XSA-443 and XSA-497 addressed specific issues in specific file system
drivers (libfsimage) used by pygrub. Further issues were reported, and yet
more are to be expected. XSA-443 introduced a means to run pygrub de-
privileged. Only this mode of operation is security supported from now on.
This is XSA-508.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
(cherry picked from commit 75f920bd47)
When doing PoD cache reclaim as part of a decrease reservation call, avoid
reclaiming special pages for the PoD cache. Otherwise such pages get moved
from the domain ->xenpage_list to the ->page_list, while still being
referenced in ->shared_info domain field.
Prevent PoD cache from reclaiming special pages, as nothing good can come
out of it.
This is XSA-507 / CVE-2026-62434.
Fixes: 41aa0b6269 ("PoD memory 4/9: Decrease reservation")
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 372497ce42)
The hypercall requires at least one input buffer, as both arch-specific
implementations of dm_op() unconditionally assume ->buf[0] to be valid (and
not stack rubble).
Additionally, XEN_DMOP_modified_memory requires two input buffers, yet the
code was assuming the second buffer to always be provided by the user when
checking for the number of extents. In case the caller sets nr_bufs to 1,
the code in modified_memory() will read stack garbage as the size of the
buffer, thus allowing the caller some degree of insight on the contents of
the stack by probing whether the hypercall returns -EINVAL or -EFAULT as a
result of such bogus call.
This is XSA-506 / CVE-2026-62433.
Fixes: e3b93b3c59 ("dmop: add xendevicemodel_modified_memory_bulk()")
Fixes: 85cb15dfe4 ("x86/hvm/dmop: only copy what is needed to/from the guest")
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit aef948a300)
evtchn_fifo_expand_array() will check for the domain evtchn_fifo being
populated without holding the event_lock, which can lead to a race with a
concurrent evtchn_reset().
Ensure the checking for evtchn_fifo presence is done while holding the
event_lock.
This is XSA-505 / CVE-2026-62432.
Fixes: 400b3bd642 ("evtchn: make EVTCHNOP_reset suitable for kexec")
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
(cherry picked from commit 0e9d647aca)
Otherwise in periodic mode a division by 0 would happen on the second call
to start_stimer() when using periodic mode.
Note that the HyperV specification states: "Writing the value zero to the
Count register will stop the counter, thereby disabling the timer,
independent of the setting of AutoEnable in the configuration register."
so a timer with a 0 count should never be in the enabled state.
This is XSA-504 / CVE-2026-62431.
Fixes: 26fba3c855 ("viridian: add implementation of synthetic timers")
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit ff7d9aa77e)
Do the checking for a valid CMOS index while holding the spinlock,
otherwise the value could be changed by the guest after having been
checked.
This is XSA-503 / CVE-2026-62430.
Fixes: 34bef0e6d5 ("hvm: Add locking to platform timers.")
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 52350da926)
Calling vnuma_destroy() without any locking can race the handling of both
XENMEM_get_vnumainfo and XEN_DOMCTL_setvnumainfo. While the latter is,
without Flask, strictly only exposed to the control domain, the former
can also be invoked by a stubdom DM or a de-privileged DM running in the
control domain. Isolate the logic used by XEN_DOMCTL_setvnumainfo into a
new helper function, which then is also used from domain_kill(). While
doing so also move the vnuma_destroy() invocation out of the locked
region.
With d->vnuma properly cleared by domain_kill(), XENMEM_get_vnumainfo now
really only needs to check for the field being NULL. That check needs
repeating, though, after re-acquiring the lock.
This is CVE-2026-62429 / XSA-502.
Fixes: 9695014966 ("xen: vnuma topology and subop hypercalls")
Reported-by: Teddy Astie <teddy.astie@vates.tech>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
(cherry picked from commit 2afa6fea9d)
Dropping and re-acquiring the grant table lock for a particular operation
requires special care, as in the meantime the grant table version can
change.
During a v2 -> v1 change, status frames going away means that pre-
calculated status pointers go stale, referencing freed (and possibly
already re-used) memory. Record in-flight v2 operations, permitting the
version change only when there are none of them. Recalculate "status" in
the one place (map_grant_ref()'s error path) where it could be stale, but
confine this to reserved entries.
