Hi Maxim,
On 3/24/22 10:35 PM, Maxim Levitsky wrote:
On Tue, 2022-03-08 at 10:39 -0600, Suravee Suthikulpanit wrote:
When APIC mode is updated (e.g. from xAPIC to x2APIC),
KVM needs to update AVIC settings accordingly, whic is
handled by svm_refresh_apicv_exec_ctrl().
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
---
arch/x86/kvm/svm/avic.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 7e5a39a8e698..53559b8dfa52 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -625,7 +625,24 @@ void avic_post_state_restore(struct kvm_vcpu *vcpu)
void svm_set_virtual_apic_mode(struct kvm_vcpu *vcpu)
{
- return;
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ if (!lapic_in_kernel(vcpu) || (avic_mode == AVIC_MODE_NONE))
+ return;
+
+ if (kvm_get_apic_mode(vcpu) == LAPIC_MODE_INVALID)
+ WARN_ONCE(true, "Invalid local APIC state");
+
+ svm->vmcb->control.avic_vapic_bar = svm->vcpu.arch.apic_base &
+ VMCB_AVIC_APIC_BAR_MASK;
No need for that - APIC base relocation doesn't work when AVIC is enabled,
since the page which contains it has to be marked R/W in NPT, which we
only do for the default APIC base.
I recently removed the code from AVIC which still tried to set the
'avic_vapic_bar' like this.
Got it. I'll remove this part.
+ kvm_vcpu_update_apicv(&svm->vcpu);
+
+ /*
+ * The VM could be running w/ AVIC activated switching from APIC
+ * to x2APIC mode. We need to all refresh to make sure that all
+ * x2AVIC configuration are being done.
Why? When AVIC is un-inhibited later then the svm_refresh_apicv_exec_ctrl will be called
again and switch to x2avic mode I think.
Current version does not disable AVIC when APIC is disabled, which happens during
APIC mode switching (i.e. xAPIC -> disabled -> x2APIC). This needs to be fixed.
Then we can remove the force refresh.
When AVIC is inhibited, then regardless of x2apic mode, VMCB must not have
any avic bits set, and all x2apic msrs should be read/write intercepted.,
thus I don't think that svm_refresh_apicv_exec_ctrl should be force called.
The refresh is normally called only when there is APICV update request (e.g.
kvm_request_apicv_update(APICV_INHIBIT_REASON_IRQWIN)), which could happen or not.
However, I have reworked this part. The svm_refresh_apicv_exec_ctrl()
force is no longer needed.
Regards,
Suravee
