Maxim, Sean
On 4/18/22 7:55 PM, Maxim Levitsky wrote:
On Tue, 2022-04-12 at 06:58 -0500, Suravee Suthikulpanit wrote:
When APIC mode is updated (e.g. disabled, xAPIC, or x2APIC),
KVM needs to call kvm_vcpu_update_apicv() to update AVIC settings
accordingly.
Signed-off-by: Suravee Suthikulpanit<suravee.suthikulpanit@xxxxxxx>
---
arch/x86/kvm/svm/avic.c | 15 +++++++++++++++
arch/x86/kvm/svm/svm.c | 1 +
2 files changed, 16 insertions(+)
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 22ee1098e2a5..01392b8364f4 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -616,6 +616,21 @@ void avic_apicv_post_state_restore(struct kvm_vcpu *vcpu)
avic_handle_ldr_update(vcpu);
}
+void avic_set_virtual_apic_mode(struct kvm_vcpu *vcpu)
+{
+ 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 (vcpu_id=%d)", vcpu->vcpu_id);
+ return;
+ }
+
+ kvm_vcpu_update_apicv(&svm->vcpu);
I think it makes sense to call avic_refresh_apicv_exec_ctrl directly here.
I am not sure that kvm_vcpu_update_apicv will even call it
because it has an optimization of doing nothing when inhibition status
didn't change.
Another semi-related note:
the current way the x2avic msrs are configured creates slight performance
problem for nesting:
The problem is that when entering a nested guest, AVIC on the current vCPU
is inhibited, but this is done only so that this vCPU*peers* don't
try to use AVIC to send IPIs to it, so there is no need to update vmcb01
msr interception bitmap, and vmcb02 should have all these msrs intercepted always.
Same with returning to host.
It also should be checked that during nested entry, at least vmcb01 msr bitmap
is updated - TL;DR - please check that x2avic works when there is a nested guest running.
In the kvm/queue branch, I found a regression on nested SVM guest, where L2 guest cannot
launch. The bad commit is:
commit a4cfff3f0f8c07f1f7873a82bdeb3995807dac8c (bisect)
Merge: 42dcbe7d8bac 8d5678a76689
Author: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Date: Fri Apr 8 12:43:40 2022 -0400
Merge branch 'kvm-older-features' into HEAD
Merge branch for features that did not make it into 5.18:
* New ioctls to get/set TSC frequency for a whole VM
* Allow userspace to opt out of hypercall patching
Nested virtualization improvements for AMD:
* Support for "nested nested" optimizations (nested vVMLOAD/VMSAVE,
nested vGIF)
* Allow AVIC to co-exist with a nested guest running
* Fixes for LBR virtualizations when a nested guest is running,
and nested LBR virtualization support
* PAUSE filtering for nested hypervisors
Guest support:
* Decoupling of vcpu_is_preempted from PV spinlocks
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
I am still working on the bisect into the merge commits.
Regards,
Suravee
