summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorAlex Williamson <alex.williamson@redhat.com>2013-10-30 11:02:30 -0600
committerPaolo Bonzini <pbonzini@redhat.com>2013-10-30 19:02:23 +0100
commite0f0bbc527f6e9c0261f1d16b2a0b47612b7f235 (patch)
tree623b954e7571767c4d5f0581ad8ba6eacd48785d
parentd96eb2c6f480769bff32054e78b964860dae4d56 (diff)
downloadkernel-e0f0bbc527f6e9c0261f1d16b2a0b47612b7f235.tar.gz
kvm: Create non-coherent DMA registeration
We currently use some ad-hoc arch variables tied to legacy KVM device assignment to manage emulation of instructions that depend on whether non-coherent DMA is present. Create an interface for this, adapting legacy KVM device assignment and adding VFIO via the KVM-VFIO device. For now we assume that non-coherent DMA is possible any time we have a VFIO group. Eventually an interface can be developed as part of the VFIO external user interface to query the coherency of a group. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--arch/x86/include/asm/kvm_host.h2
-rw-r--r--arch/x86/kvm/vmx.c3
-rw-r--r--arch/x86/kvm/x86.c22
-rw-r--r--include/linux/kvm_host.h19
-rw-r--r--virt/kvm/iommu.c6
-rw-r--r--virt/kvm/vfio.c44
6 files changed, 92 insertions, 4 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 91b35e4005d3..de388c55e7ec 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -565,6 +565,8 @@ struct kvm_arch {
struct list_head assigned_dev_head;
struct iommu_domain *iommu_domain;
bool iommu_noncoherent;
+#define __KVM_HAVE_ARCH_NONCOHERENT_DMA
+ atomic_t noncoherent_dma_count;
struct kvm_pic *vpic;
struct kvm_ioapic *vioapic;
struct kvm_pit *vpit;
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 727a5e980c43..fabf7421ec18 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7445,8 +7445,7 @@ static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
*/
if (is_mmio)
ret = MTRR_TYPE_UNCACHABLE << VMX_EPT_MT_EPTE_SHIFT;
- else if (vcpu->kvm->arch.iommu_domain &&
- vcpu->kvm->arch.iommu_noncoherent)
+ else if (kvm_arch_has_noncoherent_dma(vcpu->kvm))
ret = kvm_get_guest_memory_type(vcpu, gfn) <<
VMX_EPT_MT_EPTE_SHIFT;
else
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 92ad83e5b132..ec35d09937da 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2718,8 +2718,7 @@ static void wbinvd_ipi(void *garbage)
static bool need_emulate_wbinvd(struct kvm_vcpu *vcpu)
{
- return vcpu->kvm->arch.iommu_domain &&
- vcpu->kvm->arch.iommu_noncoherent;
+ return kvm_arch_has_noncoherent_dma(vcpu->kvm);
}
void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
@@ -6998,6 +6997,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
INIT_LIST_HEAD(&kvm->arch.zapped_obsolete_pages);
INIT_LIST_HEAD(&kvm->arch.assigned_dev_head);
+ atomic_set(&kvm->arch.noncoherent_dma_count, 0);
/* Reserve bit 0 of irq_sources_bitmap for userspace irq source */
set_bit(KVM_USERSPACE_IRQ_SOURCE_ID, &kvm->arch.irq_sources_bitmap);
@@ -7437,6 +7437,24 @@ bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu)
kvm_x86_ops->interrupt_allowed(vcpu);
}
+void kvm_arch_register_noncoherent_dma(struct kvm *kvm)
+{
+ atomic_inc(&kvm->arch.noncoherent_dma_count);
+}
+EXPORT_SYMBOL_GPL(kvm_arch_register_noncoherent_dma);
+
+void kvm_arch_unregister_noncoherent_dma(struct kvm *kvm)
+{
+ atomic_dec(&kvm->arch.noncoherent_dma_count);
+}
+EXPORT_SYMBOL_GPL(kvm_arch_unregister_noncoherent_dma);
+
+bool kvm_arch_has_noncoherent_dma(struct kvm *kvm)
+{
+ return atomic_read(&kvm->arch.noncoherent_dma_count);
+}
+EXPORT_SYMBOL_GPL(kvm_arch_has_noncoherent_dma);
+
