq_base = 16;
> +        mms->virtio_irq_base = 24;
> +        mms->virtio_num_transports = 24;
> +    } else if (x86_machine_is_acpi_enabled(x86ms)) {
>          mms->pcie_irq_base = 12;
>          mms->virtio_irq_base = 16;
>      }