Re: [PATCH 3/4] kvm: Create non-coherent DMA registeration

[Alex Williamson]

On Fri, 2013-10-04 at 20:02 +1000, Alexey Kardashevskiy wrote:
> On 10/02/2013 06:15 AM, Alex Williamson wrote:
> > 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 so that we
> > can register coherency for other devices, like vfio assigned devices.
> > 
> > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> > ---
> >  arch/x86/include/asm/kvm_host.h |    2 ++
> >  arch/x86/kvm/vmx.c              |    3 +--
> >  arch/x86/kvm/x86.c              |   21 +++++++++++++++++++--
> >  include/linux/kvm_host.h        |   19 +++++++++++++++++++
> >  virt/kvm/iommu.c                |    6 ++++++
> >  5 files changed, 47 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index 1b6b5f9..50c1e9c1 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -558,6 +558,8 @@ 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 8b2270a..a982c9e 100644
> > --- a/arch/x86/kvm/vmx.c
> > +++ b/arch/x86/kvm/vmx.c
> > @@ -7404,8 +7404,7 @@ 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 b1231b0..feec86d 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -2715,8 +2715,7 @@ 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)
> > @@ -7420,6 +7419,24 @@ 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 f46da56..e239c93 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -671,6 +671,25 @@ 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(void)
> 
> 
> Wrong prototype here and below, must include *kvm.

D'oh.  Thanks

> > +{
> > +}
> > +
> > +static inline void kvm_arch_unregister_noncoherent_dma(void)
> > +{
> > +}
> > +
> > +static inline bool kvm_arch_has_noncoherent_dma(void)
> > +{
> > +	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 9cde444..0a54456 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);
> >  
> > @@ -335,6 +338,9 @@ 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;
> >  }
> >  
> > 
> 
> 



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