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[PATCH RFC v2 4/9] KVM: Create the KVMSlot dirty bitmap on flag changes
From: |
Peter Xu |
Subject: |
[PATCH RFC v2 4/9] KVM: Create the KVMSlot dirty bitmap on flag changes |
Date: |
Tue, 28 Apr 2020 16:05:04 -0400 |
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 <address@hidden>
Signed-off-by: Peter Xu <address@hidden>
---
accel/kvm/kvm-all.c | 23 +++++++++--------------
1 file changed, 9 insertions(+), 14 deletions(-)
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 1f1fd5316e..dc6371b8b2 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -162,6 +162,8 @@ static NotifierList kvm_irqchip_change_notifiers =
#define kvm_slots_lock(kml) qemu_mutex_lock(&(kml)->slots_lock)
#define kvm_slots_unlock(kml) qemu_mutex_unlock(&(kml)->slots_lock)
+static void kvm_slot_init_dirty_bitmap(KVMSlot *mem);
+
int kvm_get_max_memslots(void)
{
KVMState *s = KVM_STATE(current_accel());
@@ -452,6 +454,7 @@ 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);
}
@@ -536,8 +539,12 @@ 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
@@ -588,11 +595,6 @@ 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);
if (kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d) == -1) {
@@ -1086,14 +1088,7 @@ 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__,
--
2.24.1
- [PATCH RFC v2 0/9] KVM: Dirty ring support (QEMU part), Peter Xu, 2020/04/28
- [PATCH RFC v2 1/9] KVM: Fixup kvm_log_clear_one_slot() ioctl return check, Peter Xu, 2020/04/28
- [PATCH RFC v2 2/9] linux-headers: Update, Peter Xu, 2020/04/28
- [PATCH RFC v2 3/9] memory: Introduce log_sync_global() to memory listener, Peter Xu, 2020/04/28
- [PATCH RFC v2 4/9] KVM: Create the KVMSlot dirty bitmap on flag changes,
Peter Xu <=
- [PATCH RFC v2 5/9] KVM: Provide helper to get kvm dirty log, Peter Xu, 2020/04/28
- [PATCH RFC v2 6/9] KVM: Provide helper to sync dirty bitmap from slot to ramblock, Peter Xu, 2020/04/28
- [PATCH RFC v2 8/9] KVM: Add dirty-gfn-count property, Peter Xu, 2020/04/28
- [PATCH RFC v2 7/9] KVM: Cache kvm slot dirty bitmap size, Peter Xu, 2020/04/28
- [PATCH RFC v2 9/9] KVM: Dirty ring support, Peter Xu, 2020/04/28