The NFS client needs to defer dropbehind until after any writes to the
folio have been persisted on the server. Since this may be a 2 step
process, use folio_end_writeback_no_dropbehind() to allow release of the
writeback flag, and then call folio_end_dropbehind() once the COMMIT is
done.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Filesystems such as NFS may need to defer dropbehind until after their
2-stage writes are done. This adds a helper
folio_end_writeback_no_dropbehind() that allows them to release the
writeback flag without immediately dropping the folio.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
This was the last caller of xdr_set_scratch_page(), so I remove this
function while I'm at it.
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
The only snag here is that __folio_alloc_node() doesn't handle
NUMA_NO_NODE, so I also need to update svc_pool_map_get_node() to return
numa_mem_id() instead. I arrived at this approach by looking at what
other users of __folio_alloc_node() do for this case.
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
GFP_NOWAIT already includes __GFP_NOWARN, so let's remove the redundant
__GFP_NOWARN.
Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Clean up: because svc_rpcb_cleanup() and svc_xprt_destroy_all()
are always invoked in pairs, we can deduplicate code by moving
the svc_rpcb_cleanup() call sites into svc_xprt_destroy_all().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Olga Kornievskaia <okorniev@redhat.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
The NFS client's NFSv4.0 callback listeners are created with
SVC_SOCK_ANONYMOUS, therefore svc_setup_socket() does not register
them with the client's rpcbind service.
And, note that nfs_callback_down_net() does not call
svc_rpcb_cleanup() at all when shutting down the callback server.
Even if svc_setup_socket() were to attempt to register or unregister
these sockets, the callback service has vs_hidden set, which shunts
the rpcbind upcalls.
The svc_rpcb_cleanup() error flow was introduced by
commit c946556b87 ("NFS: move per-net callback thread
initialization to nfs_callback_up_net()"). It doesn't appear in the
code that was relocated by that commit.
Therefore, there is no need to call svc_rpcb_cleanup() when listener
creation fails during callback server start-up.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
When client initialization goes through server trunking discovery, it
schedules the state manager and then sleeps waiting for nfs_client
initialization completion.
The state manager can fail during state recovery, and specifically in
lease establishment as nfs41_init_clientid() will bail out in case of
errors returned from nfs4_proc_create_session(), without ever marking
the client ready. The session creation can fail for a variety of reasons
e.g. during backchannel parameter negotiation, with status -EINVAL.
The error status will propagate all the way to the nfs4_state_manager
but the client status will not be marked, and thus the mount process
will remain blocked waiting.
Fix it by adding -EINVAL error handling to nfs4_state_manager().
Signed-off-by: Anthony Iliopoulos <ailiop@suse.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
When the client max_resp_sz is larger than what the server encodes in
its reply, the nfs4_verify_back_channel_attrs() check fails and this
causes nfs4_proc_create_session() to fail, in cases where the client
page size is larger than that of the server and the server does not want
to negotiate upwards.
While this is not a problem with the linux nfs server that will reflect
the proposed value in its reply irrespective of the local page size,
other nfs server implementations may insist on their own max_resp_sz
value, which could be smaller.
Fix this by accepting smaller max_resp_sz values from the server, as
this does not violate the protocol. The server is allowed to decrease
but not increase proposed the size, and as such values smaller than the
client-proposed ones are valid.
Fixes: 43c2e885be ("nfs4: fix channel attribute sanity-checks")
Signed-off-by: Anthony Iliopoulos <ailiop@suse.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Trivial fix to spelling mistake in comment text.
Signed-off-by: Xichao Zhao <zhao.xichao@vivo.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
RFC7530 states that clients should be prepared for the return of
NFS4ERR_GRACE errors for non-reclaim lock and I/O requests.
Signed-off-by: Olga Kornievskaia <okorniev@redhat.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
We have a lot of old dprintk() call sites that aren't going anywhere
anytime soon. At the same time, turning them up is a serious burden on
the host due to the console locking overhead.
Add a new Kconfig option that redirects dfprintk() output to the trace
buffer. This is more efficient than logging to the console and allows
for proper interleaving of dprintk and static tracepoint events.
Since using trace_printk() causes scary warnings to pop at boot time,
this new option defaults to "n".
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
KERN_CONT hails from a simpler time, when SMP wasn't the norm. These
days, it doesn't quite work right since another printk() can always race
in between the first one and the one being "continued".
Nothing calls dprintk_rcu_cont(), so just remove it. The only caller of
dprintk_cont() is in nfs_commit_release_pages(). Just use a normal
dprintk() there instead, since this is not SMP-safe anyway.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Cleanup tracepoint declarations by replacing commas with
semicolons to better match other tracepoint declarations.
No functional changes introduced.
Signed-off-by: Leo Martins <loemra.dev@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Show the inode info and requested range.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Add tracepoints to nfs_writepage_setup() and nfs_do_writepage().
