summaryrefslogtreecommitdiffstats
path: root/virt/kvm/dirty_ring.c
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /virt/kvm/dirty_ring.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'virt/kvm/dirty_ring.c')
-rw-r--r--virt/kvm/dirty_ring.c180
1 files changed, 180 insertions, 0 deletions
diff --git a/virt/kvm/dirty_ring.c b/virt/kvm/dirty_ring.c
new file mode 100644
index 000000000..d6fabf238
--- /dev/null
+++ b/virt/kvm/dirty_ring.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * KVM dirty ring implementation
+ *
+ * Copyright 2019 Red Hat, Inc.
+ */
+#include <linux/kvm_host.h>
+#include <linux/kvm.h>
+#include <linux/vmalloc.h>
+#include <linux/kvm_dirty_ring.h>
+#include <trace/events/kvm.h>
+#include "kvm_mm.h"
+
+int __weak kvm_cpu_dirty_log_size(void)
+{
+ return 0;
+}
+
+u32 kvm_dirty_ring_get_rsvd_entries(void)
+{
+ return KVM_DIRTY_RING_RSVD_ENTRIES + kvm_cpu_dirty_log_size();
+}
+
+static u32 kvm_dirty_ring_used(struct kvm_dirty_ring *ring)
+{
+ return READ_ONCE(ring->dirty_index) - READ_ONCE(ring->reset_index);
+}
+
+bool kvm_dirty_ring_soft_full(struct kvm_dirty_ring *ring)
+{
+ return kvm_dirty_ring_used(ring) >= ring->soft_limit;
+}
+
+static bool kvm_dirty_ring_full(struct kvm_dirty_ring *ring)
+{
+ return kvm_dirty_ring_used(ring) >= ring->size;
+}
+
+static void kvm_reset_dirty_gfn(struct kvm *kvm, u32 slot, u64 offset, u64 mask)
+{
+ struct kvm_memory_slot *memslot;
+ int as_id, id;
+
+ as_id = slot >> 16;
+ id = (u16)slot;
+
+ if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
+ return;
+
+ memslot = id_to_memslot(__kvm_memslots(kvm, as_id), id);
+
+ if (!memslot || (offset + __fls(mask)) >= memslot->npages)
+ return;
+
+ KVM_MMU_LOCK(kvm);
+ kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, offset, mask);
+ KVM_MMU_UNLOCK(kvm);
+}
+
+int kvm_dirty_ring_alloc(struct kvm_dirty_ring *ring, int index, u32 size)
+{
+ ring->dirty_gfns = vzalloc(size);
+ if (!ring->dirty_gfns)
+ return -ENOMEM;
+
+ ring->size = size / sizeof(struct kvm_dirty_gfn);
+ ring->soft_limit = ring->size - kvm_dirty_ring_get_rsvd_entries();
+ ring->dirty_index = 0;
+ ring->reset_index = 0;
+ ring->index = index;
+
+ return 0;
+}
+
+static inline void kvm_dirty_gfn_set_invalid(struct kvm_dirty_gfn *gfn)
+{
+ smp_store_release(&gfn->flags, 0);
+}
+
+static inline void kvm_dirty_gfn_set_dirtied(struct kvm_dirty_gfn *gfn)
+{
+ gfn->flags = KVM_DIRTY_GFN_F_DIRTY;
+}
+
+static inline bool kvm_dirty_gfn_harvested(struct kvm_dirty_gfn *gfn)
+{
+ return smp_load_acquire(&gfn->flags) & KVM_DIRTY_GFN_F_RESET;
+}
+
+int kvm_dirty_ring_reset(struct kvm *kvm, struct kvm_dirty_ring *ring)
+{
+ u32 cur_slot, next_slot;
+ u64 cur_offset, next_offset;
+ unsigned long mask;
+ int count = 0;
+ struct kvm_dirty_gfn *entry;
+ bool first_round = true;
+
+ /* This is only needed to make compilers happy */
+ cur_slot = cur_offset = mask = 0;
+
+ while (true) {
+ entry = &ring->dirty_gfns[ring->reset_index & (ring->size - 1)];
+
+ if (!kvm_dirty_gfn_harvested(entry))
+ break;
+
+ next_slot = READ_ONCE(entry->slot);
+ next_offset = READ_ONCE(entry->offset);
+
+ /* Update the flags to reflect that this GFN is reset */
+ kvm_dirty_gfn_set_invalid(entry);
+
+ ring->reset_index++;
+ count++;
+ /*
+ * 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;
+ }
+
+ /* 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;
+ }
+ }
+ kvm_reset_dirty_gfn(kvm, cur_slot, cur_offset, mask);
+ cur_slot = next_slot;
+ cur_offset = next_offset;
+ mask = 1;
+ first_round = false;
+ }
+
+ kvm_reset_dirty_gfn(kvm, cur_slot, cur_offset, mask);
+
+ trace_kvm_dirty_ring_reset(ring);
+
+ return count;
+}
+
+void kvm_dirty_ring_push(struct kvm_dirty_ring *ring, u32 slot, u64 offset)
+{
+ struct kvm_dirty_gfn *entry;
+
+ /* It should never get full */
+ WARN_ON_ONCE(kvm_dirty_ring_full(ring));
+
+ entry = &ring->dirty_gfns[ring->dirty_index & (ring->size - 1)];
+
+ entry->slot = slot;
+ entry->offset = offset;
+ /*
+ * Make sure the data is filled in before we publish this to
+ * the userspace program. There's no paired kernel-side reader.
+ */
+ smp_wmb();
+ kvm_dirty_gfn_set_dirtied(entry);
+ ring->dirty_index++;
+ trace_kvm_dirty_ring_push(ring, slot, offset);
+}
+
+struct page *kvm_dirty_ring_get_page(struct kvm_dirty_ring *ring, u32 offset)
+{
+ return vmalloc_to_page((void *)ring->dirty_gfns + offset * PAGE_SIZE);
+}
+
+void kvm_dirty_ring_free(struct kvm_dirty_ring *ring)
+{
+ vfree(ring->dirty_gfns);
+ ring->dirty_gfns = NULL;
+}