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Commit e0f0bbc5 authored by Alex Williamson's avatar Alex Williamson Committed by Paolo Bonzini
Browse files

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

arch/x86/include/asm/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -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;

arch/x86/kvm/vmx.c

+1 −2
Original line number Diff line number Diff line
@@ -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

arch/x86/kvm/x86.c

+20 −2
Original line number Diff line number Diff line
@@ -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);

include/linux/kvm_host.h

+19 −0
Original line number Diff line number Diff line
@@ -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

virt/kvm/iommu.c

+6 −0
Original line number Diff line number Diff line
@@ -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;

}