KVM: x86: Disable posted interrupts for non-standard IRQs delivery modes

We can easily route hardware interrupts directly into VM context when
they target the "Fixed" or "LowPriority" delivery modes.

However, on modes such as "SMI" or "Init", we need to go via KVM code
to actually put the vCPU into a different mode of operation, so we can
not post the interrupt

Add code in the VMX and SVM PI logic to explicitly refuse to establish
posted mappings for advanced IRQ deliver modes. This reflects the logic
in __apic_accept_irq() which also only ever passes Fixed and LowPriority
interrupts as posted interrupts into the guest.

This fixes a bug I have with code which configures real hardware to
inject virtual SMIs into my guest.

Signed-off-by: Alexander Graf <graf@amazon.com>
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Wanpeng Li <wanpengli@tencent.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 44a5ce57a9051f6addeaaaf77280c9f4e5219947..5b14aa1fbeebe2aa32f0b67953c71b8331fc246c 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1581,6 +1581,13 @@ bool kvm_intr_is_single_vcpu(struct kvm *kvm, struct kvm_lapic_irq *irq,
 void kvm_set_msi_irq(struct kvm *kvm, struct kvm_kernel_irq_routing_entry *e,
                     struct kvm_lapic_irq *irq);
 
+static inline bool kvm_irq_is_postable(struct kvm_lapic_irq *irq)
+{
+       /* We can only post Fixed and LowPrio IRQs */
+       return (irq->delivery_mode == dest_Fixed ||
+               irq->delivery_mode == dest_LowestPrio);
+}
+
 static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu)
 {
        if (kvm_x86_ops->vcpu_blocking)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 1f220a85514fad1f9ade1554e9e16039eecd6d00..f5b03d0c9bc61f901f28208637502d961ce7b487 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5260,7 +5260,8 @@ get_pi_vcpu_info(struct kvm *kvm, struct kvm_kernel_irq_routing_entry *e,
 
        kvm_set_msi_irq(kvm, e, &irq);
 
-       if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu)) {
+       if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu) ||
+           !kvm_irq_is_postable(&irq)) {
                pr_debug("SVM: %s: use legacy intr remap mode for irq %u\n",
                         __func__, irq.vector);
                return -1;
@@ -5314,6 +5315,7 @@ static int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
                 * 1. When cannot target interrupt to a specific vcpu.
                 * 2. Unsetting posted interrupt.
                 * 3. APIC virtialization is disabled for the vcpu.
+                * 4. IRQ has incompatible delivery mode (SMI, INIT, etc)
                 */
                if (!get_pi_vcpu_info(kvm, e, &vcpu_info, &svm) && set &&
                    kvm_vcpu_apicv_active(&svm->vcpu)) {

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 570a233e272bb43d8b5fe2c7822ca5b26805293c..63f3d88b36cc14f69cd01ae06d12f502e4ea1a02 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7382,10 +7382,14 @@ static int vmx_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
                 * irqbalance to make the interrupts single-CPU.
                 *
                 * We will support full lowest-priority interrupt later.
+                *
+                * In addition, we can only inject generic interrupts using
+                * the PI mechanism, refuse to route others through it.
                 */
 
                kvm_set_msi_irq(kvm, e, &irq);
-               if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu)) {
+               if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu) ||
+                   !kvm_irq_is_postable(&irq)) {
                        /*
                         * Make sure the IRTE is in remapped mode if
                         * we don't handle it in posted mode.