Re: [PATCH] KVM: Device Assignment with VT-d

[Laurent Vivier <Laurent.Vivier@bull.net>]

Le mardi 16 septembre 2008 à 00:58 +0000, Avi Kivity a écrit :
> From: Ben-Ami Yassour <benami@il.ibm.com>
> 
> Based on a patch by: Kay, Allen M <allen.m.kay@intel.com>
> 
> This patch enables PCI device assignment based on VT-d support.
> When a device is assigned to the guest, the guest memory is pinned and
> the mapping is updated in the VT-d IOMMU.
> 
> [Amit: Expose KVM_CAP_IOMMU so we can check if an IOMMU is present
> and also control enable/disable from userspace]
> 
> Signed-off-by: Kay, Allen M <allen.m.kay@intel.com>
> Signed-off-by: Weidong Han <weidong.han@intel.com>
> Signed-off-by: Ben-Ami Yassour <benami@il.ibm.com>
> Signed-off-by: Amit Shah <amit.shah@qumranet.com>
> 
> Acked-by: Mark Gross <mgross@linux.intel.com>
> Signed-off-by: Avi Kivity <avi@qumranet.com>
> 
> diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
> index d0e940b..3072b17 100644
> --- a/arch/x86/kvm/Makefile
> +++ b/arch/x86/kvm/Makefile
> @@ -12,6 +12,9 @@ EXTRA_CFLAGS += -Ivirt/kvm -Iarch/x86/kvm
>  
>  kvm-objs := $(common-objs) x86.o mmu.o x86_emulate.o i8259.o irq.o lapic.o \
>  	i8254.o
> +ifeq ($(CONFIG_DMAR),y)
> +kvm-objs += vtd.o
> +endif
>  obj-$(CONFIG_KVM) += kvm.o
>  kvm-intel-objs = vmx.o
>  obj-$(CONFIG_KVM_INTEL) += kvm-intel.o
> diff --git a/arch/x86/kvm/vtd.c b/arch/x86/kvm/vtd.c
> new file mode 100644
> index 0000000..667bf3f
> --- /dev/null
> +++ b/arch/x86/kvm/vtd.c
> @@ -0,0 +1,198 @@
> +/*
> + * Copyright (c) 2006, Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
> + * Place - Suite 330, Boston, MA 02111-1307 USA.
> + *
> + * Copyright (C) 2006-2008 Intel Corporation
> + * Copyright IBM Corporation, 2008
> + * Author: Allen M. Kay <allen.m.kay@intel.com>
> + * Author: Weidong Han <weidong.han@intel.com>
> + * Author: Ben-Ami Yassour <benami@il.ibm.com>
> + */
> +
> +#include <linux/list.h>
> +#include <linux/kvm_host.h>
> +#include <linux/pci.h>
> +#include <linux/dmar.h>
> +#include <linux/intel-iommu.h>
> +
> +static int kvm_iommu_unmap_memslots(struct kvm *kvm);
> +static void kvm_iommu_put_pages(struct kvm *kvm,
> +				gfn_t base_gfn, unsigned long npages);
> +
> +int kvm_iommu_map_pages(struct kvm *kvm,
> +			gfn_t base_gfn, unsigned long npages)
> +{
> +	gfn_t gfn = base_gfn;
> +	pfn_t pfn;
> +	int i, r;
> +	struct dmar_domain *domain = kvm->arch.intel_iommu_domain;
> +
> +	/* check if iommu exists and in use */
> +	if (!domain)
> +		return 0;
> +
> +	r = -EINVAL;
> +	for (i = 0; i < npages; i++) {
> +		/* check if already mapped */
> +		pfn = (pfn_t)intel_iommu_iova_to_pfn(domain,
> +						     gfn_to_gpa(gfn));
> +		if (pfn && !is_mmio_pfn(pfn))
> +			continue;
> +
> +		pfn = gfn_to_pfn(kvm, gfn);
> +		if (!is_mmio_pfn(pfn)) {
> +			r = intel_iommu_page_mapping(domain,
> +						     gfn_to_gpa(gfn),
> +						     pfn_to_hpa(pfn),
> +						     PAGE_SIZE,
> +						     DMA_PTE_READ |
> +						     DMA_PTE_WRITE);
> +			if (r) {
> +				printk(KERN_DEBUG "kvm_iommu_map_pages:"
> +				       "iommu failed to map pfn=%lx\n", pfn);
> +				goto unmap_pages;
> +			}
> +		} else {
> +			printk(KERN_DEBUG "kvm_iommu_map_page:"
> +			       "invalid pfn=%lx\n", pfn);
> +			goto unmap_pages;
> +		}
> +		gfn++;
> +	}
> +	return 0;
> +
> +unmap_pages:
> +	kvm_iommu_put_pages(kvm, base_gfn, i);
> +	return r;
> +}
> +
> +static int kvm_iommu_map_memslots(struct kvm *kvm)
> +{
> +	int i, r;
> +
> +	down_read(&kvm->slots_lock);
> +	for (i = 0; i < kvm->nmemslots; i++) {
> +		r = kvm_iommu_map_pages(kvm, kvm->memslots[i].base_gfn,
> +					kvm->memslots[i].npages);
> +		if (r)
> +			break;
> +	}
> +	up_read(&kvm->slots_lock);
> +	return r;
> +}
> +
> +int kvm_iommu_map_guest(struct kvm *kvm,
> +			struct kvm_assigned_dev_kernel *assigned_dev)
> +{