This is CVE-2026-62436.
Reported-by: Mark Esler <mark@hexproof.dev>
During a v1 -> v2 change, the number of shared table entries reduces,
meaning that previously validated grant references may now be out of
bounds. Because of the checking of pin counts in gnttab_set_version()
(with the grant table lock held for writing), for now-out-of-bounds gref-s
neither active mappings can exist, nor can there be in-progress copy
operations. Nevertheless bounds checks are added there, just to be on the
safe side.
For gnttab_transfer(), to cover the gap between the lock being dropped by
gnttab_prepare_for_transfer() and it being re-acquired, have the helper
return the version it found, and fail the operation if the version turns
out to have changed after re-acquiring the lock.
Further avoid needless use of shared_entry_header(), as it involves
pointer arithmetic which, when using an out-of-bounds ref, is UB.
This is CVE-2026-62435.
Everything together is XSA-501.
Fixes: a98dc13703 ("Introduce a grant_entry_v2 structure")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Mark Esler <mark@hexproof.dev>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
(cherry picked from commit 96dfeb4177)
acquire_grant_for_copy() passes to its caller both an MFN and a struct
page_info *. The two really need to be in sync for the get_page()
underlying get_paged_frame() and get_page_type() (both acting on the
passed back struct page_info *) and the map_domain_page() (acting on the
passed back MFN) to achieve the intended effect.
Go further and also check other properties: GTF_transitive / GTF_sub_page
may have been flipped in the shared entry, so respective fields / values
also may not match.
The one field which we can be sure does match (as it was checked earlier
in the function) is ->domid. Add an assertion nevertheless.
This is CVE-2026-62428 / XSA-500.
Fixes: d8cbecb1ee ("grant-tables: Use get_page_from_gfn() instead of get_gfn()/put_gfn")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
(cherry picked from commit 61b0a59ce2)
Integrate the checking with xsm_sysctl(), now that it has the full op
struct passed. As a positive side effect, permissions are then checked at
the same early point with and without Flask.
This is part of CVE-2026-62426 / XSA-499.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-By: Daniel P. Smith <dpsmith@apertussolutions.com>
(cherry picked from commit 299de2aeda)
Integrate the checking with xsm_sysctl(), now that it has the full op
struct passed. As a positive side effect, permissions are then checked at
the same early point with and without Flask. Note that these were x86-
only, i.e. some dead/unreachable code gets eliminated for (in particular)
Arm.
This is part of CVE-2026-62426 / XSA-499.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-By: Daniel P. Smith <dpsmith@apertussolutions.com>
(cherry picked from commit 0501e1dc04)
Integrate the checking with xsm_sysctl(), now that it has the full op
struct passed. As a positive side effect, permissions are then checked at
the same early point with and without Flask.
This is part of CVE-2026-62426 / XSA-499.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-By: Daniel P. Smith <dpsmith@apertussolutions.com>
(cherry picked from commit 4b249cba4b)
To shield the sysctl lock from abuse by unauthorized domains, follow what
5154fdda11 ("domctl: protect locking for get_domain_state") did: Check
for permission to issue the operation against DOM_XEN in flask_sysctl().
The finer-grained xsm_getdomaininfo() later in the handling of the sub-op
remains unaltered.
In the in-tree policy respective permission therefore needs granting.
This is part of CVE-2026-62426 / XSA-499.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
(cherry picked from commit 3179bf2931)
Integrate the checking with xsm_sysctl(), now that it has the full op
struct passed. As a positive side effect, permissions are then checked at
the same early point with and without Flask.
This is part of CVE-2026-62426 / XSA-499.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-By: Daniel P. Smith <dpsmith@apertussolutions.com>
(cherry picked from commit 751e371c91)
Integrate the checking with flask_platform_op(); there never really was a
need to defer these checks, as the sub-op has always been known to the
function. As a positive side effect, permissions are then checked at the
same early point with and without Flask.
