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accel/kvm: refactor dirty ring setup

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Refactor setting up of dirty ring code in kvm_init() so that is can be
reused in the future patchsets.

Signed-off-by: Ani Sinha <anisinha@redhat.com>
Link: https://lore.kernel.org/r/20240912061838.4501-1-anisinha@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Ani Sinha 2024-09-12 11:48:38 +05:30 committed by Paolo Bonzini
parent f9423e9f0a
commit 28ed7f9761
1 changed files with 50 additions and 38 deletions
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88
accel/kvm/kvm-all.c
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@ -2435,6 +2435,55 @@ static int find_kvm_machine_type(MachineState *ms)
return type;
}
static int kvm_setup_dirty_ring(KVMState *s)
{
uint64_t dirty_log_manual_caps;
int ret;
/*
* Enable KVM dirty ring if supported, otherwise fall back to
* dirty logging mode
*/
ret = kvm_dirty_ring_init(s);
if (ret < 0) {
return ret;
}
/*
* KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is not needed when dirty ring is
* enabled. More importantly, KVM_DIRTY_LOG_INITIALLY_SET will assume no
* page is wr-protected initially, which is against how kvm dirty ring is
* usage - kvm dirty ring requires all pages are wr-protected at the very
* beginning. Enabling this feature for dirty ring causes data corruption.
*
* TODO: Without KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 and kvm clear dirty log,
* we may expect a higher stall time when starting the migration. In the
* future we can enable KVM_CLEAR_DIRTY_LOG to work with dirty ring too:
* instead of clearing dirty bit, it can be a way to explicitly wr-protect
* guest pages.
*/
if (!s->kvm_dirty_ring_size) {
dirty_log_manual_caps =
kvm_check_extension(s, KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2);
dirty_log_manual_caps &= (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE |
KVM_DIRTY_LOG_INITIALLY_SET);
s->manual_dirty_log_protect = dirty_log_manual_caps;
if (dirty_log_manual_caps) {
ret = kvm_vm_enable_cap(s, KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2, 0,
dirty_log_manual_caps);
if (ret) {
warn_report("Trying to enable capability %"PRIu64" of "
"KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 but failed. "
"Falling back to the legacy mode. ",
dirty_log_manual_caps);
s->manual_dirty_log_protect = 0;
}
}
}
return 0;
}
static int kvm_init(MachineState *ms)
{
MachineClass *mc = MACHINE_GET_CLASS(ms);
@ -2454,7 +2503,6 @@ static int kvm_init(MachineState *ms)
const KVMCapabilityInfo *missing_cap;
int ret;
int type;
uint64_t dirty_log_manual_caps;
qemu_mutex_init(&kml_slots_lock);
@ -2566,47 +2614,11 @@ static int kvm_init(MachineState *ms)
s->coalesced_pio = s->coalesced_mmio &&
kvm_check_extension(s, KVM_CAP_COALESCED_PIO);
/*
* Enable KVM dirty ring if supported, otherwise fall back to
* dirty logging mode
*/
ret = kvm_dirty_ring_init(s);
ret = kvm_setup_dirty_ring(s);
if (ret < 0) {
goto err;
}
/*
* KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is not needed when dirty ring is
* enabled. More importantly, KVM_DIRTY_LOG_INITIALLY_SET will assume no
* page is wr-protected initially, which is against how kvm dirty ring is
* usage - kvm dirty ring requires all pages are wr-protected at the very
* beginning. Enabling this feature for dirty ring causes data corruption.
*
* TODO: Without KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 and kvm clear dirty log,
* we may expect a higher stall time when starting the migration. In the
* future we can enable KVM_CLEAR_DIRTY_LOG to work with dirty ring too:
* instead of clearing dirty bit, it can be a way to explicitly wr-protect
* guest pages.
*/
if (!s->kvm_dirty_ring_size) {
dirty_log_manual_caps =
kvm_check_extension(s, KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2);
dirty_log_manual_caps &= (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE |
KVM_DIRTY_LOG_INITIALLY_SET);
s->manual_dirty_log_protect = dirty_log_manual_caps;
if (dirty_log_manual_caps) {
ret = kvm_vm_enable_cap(s, KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2, 0,
dirty_log_manual_caps);
if (ret) {
warn_report("Trying to enable capability %"PRIu64" of "
"KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 but failed. "
"Falling back to the legacy mode. ",
dirty_log_manual_caps);
s->manual_dirty_log_protect = 0;
}
}
}
#ifdef KVM_CAP_VCPU_EVENTS
s->vcpu_events = kvm_check_extension(s, KVM_CAP_VCPU_EVENTS);
#endif