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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen staging] AMD/IOMMU: re-assign devices directly
commit 1fa6e9aa36233fe9c29a204fcb2697e985b8345f
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Apr 5 14:18:04 2022 +0200
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Apr 5 14:18:04 2022 +0200
AMD/IOMMU: re-assign devices directly
Devices with unity map ranges, due to it being unspecified how/when
these memory ranges may get accessed, may not be left disconnected from
their unity mappings (as long as it's not certain that the device has
been fully quiesced). Hence rather than tearing down the old root page
table pointer and then establishing the new one, re-assignment needs to
be done in a single step.
This is CVE-2022-26360 / part of XSA-400.
Reported-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Similarly quarantining scratch-page mode relies on page tables to be
continuously wired up.
To avoid complicating things more than necessary, treat all devices
mostly equally, i.e. regardless of their association with any unity map
ranges. The main difference is when it comes to updating DTEs, which need
to be atomic when there are unity mappings. Yet atomicity can only be
achieved with CMPXCHG16B, availability of which we can't take for given.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Paul Durrant <paul@xxxxxxx>
Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
xen/drivers/passthrough/amd/iommu.h | 10 +-
xen/drivers/passthrough/amd/iommu_map.c | 67 ++++++++++++-
xen/drivers/passthrough/amd/pci_amd_iommu.c | 142 ++++++++++++++++++++++------
3 files changed, 184 insertions(+), 35 deletions(-)
diff --git a/xen/drivers/passthrough/amd/iommu.h
b/xen/drivers/passthrough/amd/iommu.h
index 0665deeab5..722b92fd78 100644
--- a/xen/drivers/passthrough/amd/iommu.h
+++ b/xen/drivers/passthrough/amd/iommu.h
@@ -263,9 +263,13 @@ void amd_iommu_set_intremap_table(struct amd_iommu_dte
*dte,
const void *ptr,
const struct amd_iommu *iommu,
bool valid);
-void amd_iommu_set_root_page_table(struct amd_iommu_dte *dte,
- uint64_t root_ptr, uint16_t domain_id,
- uint8_t paging_mode, bool valid);
+#define SET_ROOT_VALID (1u << 0)
+#define SET_ROOT_WITH_UNITY_MAP (1u << 1)
+int __must_check amd_iommu_set_root_page_table(struct amd_iommu_dte *dte,
+ uint64_t root_ptr,
+ uint16_t domain_id,
+ uint8_t paging_mode,
+ unsigned int flags);
void iommu_dte_add_device_entry(struct amd_iommu_dte *dte,
const struct ivrs_mappings *ivrs_dev);
diff --git a/xen/drivers/passthrough/amd/iommu_map.c
b/xen/drivers/passthrough/amd/iommu_map.c
index 70089db76d..500a176e47 100644
--- a/xen/drivers/passthrough/amd/iommu_map.c
+++ b/xen/drivers/passthrough/amd/iommu_map.c
@@ -114,10 +114,69 @@ static unsigned int set_iommu_ptes_present(unsigned long
pt_mfn,
return flush_flags;
}
-void amd_iommu_set_root_page_table(struct amd_iommu_dte *dte,
- uint64_t root_ptr, uint16_t domain_id,
- uint8_t paging_mode, bool valid)
+/*
+ * This function returns
+ * - -errno for errors,
+ * - 0 for a successful update, atomic when necessary
+ * - 1 for a successful but non-atomic update, which may need to be warned
+ * about by the caller.
+ */
+int amd_iommu_set_root_page_table(struct amd_iommu_dte *dte,
+ uint64_t root_ptr, uint16_t domain_id,
+ uint8_t paging_mode, unsigned int flags)
{
+ bool valid = flags & SET_ROOT_VALID;
+
+ if ( dte->v && dte->tv &&
+ (cpu_has_cx16 || (flags & SET_ROOT_WITH_UNITY_MAP)) )
+ {
+ union {
+ struct amd_iommu_dte dte;
+ uint64_t raw64[4];
+ __uint128_t raw128[2];
+ } ldte = { .dte = *dte };
+ __uint128_t old = ldte.raw128[0];
+ int ret = 0;
+
+ ldte.dte.domain_id = domain_id;
+ ldte.dte.pt_root = paddr_to_pfn(root_ptr);
+ ldte.dte.iw = true;
+ ldte.dte.ir = true;
+ ldte.dte.paging_mode = paging_mode;
+ ldte.dte.v = valid;
+
+ if ( cpu_has_cx16 )
+ {
+ __uint128_t res = cmpxchg16b(dte, &old, &ldte.raw128[0]);
+
+ /*
+ * Hardware does not update the DTE behind our backs, so the
+ * return value should match "old".