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_page_fault);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ed64880e4915..92aae88756db 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -670,6 +670,25 @@ static inline void kvm_arch_free_vm(struct kvm *kvm)
}
#endif
+#ifdef __KVM_HAVE_ARCH_NONCOHERENT_DMA
+void kvm_arch_register_noncoherent_dma(struct kvm *kvm);
+void kvm_arch_unregister_noncoherent_dma(struct kvm *kvm);
+bool kvm_arch_has_noncoherent_dma(struct kvm *kvm);
+#else
+static inline void kvm_arch_register_noncoherent_dma(struct kvm *kvm)
+{
+}
+
+static inline void kvm_arch_unregister_noncoherent_dma(struct kvm *kvm)
+{
+}
+
+static inline bool kvm_arch_has_noncoherent_dma(struct kvm *kvm)
+{
+ return false;
+}
+#endif
+
static inline wait_queue_head_t *kvm_arch_vcpu_wq(struct kvm_vcpu *vcpu)
{
#ifdef __KVM_HAVE_ARCH_WQP
diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index d32d156a423a..c7d9ce122529 100644
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -140,6 +140,9 @@ static int kvm_iommu_map_memslots(struct kvm *kvm)
struct kvm_memslots *slots;
struct kvm_memory_slot *memslot;
+ if (kvm->arch.iommu_noncoherent)
+ kvm_arch_register_noncoherent_dma(kvm);
+
idx = srcu_read_lock(&kvm->srcu);
slots = kvm_memslots(kvm);
@@ -327,6 +330,9 @@ static int kvm_iommu_unmap_memslots(struct kvm *kvm)
srcu_read_unlock(&kvm->srcu, idx);
+ if (kvm->arch.iommu_noncoherent)
+ kvm_arch_unregister_noncoherent_dma(kvm);
+
return 0;
}
diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 597c258245ea..ca4260e35037 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -27,6 +27,7 @@ struct kvm_vfio_group {
struct kvm_vfio {
struct list_head group_list;
struct mutex lock;
+ bool noncoherent;
};
static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep)
@@ -58,6 +59,43 @@ static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
symbol_put(vfio_group_put_external_user);
}
+/*
+ * Groups can use the same or different IOMMU domains. If the same then
+ * adding a new group may change the coherency of groups we've previously
+ * been told about. We don't want to care about any of that so we retest
+ * each group and bail as soon as we find one that's noncoherent. This
+ * means we only ever [un]register_noncoherent_dma once for the whole device.
+ */
+static void kvm_vfio_update_coherency(struct kvm_device *dev)
+{
+ struct kvm_vfio *kv = dev->private;
+ bool noncoherent = false;
+ struct kvm_vfio_group *kvg;
+
+ mutex_lock(&kv->lock);
+
+ list_for_each_entry(kvg, &kv->group_list, node) {
+ /*
+ * TODO: We need an interface to check the coherency of
+ * the IOMMU domain this group is using. For now, assume
+ * it's always noncoherent.
+ */
+ noncoherent = true;
+ break;
+ }
+
+ if (noncoherent != kv->noncoherent) {
+ kv->noncoherent = noncoherent;
+
+ if (kv->noncoherent)
+ kvm_arch_register_noncoherent_dma(dev->kvm);
+ else
+ kvm_arch_unregister_noncoherent_dma(dev->kvm);
+ }
+
+ mutex_unlock(&kv->lock);
+}
+
static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
{
struct kvm_vfio *kv = dev->private;
@@ -105,6 +143,8 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
mutex_unlock(&kv->lock);
+ kvm_vfio_update_coherency(dev);
+
return 0;
case KVM_DEV_VFIO_GROUP_DEL:
@@ -140,6 +180,8 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
kvm_vfio_group_put_external_user(vfio_group);
+ kvm_vfio_update_coherency(dev);
+
return ret;
}
@@ -185,6 +227,8 @@ static void kvm_vfio_destroy(struct kvm_device *dev)
kfree(kvg);
}
+ kvm_vfio_update_coherency(dev);
+
kfree(kv);
kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */
}