On Wednesday 13 May 2009 06:07:15 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 <alex.williamson@xxxxxx>
> ---
>
> v2: Added mutex to protect gsi bitmap
> v3: Updated for comments from Michael Tsirkin
> No longer depends on "[PATCH] kvm: device-assignment: Catch GSI
> overflow"
>
> hw/device-assignment.c | 4 ++
> kvm/libkvm/kvm-common.h | 4 ++
> kvm/libkvm/libkvm.c | 83
> +++++++++++++++++++++++++++++++++++++++++------ kvm/libkvm/libkvm.h |
> 10 ++++++
> 4 files changed, 88 insertions(+), 13 deletions(-)
>
> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
> index a7365c8..a6cc9b9 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..4b3cb51 100644
> --- a/kvm/libkvm/kvm-common.h
> +++ b/kvm/libkvm/kvm-common.h
> @@ -66,8 +66,10 @@ 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;
> + pthread_mutex_t gsi_mutex;
> #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 ba0a5d1..3d7ab75 100644
> --- a/kvm/libkvm/libkvm.c
> +++ b/kvm/libkvm/libkvm.c
> @@ -35,6 +35,7 @@
> #include <errno.h>
> #include <sys/ioctl.h>
> #include <inttypes.h>
> +#include <pthread.h>
> #include "libkvm.h"
>
> #if defined(__x86_64__) || defined(__i386__)
> @@ -65,6 +66,8 @@
> int kvm_abi = EXPECTED_KVM_API_VERSION;
> int kvm_page_size;
>
> +static inline void set_bit(uint32_t *buf, unsigned int bit);
> +
> struct slot_info {
> unsigned long phys_addr;
> unsigned long len;
> @@ -286,6 +289,9 @@ kvm_context_t kvm_init(struct kvm_callbacks *callbacks,
> int fd;
> kvm_context_t kvm;
> int r;
> +#ifdef KVM_CAP_IRQ_ROUTING
> + int gsi_count, gsi_bytes, i;
> +#endif
>
> fd = open("/dev/kvm", O_RDWR);
> if (fd == -1) {
> @@ -322,6 +328,27 @@ kvm_context_t kvm_init(struct kvm_callbacks
> *callbacks, kvm->dirty_pages_log_all = 0;
> kvm->no_irqchip_creation = 0;
> kvm->no_pit_creation = 0;
> +#ifdef KVM_CAP_IRQ_ROUTING
> + pthread_mutex_init(&kvm->gsi_mutex, NULL);
> +
> + gsi_count = kvm_get_gsi_count(kvm);
> + /* Round up so we can search ints using ffs */
> + gsi_bytes = (gsi_count + 31) / 32;
CMIW, should it be gsi_bytes = (gsi_count + 7) / 8? This looks like bits-to-
int.
> + kvm->used_gsi_bitmap = malloc(gsi_bytes);
> + if (!kvm->used_gsi_bitmap) {
> + pthread_mutex_unlock(&kvm->gsi_mutex);
> + goto out_close;
> + }
> + memset(kvm->used_gsi_bitmap, 0, gsi_bytes);
> + kvm->max_gsi = gsi_bytes * 8;
So max_gsi = gsi_count / 4?
--
regards
Yang, Sheng
> +
> + /* Mark all the IOAPIC pin GSIs and any over-allocated
> + * GSIs as already in use. */
> + for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++)
> + set_bit(kvm->used_gsi_bitmap, i);
> + for (i = gsi_count; i < kvm->max_gsi; i++)
> + set_bit(kvm->used_gsi_bitmap, i);
> +#endif
>
> return kvm;
> out_close:
> @@ -1298,8 +1325,6 @@ 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;
> @@ -1404,18 +1429,54 @@ int kvm_commit_irq_routes(kvm_context_t kvm)
> #endif
> }
>
> +#ifdef KVM_CAP_IRQ_ROUTING
> +static inline void set_bit(uint32_t *buf, unsigned int bit)
> +{
> + buf[bit / 32] |= 1U << (bit % 32);
> +}
> +
> +static inline void clear_bit(uint32_t *buf, unsigned int bit)
> +{
> + buf[bit / 32] &= ~(1U << (bit % 32));
> +}
> +
> +static int kvm_find_free_gsi(kvm_context_t kvm)
> +{
> + int i, bit, gsi;
> + uint32_t *buf = kvm->used_gsi_bitmap;
> +
> + for (i = 0; i < kvm->max_gsi / 32; i++) {
> + bit = ffs(~buf[i]);
> + if (!bit)
> + continue;
> +
> + gsi = bit - 1 + i * 32;
> + set_bit(buf, gsi);
> + return gsi;
> + }
> +
> + return -ENOSPC;
> +}
> +#endif
> +
> int kvm_get_irq_route_gsi(kvm_context_t kvm)
> {
> + int gsi = -ENOSYS;
> +
> #ifdef KVM_CAP_IRQ_ROUTING
> - if (kvm->max_used_gsi >= KVM_IOAPIC_NUM_PINS) {
> - if (kvm->max_used_gsi <= kvm_get_gsi_count(kvm))
> - return kvm->max_used_gsi + 1;
> - else
> - return -ENOSPC;
> - } else
> - return KVM_IOAPIC_NUM_PINS;
> -#else
> - return -ENOSYS;
> + pthread_mutex_lock(&kvm->gsi_mutex);
> + gsi = kvm_find_free_gsi(kvm);
> + pthread_mutex_unlock(&kvm->gsi_mutex);
> +#endif
> + return gsi;
> +}
> +
> +void kvm_free_irq_route_gsi(kvm_context_t kvm, int gsi)
> +{
> +#ifdef KVM_CAP_IRQ_ROUTING
> + pthread_mutex_lock(&kvm->gsi_mutex);
> + clear_bit(kvm->used_gsi_bitmap, gsi);
> + pthread_mutex_unlock(&kvm->gsi_mutex);
> #endif
> }
>
> diff --git a/kvm/libkvm/libkvm.h b/kvm/libkvm/libkvm.h
> index 4821a1e..845bb8a 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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