This is CVE-2026-62427 / part of XSA-499.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-By: Daniel P. Smith <dpsmith@apertussolutions.com>
(cherry picked from commit 4ef45cbe31)
The directory and Rock Ridge / SUSP walk in iso9660_dir() derives several
lengths directly from attacker-controlled on-disk fields without validating
them. libfsimage is used by pygrub, which parses the filesystem of an
untrusted guest disk image from dom0, so these are reachable across a trust
boundary.
Five related problems are addressed:
* The directory record loop advances by
idr = (char *)idr + idr->length.l
and only stops on length.l == 0. A record whose length is smaller than
the fixed part of the on-disk layout cannot hold its own mandatory
fields, yet the body still reads name_len/extent/size and computes the
System Use area length from it. Require length to cover at least the
fixed record (sizeof(*idr) - sizeof(idr->name)) before entering the body.
This is CVE-2026-42494.
* The System Use area length is computed before the inner loop as
rr_len = idr->length.l - idr->name_len.l
- sizeof(struct iso_directory_record) + sizeof(idr->name);
in unsigned arithmetic. If length.l is smaller than name_len.l plus the
fixed record size, rr_len underflows to a huge value and the whole SUSP
walk runs off the directory buffer. Guard the subtraction and treat such
records as having no System Use area.
This is CVE-2026-42495.
* Inside the loop, each entry is consumed with
rr_len -= rr_ptr.rr->len;
rr_ptr.ptr += rr_ptr.rr->len;
with no lower or upper bound on the entry's own len byte. A len of 0
spins forever; a len greater than the remaining rr_len underflows it and
walks past the buffer. Validate 4 <= len <= rr_len at the top of the
loop and stop on violation: a structurally broken entry stream cannot be
advanced reliably, so continuing is not meaningful.
This is CVE-2026-62423.
* The NM handler subtracted the 5-byte SUSP/NM header from len without a
lower-bound check, underflowing name_len (the original report). The
generic check above only guarantees len >= 4; NM has an extra flags byte,
so keep an NM-specific len >= 5 check.
This is CVE-2026-62424.
* The CE continuation resets rr_ptr/rr_len from ce.offset and ce.size, both
image-controlled, into the fixed single-sector RRCONT_BUF with no bounds
check. Reject a window that does not fit in the buffer.
This is CVE-2026-62425.
This is XSA-497.
Signed-off-by: Syed Abdul Khaliq <abdul@bugqore.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit fd11acab3d)
Addressing certain issues, in particular related to operations which may
take excessively long and therefore would need preemption, has turned out
overly costly. Since alternatives (HVM/PVH: HAP, PV: shim) are commonly
available, the decision was to deprecate the functionality, while still
retaining it for people to use at their own (security) risk. Memory-wise
small enough guests may still be okay to run.
Some CI testing depends on SHADOW_PAGING. Explicitly enable it when needed.
This is CVE-2026-42493 / XSA-495.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
(cherry picked from commit f2cac32029)
Neither current nor curr_vcpu per-CPU fields accurately track which
page-tables are loaded. There are corner cases when dealing with shadow
paging failures that switch to the idle vCPU page-tables without changing
current or curr_vcpu per-CPU fields.
Introduce a new per-CPU field that attempts to track which vCPU page-tables
are loaded. Update such tracking when cr3 is changed, and do so in a
region with interrupts disabled, as to avoid handling interrupts with a
mismatch between the vCPU tracking field and the loaded page-tables.
As a result of this newly more accurate tracking the mapcache override
functionality can be removed: the dom0 PV builder was the only user of it,
and it's updated here to properly signal which vCPU page-tables are loaded
in the calls to switch_cr3_cr4().
Note the EFI page-tables have the Xen owned L4 slots copied from the idle
page-tables, so for the effects of the mapcache the EFI page-tables could
use the idle mapcache if it had one. Pass the idle vCPU in the
switch_cr3_cr4() call that switches to the runtime EFI page-tables.
There are known issues with the use of mapcache in NMI context. This patch
does not alter the behaviour.
This is CVE-2026-42488 / XSA-494.
