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| author | Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> | 2019-11-14 14:15:16 -0600 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-02-05 15:17:44 +0100 |
| commit | e2ed4078a6ef3ddf4063329298852e24c36d46c8 (patch) | |
| tree | cdd5efeedb8adb92c7ca4177589065bdd3056954 /arch/x86/kvm/i8254.c | |
| parent | f3515dc3bef81e96bdb2ac93ef8fd20b1c2aaae5 (diff) | |
| download | linux-e2ed4078a6ef3ddf4063329298852e24c36d46c8.tar.gz | |
kvm: i8254: Deactivate APICv when using in-kernel PIT re-injection mode.
AMD SVM AVIC accelerates EOI write and does not trap. This causes in-kernel PIT re-injection mode to fail since it relies on irq-ack notifier mechanism. So, APICv is activated only when in-kernel PIT is in discard mode e.g. w/ qemu option: -global kvm-pit.lost_tick_policy=discard Also, introduce APICV_INHIBIT_REASON_PIT_REINJ bit to be used for this reason. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/i8254.c')
| -rw-r--r-- | arch/x86/kvm/i8254.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index 4a6dc54cc12b..b24c606ac04b 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -295,12 +295,24 @@ void kvm_pit_set_reinject(struct kvm_pit *pit, bool reinject) if (atomic_read(&ps->reinject) == reinject) return; + /* + * AMD SVM AVIC accelerates EOI write and does not trap. + * This cause in-kernel PIT re-inject mode to fail + * since it checks ps->irq_ack before kvm_set_irq() + * and relies on the ack notifier to timely queue + * the pt->worker work iterm and reinject the missed tick. + * So, deactivate APICv when PIT is in reinject mode. + */ if (reinject) { + kvm_request_apicv_update(kvm, false, + APICV_INHIBIT_REASON_PIT_REINJ); /* The initial state is preserved while ps->reinject == 0. */ kvm_pit_reset_reinject(pit); kvm_register_irq_ack_notifier(kvm, &ps->irq_ack_notifier); kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier); } else { + kvm_request_apicv_update(kvm, true, + APICV_INHIBIT_REASON_PIT_REINJ); kvm_unregister_irq_ack_notifier(kvm, &ps->irq_ack_notifier); kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier); } |