Re: [Qemu-devel] [PATCH 1/6] xics: add flags for interrupts

[Alexander Graf <agraf@suse.de>]

On 05/07/2014 08:01 AM, Alexey Kardashevskiy wrote:
> The existing interrupt allocation scheme in SPAPR assumes that
> interrupts are allocated at the start time, continously and the config
> will not change. However, there are cases when this is not going to work
> such as:
>
> 1. migration - we will have to have an ability to choose interrupt
> numbers for devices in the command line and this will create gaps in
> interrupt space.
>
> 2. PCI hotplug - interrupts from unplugged device need to be returned
> back to interrupt pool, otherwise we will quickly run out of interrupts.
>
> This replaces a separate lslsi[] array with a byte in the ICSIRQState
> struct and defines "LSI" and "MSI" flags. Neither of these flags set
> signals that the descriptor is not allocated and not in use.
>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
>   hw/intc/xics.c        | 21 ++++++++++++++-------
>   hw/intc/xics_kvm.c    |  5 ++---
>   include/hw/ppc/xics.h |  5 ++++-
>   3 files changed, 20 insertions(+), 11 deletions(-)
>
> diff --git a/hw/intc/xics.c b/hw/intc/xics.c
> index 64aabe7..1f89a00 100644
> --- a/hw/intc/xics.c
> +++ b/hw/intc/xics.c
> @@ -438,7 +438,7 @@ static void ics_set_irq(void *opaque, int srcno, int val)
>   {
>       ICSState *ics = (ICSState *)opaque;
>   
> -    if (ics->islsi[srcno]) {
> +    if (ics->irqs[srcno].flags & XICS_FLAGS_LSI) {
>           set_irq_lsi(ics, srcno, val);
>       } else {
>           set_irq_msi(ics, srcno, val);
> @@ -475,7 +475,7 @@ static void ics_write_xive(ICSState *ics, int nr, int server,
>   
>       trace_xics_ics_write_xive(nr, srcno, server, priority);
>   
> -    if (ics->islsi[srcno]) {
> +    if (ics->irqs[srcno].flags & XICS_FLAGS_LSI) {
>           write_xive_lsi(ics, srcno);
>       } else {
>           write_xive_msi(ics, srcno);
> @@ -497,7 +497,7 @@ static void ics_resend(ICSState *ics)
>   
>       for (i = 0; i < ics->nr_irqs; i++) {
>           /* FIXME: filter by server#? */
> -        if (ics->islsi[i]) {
> +        if (ics->irqs[i].flags & XICS_FLAGS_LSI) {
>               resend_lsi(ics, i);
>           } else {
>               resend_msi(ics, i);
> @@ -512,7 +512,7 @@ static void ics_eoi(ICSState *ics, int nr)
>   
>       trace_xics_ics_eoi(nr);
>   
> -    if (ics->islsi[srcno]) {
> +    if (ics->irqs[srcno].flags & XICS_FLAGS_LSI) {
>           irq->status &= ~XICS_STATUS_SENT;
>       }
>   }
> @@ -609,7 +609,6 @@ static void ics_realize(DeviceState *dev, Error **errp)
>           return;
>       }
>       ics->irqs = g_malloc0(ics->nr_irqs * sizeof(ICSIRQState));
> -    ics->islsi = g_malloc0(ics->nr_irqs * sizeof(bool));
>       ics->qirqs = qemu_allocate_irqs(ics_set_irq, ics, ics->nr_irqs);
>   }
>   
> @@ -646,11 +645,19 @@ qemu_irq xics_get_qirq(XICSState *icp, int irq)
>       return icp->ics->qirqs[irq - icp->ics->offset];
>   }
>   
> +static void ics_set_irq_type(ICSState *ics, int srcno, bool lsi)
> +{
> +    ics->irqs[srcno].flags |=
> +        lsi ? XICS_FLAGS_LSI : XICS_FLAGS_MSI;
> +}
> +
>   void xics_set_irq_type(XICSState *icp, int irq, bool lsi)
>   {
> -    assert(ics_valid_irq(icp->ics, irq));
> +    ICSState *ics = icp->ics;
>   
> -    icp->ics->islsi[irq - icp->ics->offset] = lsi;
> +    assert(ics_valid_irq(ics, irq));
> +
> +    ics_set_irq_type(ics, irq - ics->offset, lsi);

What if this gets called with MSI first, then LSI on the same irq number?

>   }
>   
>   /*
> diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
> index 09476ae..456fc2c 100644
> --- a/hw/intc/xics_kvm.c
> +++ b/hw/intc/xics_kvm.c
> @@ -224,7 +224,7 @@ static int ics_set_kvm_state(ICSState *ics, int version_id)
>               state |= KVM_XICS_MASKED;
>           }
>   
> -        if (ics->islsi[i]) {
> +        if (ics->irqs[i].flags & XICS_FLAGS_LSI) {
>               state |= KVM_XICS_LEVEL_SENSITIVE;
>               if (irq->status & XICS_STATUS_ASSERTED) {
>                   state |= KVM_XICS_PENDING;
> @@ -253,7 +253,7 @@ static void ics_kvm_set_irq(void *opaque, int srcno, int val)
>       int rc;
>   
>       args.irq = srcno + ics->offset;
> -    if (!ics->islsi[srcno]) {
> +    if (ics->irqs[srcno].flags & XICS_FLAGS_MSI) {
>           if (!val) {
>               return;
>           }
> @@ -290,7 +290,6 @@ static void ics_kvm_realize(DeviceState *dev, Error **errp)
>           return;
>       }
>       ics->irqs = g_malloc0(ics->nr_irqs * sizeof(ICSIRQState));
> -    ics->islsi = g_malloc0(ics->nr_irqs * sizeof(bool));
>       ics->qirqs = qemu_allocate_irqs(ics_kvm_set_irq, ics, ics->nr_irqs);
>   }
>   
> diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
> index 0d7673d..aad48cf 100644
> --- a/include/hw/ppc/xics.h
> +++ b/include/hw/ppc/xics.h
> @@ -136,7 +136,6 @@ struct ICSState {
>       uint32_t nr_irqs;
>       uint32_t offset;
>       qemu_irq *qirqs;
> -    bool *islsi;
>       ICSIRQState *irqs;
>       XICSState *icp;
>   };
> @@ -150,6 +149,10 @@ struct ICSIRQState {
>   #define XICS_STATUS_REJECTED           0x4
>   #define XICS_STATUS_MASKED_PENDING     0x8
>       uint8_t status;
> +/* @flags == 0 measn the interrupt is not allocated */
> +#define XICS_FLAGS_LSI                 0x1
> +#define XICS_FLAGS_MSI                 0x2

Please define a mask for the interrupt type.


Alex

> +    uint8_t flags;
>   };
>   
>   qemu_irq xics_get_qirq(XICSState *icp, int irq);