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Re: [Qemu-devel] [PATCH] kvm/irqchip: use bitmap utility for gsi trackin
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] kvm/irqchip: use bitmap utility for gsi tracking |
Date: |
Mon, 7 Mar 2016 10:47:53 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 |
On 06/03/2016 02:57, Wei Yang wrote:
> By using utilities in bitops and bitmap, this patch tries to make it more
> friendly to audience. No functional change.
>
> Signed-off-by: Wei Yang <address@hidden>
> ---
> kvm-all.c | 34 ++++++++++------------------------
> 1 file changed, 10 insertions(+), 24 deletions(-)
>
> diff --git a/kvm-all.c b/kvm-all.c
> index bd9e764..ed3f4a2 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -90,7 +90,7 @@ struct KVMState
> #ifdef KVM_CAP_IRQ_ROUTING
> struct kvm_irq_routing *irq_routes;
> int nr_allocated_irq_routes;
> - uint32_t *used_gsi_bitmap;
> + unsigned long *used_gsi_bitmap;
> unsigned int gsi_count;
> QTAILQ_HEAD(msi_hashtab, KVMMSIRoute) msi_hashtab[KVM_MSI_HASHTAB_SIZE];
> #endif
> @@ -951,12 +951,12 @@ typedef struct KVMMSIRoute {
>
> static void set_gsi(KVMState *s, unsigned int gsi)
> {
> - s->used_gsi_bitmap[gsi / 32] |= 1U << (gsi % 32);
> + set_bit(gsi, s->used_gsi_bitmap);
> }
>
> static void clear_gsi(KVMState *s, unsigned int gsi)
> {
> - s->used_gsi_bitmap[gsi / 32] &= ~(1U << (gsi % 32));
> + clear_bit(gsi, s->used_gsi_bitmap);
> }
>
> void kvm_init_irq_routing(KVMState *s)
> @@ -965,17 +965,9 @@ void kvm_init_irq_routing(KVMState *s)
>
> gsi_count = kvm_check_extension(s, KVM_CAP_IRQ_ROUTING) - 1;
> if (gsi_count > 0) {
> - unsigned int gsi_bits, i;
> -
> /* Round up so we can search ints using ffs */
> - gsi_bits = ALIGN(gsi_count, 32);
> - s->used_gsi_bitmap = g_malloc0(gsi_bits / 8);
> + s->used_gsi_bitmap = bitmap_new(gsi_count);
> s->gsi_count = gsi_count;
> -
> - /* Mark any over-allocated bits as already in use */
> - for (i = gsi_count; i < gsi_bits; i++) {
> - set_gsi(s, i);
> - }
> }
>
> s->irq_routes = g_malloc0(sizeof(*s->irq_routes));
> @@ -1105,9 +1097,7 @@ static void kvm_flush_dynamic_msi_routes(KVMState *s)
>
> static int kvm_irqchip_get_virq(KVMState *s)
> {
> - uint32_t *word = s->used_gsi_bitmap;
> - int max_words = ALIGN(s->gsi_count, 32) / 32;
> - int i, zeroes;
> + int next_virq;
>
> /*
> * PIC and IOAPIC share the first 16 GSI numbers, thus the available
> @@ -1120,16 +1110,12 @@ static int kvm_irqchip_get_virq(KVMState *s)
> }
>
> /* Return the lowest unused GSI in the bitmap */
> - for (i = 0; i < max_words; i++) {
> - zeroes = ctz32(~word[i]);
> - if (zeroes == 32) {
> - continue;
> - }
> -
> - return zeroes + i * 32;
> + next_virq = find_first_zero_bit(s->used_gsi_bitmap, s->gsi_count);
> + if (next_virq >= s->gsi_count) {
> + return -ENOSPC;
> + } else {
> + return next_virq;
> }
> - return -ENOSPC;
> -
> }
>
> static KVMMSIRoute *kvm_lookup_msi_route(KVMState *s, MSIMessage msg)
>
Queued, thanks. I will send a pull request today.
Paolo