[PATCH v2 4/4] KVM: LAPIC: Don't silently accept bad vectors

[Wanpeng Li]

From: Wanpeng Li <wanpeng...@hotmail.com>

Vectors 0-15 are reserved, and a physical LAPIC - upon sending or
receiving one - would generate an APIC error instead of doing the
requested action. Make our emulation behave similarly.

Cc: Paolo Bonzini <pbonz...@redhat.com>
Cc: Radim Krčmář <rkrc...@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng...@hotmail.com>
---
 arch/x86/kvm/lapic.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 6bafd06..a779ba9 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -935,6 +935,25 @@ bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct 
kvm_lapic_irq *irq,
        return ret;
 }
 
+static void apic_error(struct kvm_lapic *apic, unsigned long errmask)
+{
+       uint32_t esr;
+
+       esr = kvm_lapic_get_reg(apic, APIC_ESR);
+
+       if ((esr & errmask) != errmask) {
+               uint32_t lvterr = kvm_lapic_get_reg(apic, APIC_LVTERR);
+
+               kvm_lapic_set_reg(apic, APIC_ESR, esr | errmask);
+               if (!(lvterr & APIC_LVT_MASKED)) {
+                       struct kvm_lapic_irq irq;
+
+                       irq.vector = lvterr & 0xff;
+                       kvm_irq_delivery_to_apic(apic->vcpu->kvm, apic, &irq, 
NULL);
+               }
+       }
+}
+
 /*
  * Add a pending IRQ into lapic.
  * Return 1 if successfully added and 0 if discarded.
@@ -946,6 +965,11 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int 
delivery_mode,
        int result = 0;
        struct kvm_vcpu *vcpu = apic->vcpu;
 
+       if (unlikely(vector < 16) && delivery_mode == APIC_DM_FIXED) {
+               apic_error(apic, APIC_ESR_RECVILL);
+               return 0;
+       }
+
        trace_kvm_apic_accept_irq(vcpu->vcpu_id, delivery_mode,
                                  trig_mode, vector);
        switch (delivery_mode) {
@@ -1146,7 +1170,10 @@ static void apic_send_ipi(struct kvm_lapic *apic)
                   irq.trig_mode, irq.level, irq.dest_mode, irq.delivery_mode,
                   irq.vector, irq.msi_redir_hint);
 
-       kvm_irq_delivery_to_apic(apic->vcpu->kvm, apic, &irq, NULL);
+       if (unlikely(irq.vector < 16 && irq.delivery_mode == APIC_DM_FIXED))
+               apic_error(apic, APIC_ESR_SENDILL);
+       else
+               kvm_irq_delivery_to_apic(apic->vcpu->kvm, apic, &irq, NULL);
 }
 
 static u32 apic_get_tmcct(struct kvm_lapic *apic)
@@ -1734,7 +1761,6 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, 
u32 val)
        case APIC_LVTPC:
        case APIC_LVT1:
        case APIC_LVTERR:
-               /* TODO: Check vector */
                if (!kvm_apic_sw_enabled(apic))
                        val |= APIC_LVT_MASKED;
 
-- 
2.7.4