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
New start and done tracepoints for:
nfs_update_folio()
nfs_write_begin()
nfs_write_end()
nfs_try_to_update_request()
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Add some tracepoints to the I/O submission codepaths.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Make CR4.CET a guest-owned bit under VMX by extending
KVM_POSSIBLE_CR4_GUEST_BITS accordingly.
There's no need to intercept changes to CR4.CET, as it's neither
included in KVM's MMU role bits, nor does KVM specifically care about
the actual value of a (nested) guest's CR4.CET value, beside for
enforcing architectural constraints, i.e. make sure that CR0.WP=1 if
CR4.CET=1.
Intercepting writes to CR4.CET is particularly bad for grsecurity
kernels with KERNEXEC or, even worse, KERNSEAL enabled. These features
heavily make use of read-only kernel objects and use a cpu-local CR0.WP
toggle to override it, when needed. Under a CET-enabled kernel, this
also requires toggling CR4.CET, hence the motivation to make it
guest-owned.
Using the old test from [1] gives the following runtime numbers (perf
stat -r 5 ssdd 10 50000):
* grsec guest on linux-6.16-rc5 + cet patches:
2.4647 +- 0.0706 seconds time elapsed ( +- 2.86% )
* grsec guest on linux-6.16-rc5 + cet patches + CR4.CET guest-owned:
1.5648 +- 0.0240 seconds time elapsed ( +- 1.53% )
Not only does not intercepting CR4.CET make the test run ~35% faster,
it's also more stable with less fluctuation due to fewer VMEXITs.
Therefore, make CR4.CET a guest-owned bit where possible.
This change is VMX-specific, as SVM has no such fine-grained control
register intercept control.
If KVM's assumptions regarding MMU role handling wrt. a guest's CR4.CET
value ever change, the BUILD_BUG_ON()s related to KVM_MMU_CR4_ROLE_BITS
and KVM_POSSIBLE_CR4_GUEST_BITS will catch that early.
Link: https://lore.kernel.org/kvm/20230322013731.102955-1-minipli@grsecurity.net/ [1]
Reviewed-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-52-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add a check in the MSRs test to verify that KVM's reported support for
MSRs with feature bits is consistent between KVM's MSR save/restore lists
and KVM's supported CPUID.
To deal with Intel's wonderful decision to bundle IBT and SHSTK under CET,
track the "second" feature to avoid false failures when running on a CPU
with only one of IBT or SHSTK.
Reviewed-by: Chao Gao <chao.gao@intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-51-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add test coverage for the KVM-defined GUEST_SSP "register" in the MSRs
test. While _KVM's_ goal is to not tie the uAPI of KVM-defined registers
to any particular internal implementation, i.e. to not commit in uAPI to
handling GUEST_SSP as an MSR, treating GUEST_SSP as an MSR for testing
purposes is a-ok and is a naturally fit given the semantics of SSP.
Reviewed-by: Chao Gao <chao.gao@intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-50-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
When KVM_{G,S}ET_ONE_REG are supported, verify that MSRs can be accessed
via ONE_REG and through the dedicated MSR ioctls. For simplicity, run
the test twice, e.g. instead of trying to get MSR values into the exact
right state when switching write methods.
Reviewed-by: Chao Gao <chao.gao@intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-49-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add a third vCPUs to the MSRs test that runs with all features disabled in
the vCPU's CPUID model, to verify that KVM does the right thing with
respect to emulating accesses to MSRs that shouldn't exist. Use the same
VM to verify that KVM is honoring the vCPU model, e.g. isn't looking at
per-VM state when emulating MSR accesses.
Link: https://lore.kernel.org/r/20250919223258.1604852-48-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Extend the MSRs test to support {S,U}_CET, which are a bit of a pain to
handled due to the MSRs existing if IBT *or* SHSTK is supported. To deal
with Intel's wonderful decision to bundle IBT and SHSTK under CET, track
the second feature, but skip only RDMSR #GP tests to avoid false failures
when running on a CPU with only one of IBT or SHSTK (the WRMSR #GP tests
are still valid since the enable bits are per-feature).
Reviewed-by: Chao Gao <chao.gao@intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-47-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add a selftest to verify reads and writes to various MSRs, from both the
guest and host, and expect success/failure based on whether or not the
vCPU supports the MSR according to supported CPUID.
Note, this test is extremely similar to KVM-Unit-Test's "msr" test, but
provides more coverage with respect to host accesses, and will be extended
to provide addition testing of CPUID-based features, save/restore lists,
and KVM_{G,S}ET_ONE_REG, all which are extremely difficult to validate in
KUT.
If kvm.ignore_msrs=true, skip the unsupported and reserved testcases as
KVM's ABI is a mess; what exactly is supposed to be ignored, and when,
varies wildly.
