On Friday 08 May 2009 06:22:20 Alex Williamson wrote:
> We're currently using a counter to track the most recent GSI we've
> handed out. This quickly hits KVM_MAX_IRQ_ROUTES when using device
> assignment with a driver that regularly toggles the MSI enable bit.
> This can mean only a few minutes of usable run time. Instead, track
> used GSIs in a bitmap.
>
> Signed-off-by: Alex Williamson <[email protected]>
> ---
>
> Applies on top of "kvm: device-assignment: Catch GSI overflow"
>
> hw/device-assignment.c | 4 ++-
> kvm/libkvm/kvm-common.h | 3 +-
> kvm/libkvm/libkvm.c | 68
> +++++++++++++++++++++++++++++++++++++++++------ kvm/libkvm/libkvm.h |
> 10 +++++++
> 4 files changed, 74 insertions(+), 11 deletions(-)
>
> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
> index e06dd08..5bdae24 100644
> --- a/hw/device-assignment.c
> +++ b/hw/device-assignment.c
> @@ -561,8 +561,10 @@ static void free_dev_irq_entries(AssignedDevice *dev)
> {
> int i;
>
> - for (i = 0; i < dev->irq_entries_nr; i++)
> + for (i = 0; i < dev->irq_entries_nr; i++) {
> kvm_del_routing_entry(kvm_context, &dev->entry[i]);
> + kvm_free_irq_route_gsi(kvm_context, dev->entry[i].gsi);
> + }
> free(dev->entry);
> dev->entry = NULL;
> dev->irq_entries_nr = 0;
> diff --git a/kvm/libkvm/kvm-common.h b/kvm/libkvm/kvm-common.h
> index 591fb53..94f86e5 100644
> --- a/kvm/libkvm/kvm-common.h
> +++ b/kvm/libkvm/kvm-common.h
> @@ -66,8 +66,9 @@ struct kvm_context {
> #ifdef KVM_CAP_IRQ_ROUTING
> struct kvm_irq_routing *irq_routes;
> int nr_allocated_irq_routes;
> + void *used_gsi_bitmap;
> + int max_gsi;
> #endif
> - int max_used_gsi;
> };
>
> int kvm_alloc_kernel_memory(kvm_context_t kvm, unsigned long memory,
> diff --git a/kvm/libkvm/libkvm.c b/kvm/libkvm/libkvm.c
> index 2a4165a..43abc7d 100644
> --- a/kvm/libkvm/libkvm.c
> +++ b/kvm/libkvm/libkvm.c
> @@ -1298,8 +1298,6 @@ int kvm_add_routing_entry(kvm_context_t kvm,
> new->flags = entry->flags;
> new->u = entry->u;
>
> - if (entry->gsi > kvm->max_used_gsi)
> - kvm->max_used_gsi = entry->gsi;
> return 0;
> #else
> return -ENOSYS;
> @@ -1404,20 +1402,72 @@ int kvm_commit_irq_routes(kvm_context_t kvm)
> #endif
> }
>
> +#ifdef KVM_CAP_IRQ_ROUTING
> +static inline void set_bit(unsigned int *buf, int bit)
> +{
> + buf[bit >> 5] |= (1U << (bit & 0x1f));
> +}
> +
> +static inline void clear_bit(unsigned int *buf, int bit)
> +{
> + buf[bit >> 5] &= ~(1U << (bit & 0x1f));
> +}
> +
> +static int kvm_find_free_gsi(kvm_context_t kvm)
> +{
> + int i, bit, gsi;
> + unsigned int *buf = kvm->used_gsi_bitmap;
> +
> + for (i = 0; i < (kvm->max_gsi >> 5); i++) {
> + if (buf[i] != ~0U)
> + break;
> + }
> +
> + if (i == kvm->max_gsi >> 5)
> + return -ENOSPC;
> +
> + bit = ffs(~buf[i]);
> + if (!bit)
> + return -EAGAIN;
> +
> + gsi = (bit - 1) | (i << 5);
> + set_bit(buf, gsi);
> + return gsi;
> +}
> +#endif
> +
> int kvm_get_irq_route_gsi(kvm_context_t kvm)
> {
> #ifdef KVM_CAP_IRQ_ROUTING
> - if (kvm->max_used_gsi >= KVM_IOAPIC_NUM_PINS) {
> - if (kvm->max_used_gsi + 1 < kvm_get_gsi_count(kvm))
> - return kvm->max_used_gsi + 1;
> - else
> - return -ENOSPC;
> - } else
> - return KVM_IOAPIC_NUM_PINS;
> + if (!kvm->max_gsi) {
> + int i;
> +
> + /* Round the number of GSIs supported to a 4 byte
> + * value so we can search it using ints and ffs */
> + i = kvm_get_gsi_count(kvm) & ~0x1f;
> + kvm->used_gsi_bitmap = malloc(i >> 3);
3 or 5?
I am a little confused by these magic numbers, including 0x1f...
I think there are something can indicate the length of unsigned long in
QEmu(sorry, can't find it now...), so how about using ffsl() and get other
constants based on it?
--
regards
Yang, Sheng
> + if (!kvm->used_gsi_bitmap)
> + return -ENOMEM;
> + memset(kvm->used_gsi_bitmap, 0, i >> 3);
> + kvm->max_gsi = i;
> +
> + /* Mark all the IOAPIC pin GSIs as already used */
> + for (i = 0; i <= KVM_IOAPIC_NUM_PINS; i++)
> + set_bit(kvm->used_gsi_bitmap, i);
> + }
> +
> + return kvm_find_free_gsi(kvm);
> #else
> return -ENOSYS;
> #endif
> }
> +
> +void kvm_free_irq_route_gsi(kvm_context_t kvm, int gsi)
> +{
> +#ifdef KVM_CAP_IRQ_ROUTING
> + clear_bit(kvm->used_gsi_bitmap, gsi);
> +#endif
> +}
>
> #ifdef KVM_CAP_DEVICE_MSIX
> int kvm_assign_set_msix_nr(kvm_context_t kvm,
> diff --git a/kvm/libkvm/libkvm.h b/kvm/libkvm/libkvm.h
> index c23d37b..4e9344c 100644
> --- a/kvm/libkvm/libkvm.h
> +++ b/kvm/libkvm/libkvm.h
> @@ -856,6 +856,16 @@ int kvm_commit_irq_routes(kvm_context_t kvm);
> */
> int kvm_get_irq_route_gsi(kvm_context_t kvm);
>
> +/*!
> + * \brief Free used GSI number
> + *
> + * Free used GSI number acquired from kvm_get_irq_route_gsi()
> + *
> + * \param kvm Pointer to the current kvm_context
> + * \param gsi GSI number to free
> + */
> +void kvm_free_irq_route_gsi(kvm_context_t kvm, int gsi);
> +
> #ifdef KVM_CAP_DEVICE_MSIX
> int kvm_assign_set_msix_nr(kvm_context_t kvm,
> struct kvm_assigned_msix_nr *msix_nr);
>
> --
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