Fixes: fb0ff49fe9 ("x86/shadow: defer releasing of PV's top-level shadow reference")
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
(cherry picked from commit 622c9a5ba9)
A number of CPUs developed by Arm suffer from errata whereby a broadcast
TLBI + DSB sequence may complete before the global observation of writes
which are translated by an affected TLB entry. This can lead to memory
corruption and potential privilege escalation.
These errata ONLY affect the completion of memory accesses which have
been translated by an invalidated TLB entry, and these errata DO NOT
affect the actual invalidation of TLB entries. TLB entries are removed
correctly.
To mitigate this issue, Arm recommends that software follows each
TLBI+DSB sequence with an additional TLBI+DSB, which will ensure that
all memory write effects affected by the first TLBI have been globally
observed.
The ARM64_WORKAROUND_REPEAT_TLBI workaround is sufficient to mitigate the
issue. Enable this workaround for affected CPUs.
This is XSA-493 / CVE-2025-10263.
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Julien Grall <julien@xen.org>
(cherry picked from commit 161e8f61b5)
Add processor definitions for C1-Premium. These will be used for errata
detection in subsequent patches.
These values can be found in the C1-Premium TRM:
https://developer.arm.com/documentation/109416/0100/
... in section A.5.1 ("MIDR_EL1, Main ID Register").
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Julien Grall <julien@xen.org>
(cherry picked from commit 0315d10321)
Add processor definitions for C1-Ultra. These will be used for errata
detection in subsequent patches.
These values can be found in the C1-Ultra TRM:
https://developer.arm.com/documentation/108014/0100/
... in section A.5.1 ("MIDR_EL1, Main ID Register").
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Julien Grall <julien@xen.org>
(cherry picked from commit 36ddaa7918)
Synchronize with Linux kernel 7.0 definitions for the following CPUs:
- Cortex-A76AE,
- Cortex-A78AE,
- Cortex-X1C,
- Cortex-X3,
- Neoverse-V2,
- Cortex-X4,
- Neoverse-V3AE,
- Neoverse-V3,
- Cortex-X925.
These will be used for errata detection in subsequent patches.
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Julien Grall <julien@xen.org>
(cherry picked from commit d54682a5b2)
The ARM64_WORKAROUND_REPEAT_TLBI workaround is used to mitigate several
errata where broadcast TLBI;DSB sequences don't provide all the
architecturally required synchronization. The workaround performs more
work than necessary, and can have significant overhead. This patch
optimizes the workaround, as explained below.
1. All relevant errata only affect the ordering and/or completion of
memory accesses which have been translated by an invalidated TLB
entry. The actual invalidation of TLB entries is unaffected.
2. The existing workaround is applied to both broadcast and local TLB
invalidation, whereas for all relevant errata it is only necessary to
apply a workaround for broadcast invalidation.
3. The existing workaround replaces every TLBI with a TLBI;DSB;TLBI
sequence, whereas for all relevant errata it is only necessary to
execute a single additional TLBI;DSB sequence after any number of
TLBIs are completed by a DSB.
For example, for a sequence of batched TLBIs:
TLBI <op1>[, <arg1>]
TLBI <op2>[, <arg2>]
TLBI <op3>[, <arg3>]
DSB ISH
... the existing workaround will expand this to:
TLBI <op1>[, <arg1>]
DSB ISH // additional
TLBI <op1>[, <arg1>] // additional
TLBI <op2>[, <arg2>]
DSB ISH // additional
TLBI <op2>[, <arg2>] // additional
TLBI <op3>[, <arg3>]
DSB ISH // additional
TLBI <op3>[, <arg3>] // additional
DSB ISH
... whereas it is sufficient to have:
TLBI <op1>[, <arg1>]
TLBI <op2>[, <arg2>]
TLBI <op3>[, <arg3>]
DSB ISH
TLBI <opX>[, <argX>] // additional
DSB ISH // additional
Using a single additional TLBI and DSB at the end of the sequence can
have significantly lower overhead as each DSB which completes a TLBI
must synchronize with other PEs in the system, with potential
performance effects both locally and system-wide.