Reviewed-by: Chao Gao <chao.gao@intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-46-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add {HV,CP,SX}_VECTOR definitions for AMD's Hypervisor Injection Exception,
VMM Communication Exception, and SVM Security Exception vectors, along with
human friendly formatting for trace_kvm_inj_exception().
Note, KVM is all but guaranteed to never observe or inject #SX, and #HV is
also unlikely to go unused. Add the architectural collateral mostly for
completeness, and on the off chance that hardware goes off the rails.
Link: https://lore.kernel.org/r/20250919223258.1604852-44-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add a CP_VECTOR definition for CET's Control Protection Exception (#CP),
along with human friendly formatting for trace_kvm_inj_exception().
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-43-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Remove the explicit clearing of shadow stack CPU capabilities.
Reviewed-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: John Allen <john.allen@amd.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-41-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Synchronize XSS from the GHCB to KVM's internal tracking if the guest
marks XSS as valid on a #VMGEXIT. Like XCR0, KVM needs an up-to-date copy
of XSS in order to compute the required XSTATE size when emulating
CPUID.0xD.0x1 for the guest.
Treat the incoming XSS change as an emulated write, i.e. validatate the
guest-provided value, to avoid letting the guest load garbage into KVM's
tracking. Simply ignore bad values, as either the guest managed to get an
unsupported value into hardware, or the guest is misbehaving and providing
pure garbage. In either case, KVM can't fix the broken guest.
Explicitly allow access to XSS at all times, as KVM needs to ensure its
copy of XSS stays up-to-date. E.g. KVM supports migration of SEV-ES guests
and so needs to allow the host to save/restore XSS, otherwise a guest
that *knows* its XSS hasn't change could get stale/bad CPUID emulation if
the guest doesn't provide XSS in the GHCB on every exit. This creates a
hypothetical problem where a guest could request emulation of RDMSR or
WRMSR on XSS, but arguably that's not even a problem, e.g. it would be
entirely reasonable for a guest to request "emulation" as a way to inform
the hypervisor that its XSS value has been modified.
Note, emulating the change as an MSR write also takes care of side effects,
e.g. marking dynamic CPUID bits as dirty.
Suggested-by: John Allen <john.allen@amd.com>
base-commit: 14298d819d5a6b7180a4089e7d2121ca3551dc6c
Link: https://lore.kernel.org/r/20250919223258.1604852-40-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Pass through XSAVE managed CET MSRs on SVM when KVM supports shadow
stack. These cannot be intercepted without also intercepting XSAVE which
would likely cause unacceptable performance overhead.
MSR_IA32_INT_SSP_TAB is not managed by XSAVE, so it is intercepted.
Reviewed-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: John Allen <john.allen@amd.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-39-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add shadow stack VMCB fields to dump_vmcb. PL0_SSP, PL1_SSP, PL2_SSP,
PL3_SSP, and U_CET are part of the SEV-ES save area and are encrypted,
but can be decrypted and dumped if the guest policy allows debugging.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: John Allen <john.allen@amd.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-38-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Transfer the three CET Shadow Stack VMCB fields (S_CET, ISST_ADDR, and
SSP) on VMRUN, #VMEXIT, and loading nested state (saving nested state
simply copies the entire save area). SVM doesn't provide a way to
disallow L1 from enabling Shadow Stacks for L2, i.e. KVM *must* provide
nested support before advertising SHSTK to userspace.
Link: https://lore.kernel.org/r/20250919223258.1604852-37-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Emulate shadow stack MSR access by reading and writing to the
corresponding fields in the VMCB.
Signed-off-by: John Allen <john.allen@amd.com>
[sean: mark VMCB_CET dirty/clean as appropriate]
Link: https://lore.kernel.org/r/20250919223258.1604852-36-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Advertise the LOAD_CET_STATE VM-Entry/Exit control bits in the nested VMX
MSRS, as all nested support for CET virtualization, including consistency
checks, is in place.
Advertise support if and only if KVM supports at least one of IBT or SHSTK.
While it's userspace's responsibility to provide a consistent CPU model to
the guest, that doesn't mean KVM should set userspace up to fail.
Note, the existing {CLEAR,LOAD}_BNDCFGS behavior predates
KVM_X86_QUIRK_STUFF_FEATURE_MSRS, i.e. KVM "solved" the inconsistent CPU
model problem by overwriting the VMX MSRs provided by userspace.
Signed-off-by: Chao Gao <chao.gao@intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-35-seanjc@google.com
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Introduce consistency checks for CET states during nested VM-entry.
A VMCS contains both guest and host CET states, each comprising the
IA32_S_CET MSR, SSP, and IA32_INTERRUPT_SSP_TABLE_ADDR MSR. Various
checks are applied to CET states during VM-entry as documented in SDM
Vol3 Chapter "VM ENTRIES". Implement all these checks during nested
VM-entry to emulate the architectural behavior.
