This is a note to let you know that I've just added the patch titled
KVM: x86: fix APICv/x2AVIC disabled when vm reboot by itself
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-fix-apicv-x2avic-disabled-when-vm-reboot-by-itself.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ef40757743b47cc95de9b4ed41525c94f8dc73d9 Mon Sep 17 00:00:00 2001
From: Yuan ZhaoXiong <yuanzhaoxiong@xxxxxxxxx>
Date: Fri, 2 Dec 2022 20:36:14 +0800
Subject: KVM: x86: fix APICv/x2AVIC disabled when vm reboot by itself
From: Yuan ZhaoXiong <yuanzhaoxiong@xxxxxxxxx>
commit ef40757743b47cc95de9b4ed41525c94f8dc73d9 upstream.
When a VM reboots itself, the reset process will result in
an ioctl(KVM_SET_LAPIC, ...) to disable x2APIC mode and set
the xAPIC id of the vCPU to its default value, which is the
vCPU id.
That will be handled in KVM as follows:
kvm_vcpu_ioctl_set_lapic
kvm_apic_set_state
kvm_lapic_set_base => disable X2APIC mode
kvm_apic_state_fixup
kvm_lapic_xapic_id_updated
kvm_xapic_id(apic) != apic->vcpu->vcpu_id
kvm_set_apicv_inhibit(APICV_INHIBIT_REASON_APIC_ID_MODIFIED)
memcpy(vcpu->arch.apic->regs, s->regs, sizeof(*s)) => update APIC_ID
When kvm_apic_set_state invokes kvm_lapic_set_base to disable
x2APIC mode, the old 32-bit x2APIC id is still present rather
than the 8-bit xAPIC id. kvm_lapic_xapic_id_updated will set the
APICV_INHIBIT_REASON_APIC_ID_MODIFIED bit and disable APICv/x2AVIC.
Instead, kvm_lapic_xapic_id_updated must be called after APIC_ID is
changed.
In fact, this fixes another small issue in the code in that
potential changes to a vCPU's xAPIC ID need not be tracked for
KVM_GET_LAPIC.
Fixes: 3743c2f02517 ("KVM: x86: inhibit APICv/AVIC on changes to APIC ID or APIC base")
Signed-off-by: Yuan ZhaoXiong <yuanzhaoxiong@xxxxxxxxx>
Message-Id: <1669984574-32692-1-git-send-email-yuanzhaoxiong@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Alejandro Jimenez <alejandro.j.jimenez@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2722,8 +2722,6 @@ static int kvm_apic_state_fixup(struct k
icr = __kvm_lapic_get_reg64(s->regs, APIC_ICR);
__kvm_lapic_set_reg(s->regs, APIC_ICR2, icr >> 32);
}
- } else {
- kvm_lapic_xapic_id_updated(vcpu->arch.apic);
}
return 0;
@@ -2759,6 +2757,9 @@ int kvm_apic_set_state(struct kvm_vcpu *
}
memcpy(vcpu->arch.apic->regs, s->regs, sizeof(*s));
+ if (!apic_x2apic_mode(apic))
+ kvm_lapic_xapic_id_updated(apic);
+
atomic_set_release(&apic->vcpu->kvm->arch.apic_map_dirty, DIRTY);
kvm_recalculate_apic_map(vcpu->kvm);
kvm_apic_set_version(vcpu);
Patches currently in stable-queue which might be from yuanzhaoxiong@xxxxxxxxx are
queue-6.1/kvm-x86-fix-apicv-x2avic-disabled-when-vm-reboot-by-itself.patch
