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KVM: Enable snooping control for supported hardware

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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 <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Sheng Yang 2009-04-27 20:35:43 +08:00 committed by Avi Kivity
parent 4b12f0de33
commit 522c68c441
5 changed files with 46 additions and 5 deletions
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1
arch/ia64/include/asm/kvm_host.h
View file

@ -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;

1
arch/x86/include/asm/kvm_host.h
View file

@ -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;

19
arch/x86/kvm/vmx.c
View file

@ -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;
}

3
include/linux/kvm_host.h
View file

@ -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);

27
virt/kvm/iommu.c
View file

@ -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,