> +	struct pci_dev *pdev = NULL;
> +	int r;
> +
> +	if (!intel_iommu_found()) {
> +		printk(KERN_ERR "%s: intel iommu not found\n", __func__);
> +		return -ENODEV;
> +	}
> +
> +	printk(KERN_DEBUG "VT-d direct map: host bdf = %x:%x:%x\n",
> +	       assigned_dev->host_busnr,
> +	       PCI_SLOT(assigned_dev->host_devfn),
> +	       PCI_FUNC(assigned_dev->host_devfn));
> +
> +	pdev = assigned_dev->dev;
> +
> +	if (pdev == NULL) {
> +		if (kvm->arch.intel_iommu_domain) {
> +			intel_iommu_domain_exit(kvm->arch.intel_iommu_domain);
> +			kvm->arch.intel_iommu_domain = NULL;
> +		}
> +		return -ENODEV;
> +	}
> +
> +	kvm->arch.intel_iommu_domain = intel_iommu_domain_alloc(pdev);
> +	if (!kvm->arch.intel_iommu_domain)
> +		return -ENODEV;
> +
> +	r = kvm_iommu_map_memslots(kvm);
> +	if (r)
> +		goto out_unmap;
> +
> +	intel_iommu_detach_dev(kvm->arch.intel_iommu_domain,
> +			       pdev->bus->number, pdev->devfn);
> +
> +	r = intel_iommu_context_mapping(kvm->arch.intel_iommu_domain,
> +					pdev);
> +	if (r) {
> +		printk(KERN_ERR "Domain context map for %s failed",
> +		       pci_name(pdev));
> +		goto out_unmap;
> +	}
> +	return 0;
> +
> +out_unmap:
> +	kvm_iommu_unmap_memslots(kvm);
> +	return r;
> +}
> +
> +static void kvm_iommu_put_pages(struct kvm *kvm,
> +			       gfn_t base_gfn, unsigned long npages)
> +{
> +	gfn_t gfn = base_gfn;
> +	pfn_t pfn;
> +	struct dmar_domain *domain = kvm->arch.intel_iommu_domain;
> +	int i;
> +
> +	for (i = 0; i < npages; i++) {
> +		pfn = (pfn_t)intel_iommu_iova_to_pfn(domain,
> +						     gfn_to_gpa(gfn));
> +		kvm_release_pfn_clean(pfn);
> +		gfn++;
> +	}
> +}
> +
> +static int kvm_iommu_unmap_memslots(struct kvm *kvm)
> +{
> +	int i;
> +	down_read(&kvm->slots_lock);
> +	for (i = 0; i < kvm->nmemslots; i++) {
> +		kvm_iommu_put_pages(kvm, kvm->memslots[i].base_gfn,
> +				    kvm->memslots[i].npages);
> +	}
> +	up_read(&kvm->slots_lock);
> +
> +	return 0;
> +}
> +
> +int kvm_iommu_unmap_guest(struct kvm *kvm)
> +{
> +	struct kvm_assigned_dev_kernel *entry;
> +	struct dmar_domain *domain = kvm->arch.intel_iommu_domain;
> +
> +	/* check if iommu exists and in use */
> +	if (!domain)
> +		return 0;
> +
> +	list_for_each_entry(entry, &kvm->arch.assigned_dev_head, list) {
> +		printk(KERN_DEBUG "VT-d unmap: host bdf = %x:%x:%x\n",
> +		       entry->host_busnr,
> +		       PCI_SLOT(entry->host_devfn),
> +		       PCI_FUNC(entry->host_devfn));
> +
> +		/* detach kvm dmar domain */
> +		intel_iommu_detach_dev(domain, entry->host_busnr,
> +				       entry->host_devfn);
> +	}
> +	kvm_iommu_unmap_memslots(kvm);
> +	intel_iommu_domain_exit(domain);
> +	return 0;
> +}
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 2134f3e..c8a2793 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -35,6 +35,7 @@
>  #include <linux/module.h>
>  #include <linux/mman.h>
>  #include <linux/highmem.h>
> +#include <linux/intel-iommu.h>
>  
>  #include <asm/uaccess.h>
>  #include <asm/msr.h>
> @@ -277,9 +278,18 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
>  
>  	list_add(&match->list, &kvm->arch.assigned_dev_head);
>  
> +	if (assigned_dev->flags & KVM_DEV_ASSIGN_ENABLE_IOMMU) {
> +		r = kvm_iommu_map_guest(kvm, match);
> +		if (r)
> +			goto out_list_del;
> +	}
> +
>  out:
>  	mutex_unlock(&kvm->lock);
>  	return r;
> +out_list_del:
> +	list_del(&match->list);
> +	pci_release_regions(dev);
>  out_disable:
>  	pci_disable_device(dev);
>  out_put:
> @@ -1147,6 +1157,9 @@ int kvm_dev_ioctl_check_extension(long ext)
>  	case KVM_CAP_PV_MMU:
>  		r = !tdp_enabled;
>  		break;
> +	case KVM_CAP_IOMMU:
> +		r = intel_iommu_found();
> +		break;

Must depend on CONFIG_DMAR too

Laurent
-- 
----------------- Laurent.Vivier@bull.net  ------------------
  "La perfection est atteinte non quand il ne reste rien à
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