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| author | Paolo Bonzini | 2022-08-26 13:00:00 +0200 |
|---|---|---|
| committer | Paolo Bonzini | 2022-09-01 08:37:04 +0200 |
| commit | 4802bf910eee98312c4a9777ac2567e6a0445c46 (patch) | |
| tree | 7c1d4d078912c9f41362d4109504ead108066298 /accel | |
| parent | meson: remove dead assignments (diff) | |
| download | qemu-4802bf910eee98312c4a9777ac2567e6a0445c46.tar.gz qemu-4802bf910eee98312c4a9777ac2567e6a0445c46.tar.xz qemu-4802bf910eee98312c4a9777ac2567e6a0445c46.zip | |
KVM: dirty ring: add missing memory barrier
The KVM_DIRTY_GFN_F_DIRTY flag ensures that the entry is valid. If
the read of the fields are not ordered after the read of the flag,
QEMU might see stale values.
Cc: Gavin Shan <gshan@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'accel')
| -rw-r--r-- | accel/kvm/kvm-all.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index 8d81ab74de..136c8eaed3 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -719,7 +719,11 @@ static void kvm_dirty_ring_mark_page(KVMState *s, uint32_t as_id, static bool dirty_gfn_is_dirtied(struct kvm_dirty_gfn *gfn) { - return gfn->flags == KVM_DIRTY_GFN_F_DIRTY; + /* + * Read the flags before the value. Pairs with barrier in + * KVM's kvm_dirty_ring_push() function. + */ + return qatomic_load_acquire(&gfn->flags) == KVM_DIRTY_GFN_F_DIRTY; } static void dirty_gfn_set_collected(struct kvm_dirty_gfn *gfn) |