diff options
| author | Sean Christopherson <seanjc@google.com> | 2025-05-16 14:35:39 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2025-06-20 13:41:03 -0700 |
| commit | e46ad851150f1dd14b8542b6fb7a51f695a99eb1 (patch) | |
| tree | 2a87fa8efd86535546003a7bb54bd273e59a8098 | |
| parent | ee188dea1677a0d9b3a8097e71b803896b8aaed7 (diff) | |
| download | net-e46ad851150f1dd14b8542b6fb7a51f695a99eb1.tar.gz | |
KVM: Use mask of harvested dirty ring entries to coalesce dirty ring resets
Use "mask" instead of a dedicated boolean to track whether or not there
is at least one to-be-reset entry for the current slot+offset. In the
body of the loop, mask is zero only on the first iteration, i.e. !mask is
equivalent to first_round.
Opportunistically combine the adjacent "if (mask)" statements into a single
if-statement.
No functional change intended.
Cc: Peter Xu <peterx@redhat.com>
Cc: Yan Zhao <yan.y.zhao@intel.com>
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Reviewed-by: James Houghton <jthoughton@google.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20250516213540.2546077-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | virt/kvm/dirty_ring.c | 64 |
1 files changed, 31 insertions, 33 deletions
diff --git a/virt/kvm/dirty_ring.c b/virt/kvm/dirty_ring.c index 939198ac669542..4caa63e610d261 100644 --- a/virt/kvm/dirty_ring.c +++ b/virt/kvm/dirty_ring.c @@ -121,7 +121,6 @@ int kvm_dirty_ring_reset(struct kvm *kvm, struct kvm_dirty_ring *ring, u64 cur_offset, next_offset; unsigned long mask = 0; struct kvm_dirty_gfn *entry; - bool first_round = true; while (likely((*nr_entries_reset) < INT_MAX)) { if (signal_pending(current)) @@ -141,42 +140,42 @@ int kvm_dirty_ring_reset(struct kvm *kvm, struct kvm_dirty_ring *ring, ring->reset_index++; (*nr_entries_reset)++; - /* - * While the size of each ring is fixed, it's possible for the - * ring to be constantly re-dirtied/harvested while the reset - * is in-progress (the hard limit exists only to guard against - * wrapping the count into negative space). - */ - if (!first_round) + if (mask) { + /* + * While the size of each ring is fixed, it's possible + * for the ring to be constantly re-dirtied/harvested + * while the reset is in-progress (the hard limit exists + * only to guard against the count becoming negative). + */ cond_resched(); - /* - * Try to coalesce the reset operations when the guest is - * scanning pages in the same slot. - */ - if (!first_round && next_slot == cur_slot) { - s64 delta = next_offset - cur_offset; - - if (delta >= 0 && delta < BITS_PER_LONG) { - mask |= 1ull << delta; - continue; + /* + * Try to coalesce the reset operations when the guest + * is scanning pages in the same slot. + */ + if (next_slot == cur_slot) { + s64 delta = next_offset - cur_offset; + + if (delta >= 0 && delta < BITS_PER_LONG) { + mask |= 1ull << delta; + continue; + } + + /* Backwards visit, careful about overflows! */ + if (delta > -BITS_PER_LONG && delta < 0 && + (mask << -delta >> -delta) == mask) { + cur_offset = next_offset; + mask = (mask << -delta) | 1; + continue; + } } - /* Backwards visit, careful about overflows! */ - if (delta > -BITS_PER_LONG && delta < 0 && - (mask << -delta >> -delta) == mask) { - cur_offset = next_offset; - mask = (mask << -delta) | 1; - continue; - } - } - - /* - * Reset the slot for all the harvested entries that have been - * gathered, but not yet fully processed. - */ - if (mask) + /* + * Reset the slot for all the harvested entries that + * have been gathered, but not yet fully processed. + */ kvm_reset_dirty_gfn(kvm, cur_slot, cur_offset, mask); + } /* * The current slot was reset or this is the first harvested @@ -185,7 +184,6 @@ int kvm_dirty_ring_reset(struct kvm *kvm, struct kvm_dirty_ring *ring, cur_slot = next_slot; cur_offset = next_offset; mask = 1; - first_round = false; } /* |