there are KVM bugs, ensuring the vCPU and its associated IRTEs are in the
correct state is desirable, i.e. well worth any overhead in a buggy
scenario.
Isolating the "real" load/put flows will allow moving the IOMMU IRTE
(de)activation logic from avic_refresh_apicv_exec_ctrl() to
avic_update_iommu_vcpu_affinity(), i.e. will allow updating the vCPU's
physical ID entry and its IRTEs in a common path, under a single critical
section of ir_list_lock.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/svm/avic.c | 65 +++++++++++++++++++++++------------------
1 file changed, 37 insertions(+), 28 deletions(-)
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 0425cc374a79..d5fa915d0827 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -838,7 +838,7 @@ static void avic_update_iommu_vcpu_affinity(struct kvm_vcpu *vcpu, int cpu)
WARN_ON_ONCE(amd_iommu_update_ga(cpu, ir->data));
}
-void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
+static void __avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
struct kvm_svm *kvm_svm = to_kvm_svm(vcpu->kvm);
int h_physical_id = kvm_cpu_get_apicid(cpu);
@@ -854,16 +854,6 @@ void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
if (WARN_ON_ONCE(vcpu->vcpu_id * sizeof(entry) >= PAGE_SIZE))
return;
- /*
- * No need to update anything if the vCPU is blocking, i.e. if the vCPU
- * is being scheduled in after being preempted. The CPU entries in the
- * Physical APIC table and IRTE are consumed iff IsRun{ning} is '1'.
- * If the vCPU was migrated, its new CPU value will be stuffed when the
- * vCPU unblocks.
- */
- if (kvm_vcpu_is_blocking(vcpu))
- return;
-
/*
* Grab the per-vCPU interrupt remapping lock even if the VM doesn't
* _currently_ have assigned devices, as that can change. Holding
@@ -898,31 +888,33 @@ void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
spin_unlock_irqrestore(&svm->ir_list_lock, flags);
}
-void avic_vcpu_put(struct kvm_vcpu *vcpu)
+void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
+{
+ /*
+ * No need to update anything if the vCPU is blocking, i.e. if the vCPU
+ * is being scheduled in after being preempted. The CPU entries in the
+ * Physical APIC table and IRTE are consumed iff IsRun{ning} is '1'.
+ * If the vCPU was migrated, its new CPU value will be stuffed when the
+ * vCPU unblocks.
+ */
+ if (kvm_vcpu_is_blocking(vcpu))
+ return;
+
+ __avic_vcpu_load(vcpu, cpu);
+}
+
+static void __avic_vcpu_put(struct kvm_vcpu *vcpu)
{
struct kvm_svm *kvm_svm = to_kvm_svm(vcpu->kvm);
struct vcpu_svm *svm = to_svm(vcpu);
unsigned long flags;
- u64 entry;
+ u64 entry = svm->avic_physical_id_entry;
lockdep_assert_preemption_disabled();
if (WARN_ON_ONCE(vcpu->vcpu_id * sizeof(entry) >= PAGE_SIZE))
return;
- /*
- * Note, reading the Physical ID entry outside of ir_list_lock is safe
- * as only the pCPU that has loaded (or is loading) the vCPU is allowed
- * to modify the entry, and preemption is disabled. I.e. the vCPU
- * can't be scheduled out and thus avic_vcpu_{put,load}() can't run
- * recursively.
- */
- entry = svm->avic_physical_id_entry;
-
- /* Nothing to do if IsRunning == '0' due to vCPU blocking. */
- if (!(entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK))
- return;
-
/*
* Take and hold the per-vCPU interrupt remapping lock while updating
* the Physical ID entry even though the lock doesn't protect against
@@ -942,7 +934,24 @@ void avic_vcpu_put(struct kvm_vcpu *vcpu)
WRITE_ONCE(kvm_svm->avic_physical_id_table[vcpu->vcpu_id], entry);
spin_unlock_irqrestore(&svm->ir_list_lock, flags);
+}
+void avic_vcpu_put(struct kvm_vcpu *vcpu)
+{
+ /*
+ * Note, reading the Physical ID entry outside of ir_list_lock is safe
+ * as only the pCPU that has loaded (or is loading) the vCPU is allowed
+ * to modify the entry, and preemption is disabled. I.e. the vCPU
+ * can't be scheduled out and thus avic_vcpu_{put,load}() can't run
+ * recursively.
+ */
+ u64 entry = to_svm(vcpu)->avic_physical_id_entry;
+
+ /* Nothing to do if IsRunning == '0' due to vCPU blocking. */
+ if (!(entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK))
+ return;
+
+ __avic_vcpu_put(vcpu);
}
void avic_refresh_virtual_apic_mode(struct kvm_vcpu *vcpu)
@@ -983,9 +992,9 @@ void avic_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
avic_refresh_virtual_apic_mode(vcpu);
if (activated)
- avic_vcpu_load(vcpu, vcpu->cpu);
+ __avic_vcpu_load(vcpu, vcpu->cpu);
else
- avic_vcpu_put(vcpu);
+ __avic_vcpu_put(vcpu);
/*
* Here, we go through the per-vcpu ir_list to update all existing
