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From b378ee56c7e0bb5eeb35dcc55b3d29e5f50eb566 Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Tue, 7 Jun 2022 13:58:16 +0200
Subject: [PATCH 04/51] VT-d: refuse to use IOMMU with reserved CAP.ND value
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
The field taking the value 7 (resulting in 18-bit DIDs when using the
calculation in cap_ndoms(), when the DID fields are only 16 bits wide)
is reserved. Instead of misbehaving in case we would encounter such an
IOMMU, refuse to use it.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
master commit: a1545fbf45c689aff39ce76a6eaa609d32ef72a7
master date: 2022-04-20 10:54:26 +0200
---
xen/drivers/passthrough/vtd/iommu.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/xen/drivers/passthrough/vtd/iommu.c b/xen/drivers/passthrough/vtd/iommu.c
index 93dd8aa643aa..8975c1de61bc 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1279,8 +1279,11 @@ int __init iommu_alloc(struct acpi_drhd_unit *drhd)
quirk_iommu_caps(iommu);
+ nr_dom = cap_ndoms(iommu->cap);
+
if ( cap_fault_reg_offset(iommu->cap) +
cap_num_fault_regs(iommu->cap) * PRIMARY_FAULT_REG_LEN >= PAGE_SIZE ||
+ ((nr_dom - 1) >> 16) /* I.e. cap.nd > 6 */ ||
ecap_iotlb_offset(iommu->ecap) >= PAGE_SIZE )
{
printk(XENLOG_ERR VTDPREFIX "IOMMU: unsupported\n");
@@ -1305,7 +1308,6 @@ int __init iommu_alloc(struct acpi_drhd_unit *drhd)
vtd_ops.sync_cache = sync_cache;
/* allocate domain id bitmap */
- nr_dom = cap_ndoms(iommu->cap);
iommu->domid_bitmap = xzalloc_array(unsigned long, BITS_TO_LONGS(nr_dom));
if ( !iommu->domid_bitmap )
return -ENOMEM;
--
2.35.1
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