Commit e0f0bbc5 authored by Alex Williamson's avatar Alex Williamson Committed by Paolo Bonzini
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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: default avatarAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent d96eb2c6
......@@ -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;
......
......@@ -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
......
......@@ -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);
......
......@@ -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
......
......@@ -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;
}
......
......@@ -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 */
}
......
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