QEMU-Devel Archive on lore.kernel.org
 help / color / Atom feed
From: Peter Xu <peterx@redhat.com>
To: qemu-devel@nongnu.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
	peterx@redhat.com
Subject: [PATCH RFC v3 05/11] KVM: Create the KVMSlot dirty bitmap on flag changes
Date: Sat, 23 May 2020 19:20:29 -0400
Message-ID: <20200523232035.1029349-6-peterx@redhat.com> (raw)
In-Reply-To: <20200523232035.1029349-1-peterx@redhat.com>

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>
---
 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 6bdb7909cc..5b626af2a7 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -165,6 +165,8 @@ 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);
+
 int kvm_get_max_memslots(void)
 {
     KVMState *s = KVM_STATE(current_accel());
@@ -455,6 +457,7 @@ 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);
 }
 
@@ -539,8 +542,12 @@ 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
@@ -591,11 +598,6 @@ 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) {
@@ -1125,14 +1127,7 @@ 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__,
-- 
2.26.2



  parent reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-23 23:20 [PATCH RFC v3 00/11] KVM: Dirty ring support (QEMU part) Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 01/11] linux-headers: Update Peter Xu
2020-05-24 13:27   ` Peter Maydell
2020-05-24 14:06     ` Peter Xu
2020-05-24 17:50       ` Peter Maydell
2020-05-25 14:29         ` Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 02/11] memory: Introduce log_sync_global() to memory listener Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 03/11] KVM: Fixup kvm_log_clear_one_slot() ioctl return check Peter Xu
2020-05-24 16:39   ` Philippe Mathieu-Daudé
2020-05-23 23:20 ` [PATCH RFC v3 04/11] KVM: Use a big lock to replace per-kml slots_lock Peter Xu
2020-05-23 23:20 ` Peter Xu [this message]
2020-05-23 23:20 ` [PATCH RFC v3 06/11] KVM: Provide helper to get kvm dirty log Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 07/11] KVM: Provide helper to sync dirty bitmap from slot to ramblock Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 08/11] KVM: Simplify dirty log sync in kvm_set_phys_mem Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 09/11] KVM: Cache kvm slot dirty bitmap size Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 10/11] KVM: Add dirty-gfn-count property Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 11/11] KVM: Dirty ring support Peter Xu
2020-05-24 13:06 ` [PATCH RFC v3 00/11] KVM: Dirty ring support (QEMU part) Peter Xu
2020-05-26 14:17 ` Peter Xu

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200523232035.1029349-6-peterx@redhat.com \
    --to=peterx@redhat.com \
    --cc=dgilbert@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=qemu-devel@nongnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

QEMU-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/qemu-devel/0 qemu-devel/git/0.git
	git clone --mirror https://lore.kernel.org/qemu-devel/1 qemu-devel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 qemu-devel qemu-devel/ https://lore.kernel.org/qemu-devel \
		qemu-devel@nongnu.org
	public-inbox-index qemu-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.nongnu.qemu-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git