In summary, there are three kinds of checks on guest/host CET states
during VM-entry:
A. Checks applied to both guest states and host states:
* The IA32_S_CET field must not set any reserved bits; bits 10 (SUPPRESS)
and 11 (TRACKER) cannot both be set.
* SSP should not have bits 1:0 set.
* The IA32_INTERRUPT_SSP_TABLE_ADDR field must be canonical.
B. Checks applied to host states only
* IA32_S_CET MSR and SSP must be canonical if the CPU enters 64-bit mode
after VM-exit. Otherwise, IA32_S_CET and SSP must have their higher 32
bits cleared.
C. Checks applied to guest states only:
* IA32_S_CET MSR and SSP are not required to be canonical (i.e., 63:N-1
are identical, where N is the CPU's maximum linear-address width). But,
bits 63:N of SSP must be identical.
Tested-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-34-seanjc@google.com
[sean: have common helper return 0/-EINVAL, not true/false]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add consistency checks for CR4.CET and CR0.WP in guest-state or host-state
area in the VMCS12. This ensures that configurations with CR4.CET set and
CR0.WP not set result in VM-entry failure, aligning with architectural
behavior.
Tested-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-33-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Set up CET MSRs, related VM_ENTRY/EXIT control bits and fixed CR4 setting
to enable CET for nested VM.
vmcs12 and vmcs02 needs to be synced when L2 exits to L1 or when L1 wants
to resume L2, that way correct CET states can be observed by one another.
Please note that consistency checks regarding CET state during VM-Entry
will be added later to prevent this patch from becoming too large.
Advertising the new CET VM_ENTRY/EXIT control bits are also be deferred
until after the consistency checks are added.
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Tested-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Xin Li (Intel) <xin@zytor.com>
Tested-by: Xin Li (Intel) <xin@zytor.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-32-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Per SDM description(Vol.3D, Appendix A.1):
"If bit 56 is read as 1, software can use VM entry to deliver a hardware
exception with or without an error code, regardless of vector"
Modify has_error_code check before inject events to nested guest. Only
enforce the check when guest is in real mode, the exception is not hard
exception and the platform doesn't enumerate bit56 in VMX_BASIC, in all
other case ignore the check to make the logic consistent with SDM.
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Tested-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-31-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Swap the order between configuring nested VMX capabilities and base CPU
capabilities, so that nested VMX support can be conditioned on core KVM
support, e.g. to allow conditioning support for LOAD_CET_STATE on the
presence of IBT or SHSTK. Because the sanity checks on nested VMX config
performed by vmx_check_processor_compat() run _after_ vmx_hardware_setup(),
any use of kvm_cpu_cap_has() when configuring nested VMX support will lead
to failures in vmx_check_processor_compat().
While swapping the order of two (or more) configuration flows can lead to
a game of whack-a-mole, in this case nested support inarguably should be
done after base support. KVM should never condition base support on nested
support, because nested support is fully optional, while obviously it's
desirable to condition nested support on base support. And there's zero
evidence the current ordering was intentional, e.g. commit 66a6950f99
("KVM: x86: Introduce kvm_cpu_caps to replace runtime CPUID masking")
likely placed the call to kvm_set_cpu_caps() after nested setup because it
looked pretty.
Reviewed-by: Chao Gao <chao.gao@intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-30-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add support for the LOAD_CET_STATE VM-Enter and VM-Exit controls, the
CET XFEATURE bits in XSS, and advertise support for IBT and SHSTK to
userspace. Explicitly clear IBT and SHSTK onn SVM, as additional work is
needed to enable CET on SVM, e.g. to context switch S_CET and other state.
Disable KVM CET feature if unrestricted_guest is unsupported/disabled as
KVM does not support emulating CET, as running without Unrestricted Guest
can result in KVM emulating large swaths of guest code. While it's highly
unlikely any guest will trigger emulation while also utilizing IBT or
SHSTK, there's zero reason to allow CET without Unrestricted Guest as that
combination should only be possible when explicitly disabling
unrestricted_guest for testing purposes.
Disable CET if VMX_BASIC[bit56] == 0, i.e. if hardware strictly enforces
the presence of an Error Code based on exception vector, as attempting to
inject a #CP with an Error Code (#CP architecturally has an Error Code)
will fail due to the #CP vector historically not having an Error Code.
Clear S_CET and SSP-related VMCS on "reset" to emulate the architectural
of CET MSRs and SSP being reset to 0 after RESET, power-up and INIT. Note,
KVM already clears guest CET state that is managed via XSTATE in
kvm_xstate_reset().
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
[sean: move some bits to separate patches, massage changelog]
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-29-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
