From: Sheng Yang <sh...@linux.intel.com> Memory aliases with different memory type is a problem for guest. For the guest without assigned device, the memory type of guest memory would always been the same as host(WB); but for the assigned device, some part of memory may be used as DMA and then set to uncacheable memory type(UC/WC), which would be a conflict of host memory type then be a potential issue.
Snooping control can guarantee the cache correctness of memory go through the DMA engine of VT-d. [avi: fix build on ia64] Signed-off-by: Sheng Yang <sh...@linux.intel.com> Signed-off-by: Avi Kivity <a...@redhat.com> --- arch/ia64/include/asm/kvm_host.h | 1 + arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/vmx.c | 19 +++++++++++++++++-- include/linux/kvm_host.h | 3 +++ virt/kvm/iommu.c | 27 ++++++++++++++++++++++++--- 5 files changed, 46 insertions(+), 5 deletions(-) diff --git a/arch/ia64/include/asm/kvm_host.h b/arch/ia64/include/asm/kvm_host.h index 589536f..5f43697 100644 --- a/arch/ia64/include/asm/kvm_host.h +++ b/arch/ia64/include/asm/kvm_host.h @@ -474,6 +474,7 @@ struct kvm_arch { struct list_head assigned_dev_head; struct iommu_domain *iommu_domain; + int iommu_flags; struct hlist_head irq_ack_notifier_list; unsigned long irq_sources_bitmap; diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 8a6f6b6..253d8f6 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -393,6 +393,7 @@ struct kvm_arch{ struct list_head active_mmu_pages; struct list_head assigned_dev_head; struct iommu_domain *iommu_domain; + int iommu_flags; 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 59b080c..e8a5649 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3581,11 +3581,26 @@ static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) { u64 ret; + /* For VT-d and EPT combination + * 1. MMIO: always map as UC + * 2. EPT with VT-d: + * a. VT-d without snooping control feature: can't guarantee the + * result, try to trust guest. + * b. VT-d with snooping control feature: snooping control feature of + * VT-d engine can guarantee the cache correctness. Just set it + * to WB to keep consistent with host. So the same as item 3. + * 3. EPT without VT-d: always map as WB and set IGMT=1 to keep + * consistent with host MTRR + */ if (is_mmio) ret = MTRR_TYPE_UNCACHABLE << VMX_EPT_MT_EPTE_SHIFT; + else if (vcpu->kvm->arch.iommu_domain && + !(vcpu->kvm->arch.iommu_flags & KVM_IOMMU_CACHE_COHERENCY)) + ret = kvm_get_guest_memory_type(vcpu, gfn) << + VMX_EPT_MT_EPTE_SHIFT; else - ret = (kvm_get_guest_memory_type(vcpu, gfn) << - VMX_EPT_MT_EPTE_SHIFT) | VMX_EPT_IGMT_BIT; + ret = (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT) + | VMX_EPT_IGMT_BIT; return ret; } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 72d5684..bdce8e1 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -367,6 +367,9 @@ void kvm_unregister_irq_ack_notifier(struct kvm_irq_ack_notifier *kian); int kvm_request_irq_source_id(struct kvm *kvm); void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id); +/* For vcpu->arch.iommu_flags */ +#define KVM_IOMMU_CACHE_COHERENCY 0x1 + #ifdef CONFIG_IOMMU_API int kvm_iommu_map_pages(struct kvm *kvm, gfn_t base_gfn, unsigned long npages); diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c index 4c40375..1514758 100644 --- a/virt/kvm/iommu.c +++ b/virt/kvm/iommu.c @@ -39,11 +39,16 @@ int kvm_iommu_map_pages(struct kvm *kvm, pfn_t pfn; int i, r = 0; struct iommu_domain *domain = kvm->arch.iommu_domain; + int flags; /* check if iommu exists and in use */ if (!domain) return 0; + flags = IOMMU_READ | IOMMU_WRITE; + if (kvm->arch.iommu_flags & KVM_IOMMU_CACHE_COHERENCY) + flags |= IOMMU_CACHE; + for (i = 0; i < npages; i++) { /* check if already mapped */ if (iommu_iova_to_phys(domain, gfn_to_gpa(gfn))) @@ -53,8 +58,7 @@ int kvm_iommu_map_pages(struct kvm *kvm, r = iommu_map_range(domain, gfn_to_gpa(gfn), pfn_to_hpa(pfn), - PAGE_SIZE, - IOMMU_READ | IOMMU_WRITE); + PAGE_SIZE, flags); if (r) { printk(KERN_ERR "kvm_iommu_map_address:" "iommu failed to map pfn=%lx\n", pfn); @@ -88,7 +92,7 @@ int kvm_assign_device(struct kvm *kvm, { struct pci_dev *pdev = NULL; struct iommu_domain *domain = kvm->arch.iommu_domain; - int r; + int r, last_flags; /* check if iommu exists and in use */ if (!domain) @@ -107,12 +111,29 @@ int kvm_assign_device(struct kvm *kvm, return r; } + last_flags = kvm->arch.iommu_flags; + if (iommu_domain_has_cap(kvm->arch.iommu_domain, + IOMMU_CAP_CACHE_COHERENCY)) + kvm->arch.iommu_flags |= KVM_IOMMU_CACHE_COHERENCY; + + /* Check if need to update IOMMU page table for guest memory */ + if ((last_flags ^ kvm->arch.iommu_flags) == + KVM_IOMMU_CACHE_COHERENCY) { + kvm_iommu_unmap_memslots(kvm); + r = kvm_iommu_map_memslots(kvm); + if (r) + goto out_unmap; + } + printk(KERN_DEBUG "assign device: host bdf = %x:%x:%x\n", assigned_dev->host_busnr, PCI_SLOT(assigned_dev->host_devfn), PCI_FUNC(assigned_dev->host_devfn)); return 0; +out_unmap: + kvm_iommu_unmap_memslots(kvm); + return r; } int kvm_deassign_device(struct kvm *kvm, -- 1.6.0.6 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html