From: Dr. David Alan Gilbert Date: Fri, 17 Nov 2017 11:52:50 +0000 (+0000) Subject: KVM: lapic: Fixup LDR on load in x2apic X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=81b3019c35d650e7570ff016ba0732ba6d62c466;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git KVM: lapic: Fixup LDR on load in x2apic commit 12806ba937382fdfdbad62a399aa2dce65c10fcd upstream. 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 Signed-off-by: Dr. David Alan Gilbert [Applied fixup from Liran Alon. - Paolo] Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 4991e9e51611..ef03efba1c23 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2201,6 +2201,7 @@ 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) @@ -2211,6 +2212,10 @@ 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;