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KVM: Create the KVMSlot dirty bitmap on flag changes

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Previously we have two places that will create the per KVMSlot dirty
bitmap:

  1. When a newly created KVMSlot has dirty logging enabled,
  2. When the first log_sync() happens for a memory slot.

The 2nd case is lazy-init, while the 1st case is not (which is a fix
of what the 2nd case missed).

To do explicit initialization of dirty bitmaps, what we're missing is
to create the dirty bitmap when the slot changed from not-dirty-track
to dirty-track.  Do that in kvm_slot_update_flags().

With that, we can safely remove the 2nd lazy-init.

This change will be needed for kvm dirty ring because kvm dirty ring
does not use the log_sync() interface at all.

Also move all the pre-checks into kvm_slot_init_dirty_bitmap().

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20210506160549.130416-4-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Peter Xu 2021-05-06 12:05:42 -04:00 committed by Paolo Bonzini
parent a2f77862ff
commit ea776d15ad
1 changed files with 9 additions and 14 deletions
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23
accel/kvm/kvm-all.c
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@ -177,6 +177,8 @@ static QemuMutex kml_slots_lock;
#define kvm_slots_lock() qemu_mutex_lock(&kml_slots_lock)
#define kvm_slots_unlock() qemu_mutex_unlock(&kml_slots_lock)
static void kvm_slot_init_dirty_bitmap(KVMSlot *mem);
static inline void kvm_resample_fd_remove(int gsi)
{
KVMResampleFd *rfd;
@ -500,6 +502,7 @@ static int kvm_slot_update_flags(KVMMemoryListener *kml, KVMSlot *mem,
return 0;
}
kvm_slot_init_dirty_bitmap(mem);
return kvm_set_user_memory_region(kml, mem, false);
}
@ -584,8 +587,12 @@ static int kvm_get_dirty_pages_log_range(MemoryRegionSection *section,
#define ALIGN(x, y) (((x)+(y)-1) & ~((y)-1))
/* Allocate the dirty bitmap for a slot */
static void kvm_memslot_init_dirty_bitmap(KVMSlot *mem)
static void kvm_slot_init_dirty_bitmap(KVMSlot *mem)
{
if (!(mem->flags & KVM_MEM_LOG_DIRTY_PAGES) || mem->dirty_bmap) {
return;
}
/*
* XXX bad kernel interface alert
* For dirty bitmap, kernel allocates array of size aligned to
@ -640,11 +647,6 @@ static int kvm_physical_sync_dirty_bitmap(KVMMemoryListener *kml,
goto out;
}
if (!mem->dirty_bmap) {
/* Allocate on the first log_sync, once and for all */
kvm_memslot_init_dirty_bitmap(mem);
}
d.dirty_bitmap = mem->dirty_bmap;
d.slot = mem->slot | (kml->as_id << 16);
ret = kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d);
@ -1181,14 +1183,7 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml,
mem->start_addr = start_addr;
mem->ram = ram;
mem->flags = kvm_mem_flags(mr);
if (mem->flags & KVM_MEM_LOG_DIRTY_PAGES) {
/*
* Reallocate the bmap; it means it doesn't disappear in
* middle of a migrate.
*/
kvm_memslot_init_dirty_bitmap(mem);
}
kvm_slot_init_dirty_bitmap(mem);
err = kvm_set_user_memory_region(kml, mem, true);
if (err) {
fprintf(stderr, "%s: error registering slot: %s\n", __func__,