diff options
| author | Dr. David Alan Gilbert <dgilbert@redhat.com> | 2017-11-17 12:52:50 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2017-11-27 17:32:53 +0100 |
| commit | 12806ba937382fdfdbad62a399aa2dce65c10fcd (patch) | |
| tree | 20498528e5a025aedf97ef2728259b054368ee90 | |
| parent | KVM: lapic: Split out x2apic ldr calculation (diff) | |
| download | linux-12806ba937382fdfdbad62a399aa2dce65c10fcd.tar.xz linux-12806ba937382fdfdbad62a399aa2dce65c10fcd.zip | |
KVM: lapic: Fixup LDR on load in x2apic
In x2apic mode the LDR is fixed based on the ID rather
than separately loadable like it was before x2.
When kvm_apic_set_state is called, the base is set, and if
it has the X2APIC_ENABLE flag set then the LDR is calculated;
however that value gets overwritten by the memcpy a few lines
below overwriting it with the value that came from userland.
The symptom is a lack of EOI after loading the state
(e.g. after a QEMU migration) and is due to the EOI bitmap
being wrong due to the incorrect LDR. This was seen with
a Win2016 guest under Qemu with irqchip=split whose USB mouse
didn't work after a VM migration.
This corresponds to RH bug:
https://bugzilla.redhat.com/show_bug.cgi?id=1502591
Reported-by: Yiqian Wei <yiwei@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: stable@vger.kernel.org
[Applied fixup from Liran Alon. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/lapic.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index e2edb1103002..e2c1fb8d35ce 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2250,6 +2250,7 @@ static int kvm_apic_state_fixup(struct kvm_vcpu *vcpu, { if (apic_x2apic_mode(vcpu->arch.apic)) { u32 *id = (u32 *)(s->regs + APIC_ID); + u32 *ldr = (u32 *)(s->regs + APIC_LDR); if (vcpu->kvm->arch.x2apic_format) { if (*id != vcpu->vcpu_id) @@ -2260,6 +2261,10 @@ static int kvm_apic_state_fixup(struct kvm_vcpu *vcpu, else *id <<= 24; } + + /* In x2APIC mode, the LDR is fixed and based on the id */ + if (set) + *ldr = kvm_apic_calc_x2apic_ldr(*id); } return 0; |