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Commit 522c68c4 authored by Sheng Yang's avatar Sheng Yang Committed by Avi Kivity
Browse files

KVM: Enable snooping control for supported hardware 



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: default avatarSheng Yang <sheng@linux.intel.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 4b12f0de

arch/ia64/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

arch/x86/kvm/vmx.c

+17 −2
Original line number Diff line number Diff line
@@ -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;

}

include/linux/kvm_host.h

+3 −0
Original line number Diff line number Diff line
@@ -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);

virt/kvm/iommu.c

+24 −3
Original line number Diff line number Diff line
@@ -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,