From: Liu Yi L <yi.l.liu@intel.com>
Date: Thu, 7 Jan 2021 00:03:56 +0800
Subject: iommu/vt-d: Fix general protection fault in aux_detach_device()
Git-commit: 18abda7a2d555783d28ea1701f3ec95e96237a86
Patch-mainline: v5.11-rc3
References: bsc#1183283
The aux-domain attach/detach are not tracked, some data structures might
be used after free. This causes general protection faults when multiple
subdevices are created and assigned to a same guest machine:
| general protection fault, probably for non-canonical address 0xdead000000000100: 0000 [#1] SMP NOPTI
| RIP: 0010:intel_iommu_aux_detach_device+0x12a/0x1f0
| [...]
| Call Trace:
| iommu_aux_detach_device+0x24/0x70
| vfio_mdev_detach_domain+0x3b/0x60
| ? vfio_mdev_set_domain+0x50/0x50
| iommu_group_for_each_dev+0x4f/0x80
| vfio_iommu_detach_group.isra.0+0x22/0x30
| vfio_iommu_type1_detach_group.cold+0x71/0x211
| ? find_exported_symbol_in_section+0x4a/0xd0
| ? each_symbol_section+0x28/0x50
| __vfio_group_unset_container+0x4d/0x150
| vfio_group_try_dissolve_container+0x25/0x30
| vfio_group_put_external_user+0x13/0x20
| kvm_vfio_group_put_external_user+0x27/0x40 [kvm]
| kvm_vfio_destroy+0x45/0xb0 [kvm]
| kvm_put_kvm+0x1bb/0x2e0 [kvm]
| kvm_vm_release+0x22/0x30 [kvm]
| __fput+0xcc/0x260
| ____fput+0xe/0x10
| task_work_run+0x8f/0xb0
| do_exit+0x358/0xaf0
| ? wake_up_state+0x10/0x20
| ? signal_wake_up_state+0x1a/0x30
| do_group_exit+0x47/0xb0
| __x64_sys_exit_group+0x18/0x20
| do_syscall_64+0x57/0x1d0
| entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fix the crash by tracking the subdevices when attaching and detaching
aux-domains.
Fixes: 67b8e02b5e76 ("iommu/vt-d: Aux-domain specific domain attach/detach")
Co-developed-by: Xin Zeng <xin.zeng@intel.com>
Signed-off-by: Xin Zeng <xin.zeng@intel.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/1609949037-25291-3-git-send-email-yi.l.liu@intel.com
Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
drivers/iommu/intel-iommu.c | 96 +++++++++++++++++++++++++++++++++-----------
include/linux/intel-iommu.h | 16 +++++--
2 files changed, 83 insertions(+), 29 deletions(-)
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1737,6 +1737,7 @@ static struct dmar_domain *alloc_domain(
domain->flags = flags;
domain->has_iotlb_device = false;
INIT_LIST_HEAD(&domain->devices);
+ INIT_LIST_HEAD(&domain->subdevices);
return domain;
}
@@ -2498,7 +2499,7 @@ static struct dmar_domain *dmar_insert_o
info->iommu = iommu;
info->pasid_table = NULL;
info->auxd_enabled = 0;
- INIT_LIST_HEAD(&info->auxiliary_domains);
+ INIT_LIST_HEAD(&info->subdevices);
if (dev && dev_is_pci(dev)) {
struct pci_dev *pdev = to_pci_dev(info->dev);
@@ -4981,33 +4982,62 @@ is_aux_domain(struct device *dev, struct
domain->type == IOMMU_DOMAIN_UNMANAGED;
}
-static void auxiliary_link_device(struct dmar_domain *domain,
- struct device *dev)
+static inline struct subdev_domain_info *
+lookup_subdev_info(struct dmar_domain *domain, struct device *dev)
+{
+ struct subdev_domain_info *sinfo;
+
+ if (!list_empty(&domain->subdevices)) {
+ list_for_each_entry(sinfo, &domain->subdevices, link_domain) {
+ if (sinfo->pdev == dev)
+ return sinfo;
+ }
+ }
+
+ return NULL;
+}
+
+static int auxiliary_link_device(struct dmar_domain *domain,
+ struct device *dev)
{
struct device_domain_info *info = get_domain_info(dev);
+ struct subdev_domain_info *sinfo = lookup_subdev_info(domain, dev);
assert_spin_locked(&device_domain_lock);
if (WARN_ON(!info))
- return;
+ return -EINVAL;
- domain->auxd_refcnt++;
- list_add(&domain->auxd, &info->auxiliary_domains);
+ if (!sinfo) {
+ sinfo = kzalloc(sizeof(*sinfo), GFP_ATOMIC);
+ sinfo->domain = domain;
+ sinfo->pdev = dev;
+ list_add(&sinfo->link_phys, &info->subdevices);
+ list_add(&sinfo->link_domain, &domain->subdevices);
+ }
+
+
+ return ++sinfo->users;
}
-static void auxiliary_unlink_device(struct dmar_domain *domain,
- struct device *dev)
+static int auxiliary_unlink_device(struct dmar_domain *domain,
+ struct device *dev)
{
struct device_domain_info *info = get_domain_info(dev);
+ struct subdev_domain_info *sinfo = lookup_subdev_info(domain, dev);
+ int ret;
assert_spin_locked(&device_domain_lock);
- if (WARN_ON(!info))
- return;
+ if (WARN_ON(!info || !sinfo || sinfo->users <= 0))
+ return -EINVAL;
- list_del(&domain->auxd);
- domain->auxd_refcnt--;
+ ret = --sinfo->users;
+ if (!ret) {
+ list_del(&sinfo->link_phys);
+ list_del(&sinfo->link_domain);
+ kfree(sinfo);
+ }
- if (!domain->auxd_refcnt && domain->default_pasid > 0)
- intel_pasid_free_id(domain->default_pasid);
+ return ret;
}
static int aux_domain_add_dev(struct dmar_domain *domain,
@@ -5036,6 +5066,19 @@ static int aux_domain_add_dev(struct dma
}
spin_lock_irqsave(&device_domain_lock, flags);
+ ret = auxiliary_link_device(domain, dev);
+ if (ret <= 0)
+ goto link_failed;
+
+ /*
+ * Subdevices from the same physical device can be attached to the
+ * same domain. For such cases, only the first subdevice attachment
+ * needs to go through the full steps in this function. So if ret >
+ * 1, just goto out.
