KVM: count number of assigned devices

If there are no assigned devices, the guest PAT are not providing
any useful information and can be overridden to writeback; VMX
always does this because it has the "IPAT" bit in its extended
page table entries, but SVM does not have anything similar.
Hook into VFIO and legacy device assignment so that they
provide this information to KVM.

Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Joerg Roedel <jroedel@suse.de>
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 2a7f5d782c332d1965ac1c5a23a33289cfce7352..49ec9038ec14102a286c9b4bed126a6825613439 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -604,6 +604,8 @@ struct kvm_arch {
        bool iommu_noncoherent;
 #define __KVM_HAVE_ARCH_NONCOHERENT_DMA
        atomic_t noncoherent_dma_count;
+#define __KVM_HAVE_ARCH_ASSIGNED_DEVICE
+       atomic_t assigned_device_count;
        struct kvm_pic *vpic;
        struct kvm_ioapic *vioapic;
        struct kvm_pit *vpit;

diff --git a/arch/x86/kvm/iommu.c b/arch/x86/kvm/iommu.c
index 7dbced309ddb526d99ae41114bf3afd8488ccaa8..5c520ebf6343270272679e213b19cd9380b63293 100644 (file)
--- a/arch/x86/kvm/iommu.c
+++ b/arch/x86/kvm/iommu.c
@@ -200,6 +200,7 @@ int kvm_assign_device(struct kvm *kvm, struct pci_dev *pdev)
                        goto out_unmap;
        }
 
+       kvm_arch_start_assignment(kvm);
        pci_set_dev_assigned(pdev);
 
        dev_info(&pdev->dev, "kvm assign device\n");
@@ -224,6 +225,7 @@ int kvm_deassign_device(struct kvm *kvm, struct pci_dev *pdev)
        iommu_detach_device(domain, &pdev->dev);
 
        pci_clear_dev_assigned(pdev);
+       kvm_arch_end_assignment(kvm);
 
        dev_info(&pdev->dev, "kvm deassign device\n");
 

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6bd19c7abc6581e6785947e2146a472564dd42f2..0024968b342d75cf53d1a7e158ed94d1ed6e26af 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8213,6 +8213,24 @@ bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu)
                        kvm_x86_ops->interrupt_allowed(vcpu);
 }
 
+void kvm_arch_start_assignment(struct kvm *kvm)
+{
+       atomic_inc(&kvm->arch.assigned_device_count);
+}
+EXPORT_SYMBOL_GPL(kvm_arch_start_assignment);
+
+void kvm_arch_end_assignment(struct kvm *kvm)
+{
+       atomic_dec(&kvm->arch.assigned_device_count);
+}
+EXPORT_SYMBOL_GPL(kvm_arch_end_assignment);
+
+bool kvm_arch_has_assigned_device(struct kvm *kvm)
+{
+       return atomic_read(&kvm->arch.assigned_device_count);
+}
+EXPORT_SYMBOL_GPL(kvm_arch_has_assigned_device);
+
 void kvm_arch_register_noncoherent_dma(struct kvm *kvm)
 {
        atomic_inc(&kvm->arch.noncoherent_dma_count);

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 9564fd78c547b6128ddf8304639e2215b6190e3f..05e99b8ef465bcc10ca979b26b68277191951d86 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -734,6 +734,24 @@ static inline bool kvm_arch_has_noncoherent_dma(struct kvm *kvm)
        return false;
 }
 #endif
+#ifdef __KVM_HAVE_ARCH_ASSIGNED_DEVICE
+void kvm_arch_start_assignment(struct kvm *kvm);
+void kvm_arch_end_assignment(struct kvm *kvm);
+bool kvm_arch_has_assigned_device(struct kvm *kvm);
+#else
+static inline void kvm_arch_start_assignment(struct kvm *kvm)
+{
+}
+
+static inline void kvm_arch_end_assignment(struct kvm *kvm)
+{
+}
+
+static inline bool kvm_arch_has_assigned_device(struct kvm *kvm)
+{
+       return false;
+}
+#endif
 
 static inline wait_queue_head_t *kvm_arch_vcpu_wq(struct kvm_vcpu *vcpu)
 {

diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 620e37f741b868a231a414a71511cd8872704a3c..1dd087da6f31ae2f38c70042213ee6e5159cee10 100644 (file)
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -155,6 +155,8 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
                list_add_tail(&kvg->node, &kv->group_list);
                kvg->vfio_group = vfio_group;
 
+               kvm_arch_start_assignment(dev->kvm);
+
                mutex_unlock(&kv->lock);
 
                kvm_vfio_update_coherency(dev);
@@ -190,6 +192,8 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
                        break;
                }
 
+               kvm_arch_end_assignment(dev->kvm);
+
                mutex_unlock(&kv->lock);
 
                kvm_vfio_group_put_external_user(vfio_group);
@@ -239,6 +243,7 @@ static void kvm_vfio_destroy(struct kvm_device *dev)
                kvm_vfio_group_put_external_user(kvg->vfio_group);
                list_del(&kvg->node);
                kfree(kvg);
+               kvm_arch_end_assignment(dev->kvm);
        }
 
        kvm_vfio_update_coherency(dev);