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"
v4: Fix gsi_bytes calculation noted by Sheng Yang
hw/device-assignment.c | 4 ++
kvm/libkvm/kvm-common.h | 4 ++
kvm/libkvm/libkvm.c | 81 +++++++++++++++++++++++++++++++++++++++++------
kvm/libkvm/libkvm.h | 10 ++++++
4 files changed, 86 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..3eaa120 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 +328,25 @@ 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) * 4;
+ kvm->used_gsi_bitmap = malloc(gsi_bytes);
+ if (!kvm->used_gsi_bitmap)
+ goto out_close;
+ memset(kvm->used_gsi_bitmap, 0, gsi_bytes);
+ kvm->max_gsi = gsi_bytes * 8;
+
+ /* 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 +1323,6 @@ 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 +1427,54 @@ 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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