+ */
+ if (ret > 1)
+ goto out;
+
/*
* iommu->lock must be held to attach domain to iommu and setup the
* pasid entry for second level translation.
@@ -5050,10 +5093,9 @@ static int aux_domain_add_dev(struct dma
domain->default_pasid);
if (ret)
goto table_failed;
- spin_unlock(&iommu->lock);
-
- auxiliary_link_device(domain, dev);
+ spin_unlock(&iommu->lock);
+out:
spin_unlock_irqrestore(&device_domain_lock, flags);
return 0;
@@ -5062,8 +5104,10 @@ table_failed:
domain_detach_iommu(domain, iommu);
attach_failed:
spin_unlock(&iommu->lock);
+ auxiliary_unlink_device(domain, dev);
+link_failed:
spin_unlock_irqrestore(&device_domain_lock, flags);
- if (!domain->auxd_refcnt && domain->default_pasid > 0)
+ if (list_empty(&domain->subdevices) && domain->default_pasid > 0)
intel_pasid_free_id(domain->default_pasid);
return ret;
@@ -5083,14 +5127,18 @@ static void aux_domain_remove_dev(struct
info = get_domain_info(dev);
iommu = info->iommu;
- auxiliary_unlink_device(domain, dev);
-
- spin_lock(&iommu->lock);
- intel_pasid_tear_down_entry(iommu, dev, domain->default_pasid);
- domain_detach_iommu(domain, iommu);
- spin_unlock(&iommu->lock);
+ if (!auxiliary_unlink_device(domain, dev)) {
+ spin_lock(&iommu->lock);
+ intel_pasid_tear_down_entry(iommu, dev,
+ domain->default_pasid);
+ domain_detach_iommu(domain, iommu);
+ spin_unlock(&iommu->lock);
+ }
spin_unlock_irqrestore(&device_domain_lock, flags);
+
+ if (list_empty(&domain->subdevices) && domain->default_pasid > 0)
+ intel_pasid_free_id(domain->default_pasid);
}
static int prepare_domain_attach_device(struct iommu_domain *domain,
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -490,11 +490,10 @@ struct dmar_domain {
/* Domain ids per IOMMU. Use u16 since
* domain ids are 16 bit wide according
* to VT-d spec, section 9.3 */
- unsigned int auxd_refcnt; /* Refcount of auxiliary attaching */
bool has_iotlb_device;
struct list_head devices; /* all devices' list */
- struct list_head auxd; /* link to device's auxiliary list */
+ struct list_head subdevices; /* all subdevices' list */
struct iova_domain iovad; /* iova's that belong to this domain */
struct dma_pte *pgd; /* virtual address */
@@ -562,14 +561,21 @@ struct intel_iommu {
u32 flags; /* Software defined flags */
};
+/* Per subdevice private data */
+struct subdev_domain_info {
+ struct list_head link_phys; /* link to phys device siblings */
+ struct list_head link_domain; /* link to domain siblings */
+ struct device *pdev; /* physical device derived from */
+ struct dmar_domain *domain; /* aux-domain */
+ int users; /* user count */
+};
+
/* PCI domain-device relationship */
struct device_domain_info {
struct list_head link; /* link to domain siblings */
struct list_head global; /* link to global list */
struct list_head table; /* link to pasid table */
- struct list_head auxiliary_domains; /* auxiliary domains
- * attached to this device
- */
+ struct list_head subdevices; /* subdevices sibling */
u8 bus; /* PCI bus number */
u8 devfn; /* PCI devfn number */
u16 pfsid; /* SRIOV physical function source ID */