+ */
+ if ( res != old )
+ {
+ printk(XENLOG_ERR
+ "Dom%d: unexpected DTE %016lx_%016lx (expected
%016lx_%016lx)\n",
+ domain_id,
+ (uint64_t)(res >> 64), (uint64_t)res,
+ (uint64_t)(old >> 64), (uint64_t)old);
+ ret = -EILSEQ;
+ }
+ }
+ else /* Best effort, updating domain_id last. */
+ {
+ uint64_t *ptr = (void *)dte;
+
+ write_atomic(ptr + 0, ldte.raw64[0]);
+ /* No barrier should be needed between these two. */
+ write_atomic(ptr + 1, ldte.raw64[1]);
+
+ ret = 1;
+ }
+
+ return ret;
+ }
+
if ( valid || dte->v )
{
dte->tv = false;
@@ -132,6 +191,8 @@ void amd_iommu_set_root_page_table(struct amd_iommu_dte
*dte,
smp_wmb();
dte->tv = true;
dte->v = valid;
+
+ return 0;
}
void amd_iommu_set_intremap_table(
diff --git a/xen/drivers/passthrough/amd/pci_amd_iommu.c
b/xen/drivers/passthrough/amd/pci_amd_iommu.c
index 7b21380a46..38d2e5e15e 100644
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
@@ -96,13 +96,32 @@ static int __must_check allocate_domain_resources(struct
domain *d)
return rc;
}
+static bool any_pdev_behind_iommu(const struct domain *d,
+ const struct pci_dev *exclude,
+ const struct amd_iommu *iommu)
+{
+ const struct pci_dev *pdev;
+
+ for_each_pdev ( d, pdev )
+ {
+ if ( pdev == exclude )
+ continue;
+
+ if ( find_iommu_for_device(pdev->seg, pdev->sbdf.bdf) == iommu )
+ return true;
+ }
+
+ return false;
+}
+
static int __must_check amd_iommu_setup_domain_device(
struct domain *domain, struct amd_iommu *iommu,
uint8_t devfn, struct pci_dev *pdev)
{
struct amd_iommu_dte *table, *dte;
unsigned long flags;
- int req_id, valid = 1, rc;
+ unsigned int req_id, sr_flags;
+ int rc;
u8 bus = pdev->bus;
struct domain_iommu *hd = dom_iommu(domain);
const struct ivrs_mappings *ivrs_dev;
@@ -116,8 +135,11 @@ static int __must_check amd_iommu_setup_domain_device(
if ( rc )
return rc;
- if ( iommu_hwdom_passthrough && is_hardware_domain(domain) )
- valid = 0;
+ req_id = get_dma_requestor_id(iommu->seg, pdev->sbdf.bdf);
+ ivrs_dev = &get_ivrs_mappings(iommu->seg)[req_id];
+ sr_flags = (iommu_hwdom_passthrough && is_hardware_domain(domain)
+ ? 0 : SET_ROOT_VALID)
+ | (ivrs_dev->unity_map ? SET_ROOT_WITH_UNITY_MAP : 0);
/* get device-table entry */
req_id = get_dma_requestor_id(iommu->seg, PCI_BDF2(bus, devfn));
@@ -130,9 +152,15 @@ static int __must_check amd_iommu_setup_domain_device(
if ( !dte->v || !dte->tv )
{
/* bind DTE to domain page-tables */
- amd_iommu_set_root_page_table(
- dte, page_to_maddr(hd->arch.amd.root_table),
- domain->domain_id, hd->arch.amd.paging_mode, valid);
+ rc = amd_iommu_set_root_page_table(
+ dte, page_to_maddr(hd->arch.amd.root_table),
+ domain->domain_id, hd->arch.amd.paging_mode, sr_flags);
+ if ( rc )
+ {
+ ASSERT(rc < 0);
+ spin_unlock_irqrestore(&iommu->lock, flags);
+ return rc;
+ }
/* Undo what amd_iommu_disable_domain_device() may have done. */
if ( dte->it_root )
@@ -152,17 +180,76 @@ static int __must_check amd_iommu_setup_domain_device(
spin_unlock_irqrestore(&iommu->lock, flags);
amd_iommu_flush_device(iommu, req_id);
+ }
+ else if ( dte->pt_root != mfn_x(page_to_mfn(hd->arch.amd.root_table)) )
+ {
+ /*
+ * Strictly speaking if the device is the only one with this requestor
+ * ID, it could be allowed to be re-assigned regardless of unity map
+ * presence. But let's deal with that case only if it is actually
+ * found in the wild.
