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Subject[PATCH v2 4/4] KVM: LAPIC: Don't silently accept bad vectors
Date
From: Wanpeng Li <wanpeng.li@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 <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@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
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