4. The existing workaround repeats each specific TLBI operation, whereas
for all relevant errata it is sufficient for the additional TLBI to
use *any* operation which will be broadcast, regardless of which
translation regime or stage of translation the operation applies to.
For example, for a single TLBI:
TLBI ALLE2IS
DSB ISH
... the existing workaround will expand this to:
TLBI ALLE2IS
DSB ISH
TLBI ALLE2IS // additional
DSB ISH // additional
... whereas it is sufficient to have:
TLBI ALLE2IS
DSB ISH
TLBI VALE1IS, XZR // additional
DSB ISH // additional
As the additional TLBI doesn't have to match a specific earlier TLBI,
the additional TLBI can be implemented in separate code, with no
memory of the earlier TLBIs. The additional TLBI can also use a
cheaper TLBI operation.
5. The existing workaround is applied to both Stage-1 and Stage-2 TLB
invalidation, whereas for all relevant errata it is only necessary to
apply a workaround for Stage-1 invalidation.
Architecturally, TLBI operations which invalidate only Stage-2
information (e.g. IPAS2E1IS) are not required to invalidate TLB
entries which combine information from Stage-1 and Stage-2
translation table entries, and consequently may not complete memory
accesses translated by those combined entries. In these cases,
completion of memory accesses is only guaranteed after subsequent
invalidation of Stage-1 information (e.g. VMALLE1IS).
Rework the workaround logic as follows:
- add TLB_HELPER_LOCAL() to be used for local TLB ops without a
workaround,
- modify TLB_HELPER() workaround to use tlbi vale2is, xzr as a second
TLBI,
- drop TLB_HELPER_VA(). It's used only by __flush_xen_tlb_one_local
which is local and does not need workaround and by
__flush_xen_tlb_one. In the latter case, since it's used in a loop,
we don't need a workaround in the middle. Add __tlb_repeat_sync with
a workaround to be used at the end after DSB and before final ISB,
- TLBI VALE2IS passing XZR is used as an additional TLBI. While there is
an identity mapping there, it's used very rarely. The performance
impact is therefore negligible. If things change in the future, we
can revisit the decision.
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
(cherry picked from commit 7c502d7591)
At the moment, flush_xen_tlb_range_va{,_local}() are using system
wide memory barrier. This is quite expensive and unnecessary.
For the local version, a non-shareable barrier is sufficient.
For the SMP version, an inner-shareable barrier is sufficient.
Furthermore, the initial barrier only needs to a store barrier.
For the full explanation of the sequence see asm/arm{32,64}/flushtlb.h.
Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Henry Wang <Henry.Wang@arm.com>
(cherry picked from commit 5e5d1a43e1)
Per G5-9224 in ARM DDI 0487I.a:
"A DSB NSH is sufficient to ensure completion of TLB maintenance
instructions that apply to a single PE. A DSB ISH is sufficient to
ensure completion of TLB maintenance instructions that apply to PEs
in the same Inner Shareable domain.
"
This is quoting the Armv8 specification because I couldn't find an
explicit statement in the Armv7 specification. Instead, I could find
bits in various places that confirm the same implementation.
Furthermore, Linux has been using 'nsh' since 2013 (62cbbc42e001
"ARM: tlb: reduce scope of barrier domains for TLB invalidation").
This means barrier after local TLB flushes could be reduced to
non-shareable.
Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
Tested-by: Henry Wang <Henry.Wang@arm.com>
(cherry picked from commit d56c70b6e1)
xen/arm: Remove stray semicolon at VREG_REG_HELPERS/TLB_HELPER* callers
This is inconsistent with the rest of the code where macros are used
to define functions, as it results in an empty declaration (i.e.
semicolon with nothing before it) after function definition. This is also
not allowed by C99.
Take the opportunity to undefine TLB_HELPER* macros after last use.
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
(cherry picked from commit 6044b485ba)
Looking at the Neoverse N1 errata document, it is not clear to me
why the TLBI repeat workaround is not applied for TLB flush by VA.