+ */
+ if ( req_id != PCI_BDF2(bus, devfn) &&
+ (sr_flags & SET_ROOT_WITH_UNITY_MAP) )
+ rc = -EOPNOTSUPP;
+ else
+ rc = amd_iommu_set_root_page_table(
+ dte, page_to_maddr(hd->arch.amd.root_table),
+ domain->domain_id, hd->arch.amd.paging_mode, sr_flags);
+ if ( rc < 0 )
+ {
+ spin_unlock_irqrestore(&iommu->lock, flags);
+ return rc;
+ }
+ if ( rc &&
+ domain != pdev->domain &&
+ /*
+ * By non-atomically updating the DTE's domain ID field last,
+ * during a short window in time TLB entries with the old domain
+ * ID but the new page tables may have been inserted. This could
+ * affect I/O of other devices using this same (old) domain ID.
+ * Such updating therefore is not a problem if this was the only
+ * device associated with the old domain ID. Diverting I/O of any
+ * of a dying domain's devices to the quarantine page tables is
+ * intended anyway.
+ */
+ !pdev->domain->is_dying &&
+ (any_pdev_behind_iommu(pdev->domain, pdev, iommu) ||
+ pdev->phantom_stride) )
+ AMD_IOMMU_WARN(" %pp: reassignment may cause %pd data
corruption\n",
+ &PCI_SBDF3(pdev->seg, bus, devfn), pdev->domain);
+
+ /*
+ * Check remaining settings are still in place from an earlier call
+ * here. They're all independent of the domain, so should not have
+ * changed.
+ */
+ if ( dte->it_root )
+ ASSERT(dte->int_ctl == IOMMU_DEV_TABLE_INT_CONTROL_TRANSLATED);
+ ASSERT(dte->iv == iommu_intremap);
+ ASSERT(dte->ex == ivrs_dev->dte_allow_exclusion);
+ ASSERT(dte->sys_mgt == MASK_EXTR(ivrs_dev->device_flags,
+ ACPI_IVHD_SYSTEM_MGMT));
- AMD_IOMMU_DEBUG("Setup I/O page table: device id = %#x, type = %#x, "
- "root table = %#"PRIx64", "
- "domain = %d, paging mode = %d\n",
- req_id, pdev->type,
- page_to_maddr(hd->arch.amd.root_table),
- domain->domain_id, hd->arch.amd.paging_mode);
+ if ( pci_ats_device(iommu->seg, bus, pdev->devfn) &&
+ !ivrs_dev->block_ats &&
+ iommu_has_cap(iommu, PCI_CAP_IOTLB_SHIFT) )
+ ASSERT(dte->i == ats_enabled);
+
+ spin_unlock_irqrestore(&iommu->lock, flags);
+
+ amd_iommu_flush_device(iommu, req_id);
}
else
spin_unlock_irqrestore(&iommu->lock, flags);
+ AMD_IOMMU_DEBUG("Setup I/O page table: device id = %#x, type = %#x, "
+ "root table = %#"PRIx64", "
+ "domain = %d, paging mode = %d\n",
+ req_id, pdev->type,
+ page_to_maddr(hd->arch.amd.root_table),
+ domain->domain_id, hd->arch.amd.paging_mode);
+
ASSERT(pcidevs_locked());
if ( pci_ats_device(iommu->seg, bus, pdev->devfn) &&
@@ -367,7 +454,20 @@ static int cf_check reassign_device(
return -ENODEV;
}
- amd_iommu_disable_domain_device(source, iommu, devfn, pdev);
+ if ( !QUARANTINE_SKIP(target) )
+ {
+ rc = amd_iommu_setup_domain_device(target, iommu, devfn, pdev);
+ if ( rc )
+ return rc;
+ }
+ else
+ amd_iommu_disable_domain_device(source, iommu, devfn, pdev);
+
+ if ( devfn == pdev->devfn && pdev->domain != target )
+ {
+ list_move(&pdev->domain_list, &target->pdev_list);
+ pdev->domain = target;
+ }
/*
* If the device belongs to the hardware domain, and it has a unity
mapping,
@@ -383,25 +483,9 @@ static int cf_check reassign_device(
return rc;
}
- if ( devfn == pdev->devfn && pdev->domain != dom_io )
- {
- list_move(&pdev->domain_list, &dom_io->pdev_list);
- pdev->domain = dom_io;
- }
-
- rc = amd_iommu_setup_domain_device(target, iommu, devfn, pdev);
- if ( rc )
- return rc;
-
AMD_IOMMU_DEBUG("Re-assign %pp from dom%d to dom%d\n",
&pdev->sbdf, source->domain_id, target->domain_id);
- if ( devfn == pdev->devfn && pdev->domain != target )
- {
- list_move(&pdev->domain_list, &target->pdev_list);
- pdev->domain = target;
- }
-
return 0;
}
--
generated by git-patchbot for /home/xen/git/xen.git#staging
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