From: Alex Williamson <[email protected]> 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 (such as Linux kernels 2.6.21-26). 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]> Signed-off-by: Avi Kivity <[email protected]> diff --git a/kvm/libkvm/kvm-common.h b/kvm/libkvm/kvm-common.h index 591fb53..c95c591 100644 --- a/kvm/libkvm/kvm-common.h +++ b/kvm/libkvm/kvm-common.h @@ -67,7 +67,8 @@ struct kvm_context { struct kvm_irq_routing *irq_routes; int nr_allocated_irq_routes; #endif - int max_used_gsi; + void *used_gsi_bitmap; + int max_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..c5d6a7f 100644 --- a/kvm/libkvm/libkvm.c +++ b/kvm/libkvm/libkvm.c @@ -61,10 +61,32 @@ #define DPRINTF(fmt, args...) do {} while (0) #endif +#define MIN(x,y) ((x) < (y) ? (x) : (y)) +#define ALIGN(x, y) (((x)+(y)-1) & ~((y)-1)) int kvm_abi = EXPECTED_KVM_API_VERSION; int kvm_page_size; +static inline void set_gsi(kvm_context_t kvm, unsigned int gsi) +{ + uint32_t *bitmap = kvm->used_gsi_bitmap; + + if (gsi < kvm->max_gsi) + bitmap[gsi / 32] |= 1U << (gsi % 32); + else + DPRINTF("Invalid GSI %d\n"); +} + +static inline void clear_gsi(kvm_context_t kvm, unsigned int gsi) +{ + uint32_t *bitmap = kvm->used_gsi_bitmap; + + if (gsi < kvm->max_gsi) + bitmap[gsi / 32] &= ~(1U << (gsi % 32)); + else + DPRINTF("Invalid GSI %d\n"); +} + struct slot_info { unsigned long phys_addr; unsigned long len; @@ -285,7 +307,7 @@ kvm_context_t kvm_init(struct kvm_callbacks *callbacks, { int fd; kvm_context_t kvm; - int r; + int r, gsi_count; fd = open("/dev/kvm", O_RDWR); if (fd == -1) { @@ -323,6 +345,23 @@ kvm_context_t kvm_init(struct kvm_callbacks *callbacks, kvm->no_irqchip_creation = 0; kvm->no_pit_creation = 0; + gsi_count = kvm_get_gsi_count(kvm); + if (gsi_count > 0) { + int gsi_bits, i; + + /* Round up so we can search ints using ffs */ + gsi_bits = ALIGN(gsi_count, 32); + kvm->used_gsi_bitmap = malloc(gsi_bits / 8); + if (!kvm->used_gsi_bitmap) + goto out_close; + memset(kvm->used_gsi_bitmap, 0, gsi_bits / 8); + kvm->max_gsi = gsi_bits; + + /* Mark any over-allocated bits as already in use */ + for (i = gsi_count; i < gsi_bits; i++) + set_gsi(kvm, i); + } + return kvm; out_close: close(fd); @@ -626,9 +665,6 @@ int kvm_get_dirty_pages(kvm_context_t kvm, unsigned long phys_addr, void *buf) return kvm_get_map(kvm, KVM_GET_DIRTY_LOG, slot, buf); } -#define ALIGN(x, y) (((x)+(y)-1) & ~((y)-1)) -#define BITMAP_SIZE(m) (ALIGN(((m)/PAGE_SIZE), sizeof(long) * 8) / 8) - int kvm_get_dirty_pages_range(kvm_context_t kvm, unsigned long phys_addr, unsigned long len, void *buf, void *opaque, int (*cb)(unsigned long start, unsigned long len, @@ -1298,8 +1334,8 @@ 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; + set_gsi(kvm, entry->gsi); + return 0; #else return -ENOSYS; @@ -1327,12 +1363,14 @@ int kvm_del_routing_entry(kvm_context_t kvm, { #ifdef KVM_CAP_IRQ_ROUTING struct kvm_irq_routing_entry *e, *p; - int i, found = 0; + int i, gsi, found = 0; + + gsi = entry->gsi; for (i = 0; i < kvm->irq_routes->nr; ++i) { e = &kvm->irq_routes->entries[i]; if (e->type == entry->type - && e->gsi == entry->gsi) { + && e->gsi == gsi) { switch (e->type) { case KVM_IRQ_ROUTING_IRQCHIP: { @@ -1363,8 +1401,19 @@ int kvm_del_routing_entry(kvm_context_t kvm, default: break; } - if (found) + if (found) { + /* If there are no other users of this GSI + * mark it available in the bitmap */ + for (i = 0; i < kvm->irq_routes->nr; i++) { + e = &kvm->irq_routes->entries[i]; + if (e->gsi == gsi) + break; + } + if (i == kvm->irq_routes->nr) + clear_gsi(kvm, gsi); + return 0; + } } } return -ESRCH; @@ -1406,17 +1455,19 @@ int kvm_commit_irq_routes(kvm_context_t kvm) 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 <= kvm_get_gsi_count(kvm)) - return kvm->max_used_gsi + 1; - else - return -ENOSPC; - } else - return KVM_IOAPIC_NUM_PINS; -#else - return -ENOSYS; -#endif + int i, bit; + uint32_t *buf = kvm->used_gsi_bitmap; + + /* Return the lowest unused GSI in the bitmap */ + for (i = 0; i < kvm->max_gsi / 32; i++) { + bit = ffs(~buf[i]); + if (!bit) + continue; + + return bit - 1 + i * 32; + } + + return -ENOSPC; } #ifdef KVM_CAP_DEVICE_MSIX -- To unsubscribe from this list: send the line "unsubscribe kvm-commits" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