The TLB flush by VA helpers are used in flush_xen_tlb_range_va_local()
and flush_xen_tlb_range_va(). So if the range size is a fixed size smaller
than a PAGE_SIZE, it would be possible that the compiler remove the loop
and therefore replicate the sequence described in the erratum 1286807.
So the TLBI repeat workaround should also be applied for the TLB flush
by VA helpers.
Fixes: 22e323d115 ("xen/arm: Add workaround for Cortex-A76/Neoverse-N1 erratum #1286807")
Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
Tested-by: Henry Wang <Henry.Wang@arm.com>
(cherry picked from commit cbfaf6ccd2)
xen/arm: Remove stray semicolon at VREG_REG_HELPERS/TLB_HELPER* callers
This is inconsistent with the rest of the code where macros are used
to define functions, as it results in an empty declaration (i.e.
semicolon with nothing before it) after function definition. This is also
not allowed by C99.
Take the opportunity to undefine TLB_HELPER* macros after last use.
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
(cherry picked from commit 6044b485ba)
Per D5-4929 in ARM DDI 0487H.a:
"A DSB NSH is sufficient to ensure completion of TLB maintenance
instructions that apply to a single PE. A DSB ISH is sufficient to
ensure completion of TLB maintenance instructions that apply to PEs
in the same Inner Shareable domain.
"
This means barrier after local TLB flushes could be reduced to
non-shareable.
Note that the scope of the barrier in the workaround has not been
changed because Linux v6.1-rc8 is also using 'ish' and I couldn't
find anything in the Neoverse N1 suggesting that a 'nsh' would
be sufficient.
Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
Tested-by: Henry Wang <Henry.Wang@arm.com>
(cherry picked from commit 7c43885147)
xen/arm: Remove stray semicolon at VREG_REG_HELPERS/TLB_HELPER* callers
This is inconsistent with the rest of the code where macros are used
to define functions, as it results in an empty declaration (i.e.
semicolon with nothing before it) after function definition. This is also
not allowed by C99.
Take the opportunity to undefine TLB_HELPER* macros after last use.
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
(cherry picked from commit 6044b485ba)
The only locking required here is that between checking d->target and
setting it. To avoid the need for an explicit lock, use cmpxchgptr() to
update d->target.
Move the handling not only ahead of acquiring the lock, but also ahead
of the XSM check, leveraging that the sub-op has its own hook.
This is part of XSA-492.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
(cherry picked from commit 4a93d1fb4f)
Integrate the checking with xsm_domctl(). As a positive side effect,
permissions are then checked at the same early point with and without
Flask. As the DT device path needs fetching earlier (but must not be
double fetched), cache it in a private field of the public interface
struct.
This is part of XSA-492.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
(cherry picked from commit eab54f074f)
iommu_get_device_group() uses its own locking. Thus, with caller side
locking irrelevant, it can as well be called with the domctl lock not
held.
Move the handling not only ahead of acquiring the lock, but also ahead
of the XSM check, leveraging that the sub-op has its own hook.
This is part of XSA-492.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
(cherry picked from commit 471b377747)
Integrate the checking with xsm_domctl(), now that it has the full op
struct passed. As a positive side effect, permissions are then checked at
the same early point with and without Flask.
This is part of XSA-492.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
(cherry picked from commit d9d2758622)
Integrate the checking with xsm_domctl(), now that it has the full op
struct passed. As a positive side effect, permissions are then checked at
the same early point with and without Flask.
This is part of XSA-492.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
(cherry picked from commit 3ba374d388)
Subsequently some sub-ops will want to inspect their sub-sub-ops. Plus
this way we don't need to pass SSIDref separately anymore for
domain_create.
This is part of XSA-492.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
(cherry picked from commit 83f0e11ed1)
Integrate the checking with xsm_domctl(). Care needs to be taken with the
GET_VERSION sub-op, which may be invoked with DOMID_INVALID, and which has
been (and continues to be) bypassing XSM checking.
Since the latter two parameters were unused, monitor_domctl() invoking the
hook was actually redundant with the earlier xsm_domctl() (as can be seen
nicely from the hunks changing xsm/flask/hooks.c).
As a positive side effect, permissions are then checked at the same early
point with and without Flask.
While folding XEN_DOMCTL_monitor_op and XEN_DOMCTL_vm_event_op in
flask_domctl(), also fold in XEN_DOMCTL_set_access_required.
This is part of XSA-492.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
(cherry picked from commit b4a7c17146)
With dedicated locking added, the domctl lock isn't required here anymore.
Move the re-purposed (XSM_HOOK -> XSM_PRIV, as xsm_domctl() is now
bypassed) dedicated XSM checks as early as possible.
This is part of XSA-492.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
With dedicated locking added, the domctl lock isn't required here anymore.
As the I/O port handling is in arch-specific code (x86 only), no code is
being moved, but the 2nd invocation of arch_do_domctl() is re-used. Move
the re-purposed dedicated XSM checks as early as possible.
This is part of XSA-492.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
(cherry picked from commit 9f54e10bf3)
With dedicated locking added, the domctl lock isn't required here anymore.
(It also already isn't used when pt_irq_{create,destroy}_bind() are
invoked for PVH Dom0.) As the handling is in arch-specific code, no code
is being moved, but the 2nd (extensible to other sub-ops like the ones
here) invocation of arch_do_domctl() is being re-used.
This is part of XSA-492.
Fixes: fda49f9b3f ("Add build option to allow more hypercalls from stubdoms")
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Acked-by: Julien Grall <julien@xen.org>
(cherry picked from commit e263eeaf71)
With dedicated locking added, the domctl lock isn't required here anymore.
As the handling is in arch-specific code (x86 only), almost no code is
being moved, but a 2nd (extensible to other sub-ops) invocation of
arch_do_domctl() is being added. Move just the re-purposed dedicated XSM
check as early as possible.
In flask_domctl() don't put #ifdef around the moved case label.
This is part of XSA-492.
Fixes: fda49f9b3f ("Add build option to allow more hypercalls from stubdoms")
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
(cherry picked from commit 9ac94138a5)
With dedicated locking added, the domctl lock isn't required here anymore.
Move the re-purposed dedicated XSM check as early as possible.
Minimal "modernization": Switch "add" to bool and use %pd in log messages.
This is part of XSA-492.
Fixes: fda49f9b3f ("Add build option to allow more hypercalls from stubdoms")
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
(cherry picked from commit 5a81fb873c)
In order to be able to pull at least the XEN_DOMCTL_{,un}bind_pt_irq
handling out of the domctl-locked region, a separate (per-domain) lock is
needed to synchronize in particular with XEN_DOMCTL_irq_permission.
Locking is added only as far as domctl-s are affected. Uses presently
outside of the domctl lock may want dealing with subsequently (perhaps
limited to non-__init code).
This is part of XSA-492.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Julien Grall <julien@xen.org>
(cherry picked from commit 329edc090d)
In order to be able to pull at least the XEN_DOMCTL_ioport_mapping
handling out of the domctl-locked region, the new separate (per-domain)
lock is used to synchronize in particular with
XEN_DOMCTL_ioport_permission.
Locking is added only as far as domctl-s are affected. Uses presently
outside of the domctl lock may want dealing with subsequently (perhaps
limited to non-__init code).
This is part of XSA-492.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
(cherry picked from commit c9f4586766)
In order to be able to pull at least the XEN_DOMCTL_iomem_mapping handling
out of the domctl-locked region, a separate (per-domain) lock is needed to
synchronize in particular with XEN_DOMCTL_iomem_permission.
Locking is added only as far as domctl-s are affected. Uses presently
outside of the domctl lock may want dealing with subsequently (perhaps
limited to non-__init code).
This is part of XSA-492.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
(cherry picked from commit 960713dfd4)
getdomaininfo() is not called under consistently the same lock. Thus,
with caller side locking irrelevant, it can as well be called with the
domctl lock not held. (Callers not pausing the domain they want to
retrieve information for already need to be aware that not all of the
data returned can be relied on as being consistent; most data will also
be stale by the time the caller gets to look at it.)
Move the handling not only ahead of acquiring the lock, but also ahead
of the XSM check, leveraging that the sub-op has its own hook.
This is part of XSA-492.
Fixes: 5513bd0b46 ("add xenstore domain flag to hypervisor")
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
(cherry picked from commit 784bd4dc0b)
Subsequently XEN_DOMCTL_getdomaininfo will want to invoke the function
without holding a lock, thus allowing parallel execution of potentially
many instances. As was learned from 228ab9992f ("domctl: improve
locking during domain destruction"), reverted by d0887cc6b1, such
parallelism can result in severe lock contention on any (previously)
inner lock. To avoid taking that risk replace the use of the scheduler
lock in vcpu_runstate_get() by a newly introduced sequence counter.
Convert the "no lock if current" property to "use a local counter
instance", thus guaranteeing the loop to exit after the first iteration.
Skeleton and commentary of the seqcount implementation based on /
derived from Linux 6.11-rc.
To have runstate_seq placed next to runstate in struct vcpu, without
introducing a new obvious padding hole, yet while keeping the latter
adjacent to runstate_guest{,_area} as well, move runstate down a little.
This is part of XSA-492.
Requested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
(cherry picked from commit 1dc4d5d818)
Today the dummy XSM privilege checks for getdomaininfo are less
stringent than possible: they basically rely on the general
sysctl/domctl entry check to do all tests and then do the test with
the XSM_HOOK privilege, which is an "allow all" default.
Instead of XSM_HOOK use XSM_XS_PRIV, which is the privilege really
wanted. Note that this test is still wider than the sysctl entry test,
but there is no easy way to make both domctl and sysctl happy at the
same time.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>
master commit: 5793b84c5e
master date: 2024-12-16 13:06:55 +0100
XEN_DOMCTL_ioport_mapping is usable by DM stubdoms, and hence we can't
assume the list to be left unaltered while the guest (really: the
hypervisor on behalf of the guest) is accessing it.
This is XSA-491 / CVE-2026-42487.
Fixes: 192c4dabc3 ("domctl and p2m changes for PCI passthru")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
(cherry picked from commit 7787f8e939)
AMD have updated the SRSO whitepaper[1] with further information. These
features exist on AMD Zen5 CPUs and are necessary for Xen to use.
The two features are in principle unrelated:
* SRSO_U/S_NO is an enumeration saying that SRSO attacks can't cross the
User(CPL3) / Supervisor(CPL<3) boundary. i.e. Xen don't need to use
IBPB-on-entry for PV64. PV32 guests are explicitly unsupported for
speculative issues, and excluded from consideration for simplicity.
* SRSO_MSR_FIX is an enumeration identifying that the BP_SPEC_REDUCE bit is
available in MSR_BP_CFG. When set, SRSO attacks can't cross the host/guest
boundary. i.e. Xen don't need to use IBPB-on-entry for HVM.
Extend ibpb_calculations() to account for these when calculating
opt_ibpb_entry_{pv,hvm} defaults. Add a `bp-spec-reduce=<bool>` option to
control the use of BP_SPEC_REDUCE, with it active by default.
Because MSR_BP_CFG is core-scoped with a race condition updating it, repurpose
amd_check_erratum_1485() into amd_check_bp_cfg() and calculate all updates at
once.
Xen also needs to to advertise SRSO_U/S_NO to guests to allow the guest kernel
to skip SRSO mitigations too:
* This is trivial for HVM guests. It is also is accurate for PV32 guests
too, but we have already excluded them from consideration, and do so again
here to simplify the policy logic.
* As written, SRSO_U/S_NO does not help for the PV64 user->kernel boundary.
However, after discussing with AMD, an implementation detail of having
BP_SPEC_REDUCE active causes the PV64 user->kernel boundary to have the
property described by SRSO_U/S_NO, so we can advertise SRSO_U/S_NO to
guests when the BP_SPEC_REDUCE precondition is met.
Finally, fix a typo in the SRSO_NO's comment.
[1] https://www.amd.com/content/dam/amd/en/documents/corporate/cr/speculative-return-stack-overflow-whitepaper.pdf
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
(cherry picked from commit a1746cd443)
Jan Beulich