Linux guests since commit b1c3497e ("x86/xen: Add support for
HVMOP_set_evtchn_upcall_vector") in v6.0 onwards will use the per-vCPU
upcall vector when it's advertised in the Xen CPUID leaves.

This upcall is injected through the guest's local APIC as an MSI, unlike
the older system vector which was merely injected by the hypervisor any
time the CPU was able to receive an interrupt and the upcall_pending
flags is set in its vcpu_info.

Effectively, that makes the per-CPU upcall edge triggered instead of
level triggered, which results in the upcall being lost if the MSI is
delivered when the local APIC is *disabled*.

Xen checks the vcpu_info->evtchn_upcall_pending flag when the local APIC
for a vCPU is software enabled (in fact, on any write to the SPIV
register which doesn't disable the APIC). Do the same in KVM since KVM
doesn't provide a way for userspace to intervene and trap accesses to
the SPIV register of a local APIC emulated by KVM.

Fixes: fde0451b ("KVM: x86/xen: Support per-vCPU event channel upcall via local APIC")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240227115648.3104-3-dwmw2@infradead.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

A test program such as http://david.woodhou.se/timerlat.c confirms user
reports that timers are increasingly inaccurate as the lifetime of a
guest increases. Reporting the actual delay observed when asking for
100µs of sleep, it starts off OK on a newly-launched guest but gets
worse over time, giving incorrect sleep times:

root@ip-10-0-193-21:~# ./timerlat -c -n 5
00000000 latency 103243/100000 (3.2430%)
00000001 latency 103243/100000 (3.2430%)
00000002 latency 103242/100000 (3.2420%)
00000003 latency 103245/100000 (3.2450%)
00000004 latency 103245/100000 (3.2450%)

The biggest problem is that get_kvmclock_ns() returns inaccurate values
when the guest TSC is scaled. The guest sees a TSC value scaled from the
host TSC by a mul/shift conversion (hopefully done in hardware). The
guest then converts that guest TSC value into nanoseconds using the
mul/shift conversion given to it by the KVM pvclock information.

But get_kvmclock_ns() performs only a single conversion directly from
host TSC to nanoseconds, giving a different result. A test program at
http://david.woodhou.se/tsdrift.c demonstrates the cumulative error
over a day.

It's non-trivial to fix get_kvmclock_ns(), although I'll come back to
that. The actual guest hv_clock is per-CPU, and *theoretically* each
vCPU could be running at a *different* frequency. But this patch is
needed anyway because...

The other issue with Xen timers was that the code would snapshot the
host CLOCK_MONOTONIC at some point in time, and then... after a few
interrupts may have occurred, some preemption perhaps... would also read
the guest's kvmclock. Then it would proceed under the false assumption
that those two happened at the *same* time. Any time which *actually*
elapsed between reading the two clocks was introduced as inaccuracies
in the time at which the timer fired.

Fix it to use a variant of kvm_get_time_and_clockread(), which reads the
host TSC just *once*, then use the returned TSC value to calculate the
kvmclock (making sure to do that the way the guest would instead of
making the same mistake get_kvmclock_ns() does).

Sadly, hrtimers based on CLOCK_MONOTONIC_RAW are not supported, so Xen
timers still have to use CLOCK_MONOTONIC. In practice the difference
between the two won't matter over the timescales involved, as the
*absolute* values don't matter; just the delta.

This does mean a new variant of kvm_get_time_and_clockread() is needed;
called kvm_get_monotonic_and_clockread() because that's what it does.

Fixes: 53639526 ("KVM: x86/xen: handle PV timers oneshot mode")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Link: https://lore.kernel.org/r/20240227115648.3104-2-dwmw2@infradead.org
[sean: massage moved comment, tweak if statement formatting]
Signed-off-by: Sean Christopherson <seanjc@google.com>

If the guest sets an explicit vcpu_info GPA then, for any of the first 32
vCPUs, the content of the default vcpu_info in the shared_info page must be
copied into the new location. Because this copy may race with event
delivery (which updates the 'evtchn_pending_sel' field in vcpu_info),
event delivery needs to be deferred until the copy is complete.

Happily there is already a shadow of 'evtchn_pending_sel' in kvm_vcpu_xen
that is used in atomic context if the vcpu_info PFN cache has been
invalidated so that the update of vcpu_info can be deferred until the
cache can be refreshed (on vCPU thread's the way back into guest context).

Use this shadow if the vcpu_info cache has been *deactivated*, so that
the VMM can safely copy the vcpu_info content and then re-activate the
cache with the new GPA. To do this, stop considering an inactive vcpu_info
cache as a hard error in kvm_xen_set_evtchn_fast(), and let the existing
kvm_gpc_check() fail and kick the vCPU (if necessary).
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-21-paul@xen.org
[sean: add a bit of verbosity to the changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

When processing mmu_notifier invalidations for gpc caches, pre-check for
overlap with the invalidation event while holding gpc->lock for read, and
only take gpc->lock for write if the cache needs to be invalidated.  Doing
a pre-check without taking gpc->lock for write avoids unnecessarily
contending the lock for unrelated invalidations, which is very beneficial
for caches that are heavily used (but rarely subjected to mmu_notifier
invalidations).
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-20-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

Now that all relevant kernel changes and selftests are in place, enable the
new capability.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-17-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

If the relevant capability (KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA) is present
then re-map vcpu_info using the HVA part way through the tests to make sure
then there is no functional change.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-16-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

Using the HVA of the shared_info page is more efficient, so if the
capability (KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA) is present use that method
to do the mapping.

NOTE: Have the juggle_shinfo_state() thread map and unmap using both
      GFN and HVA, to make sure the older mechanism is not broken.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-15-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

If the guest does not explicitly set the GPA of vcpu_info structure in
memory then, for guests with 32 vCPUs or fewer, the vcpu_info embedded
in the shared_info page may be used. As described in a previous commit,
the shared_info page is an overlay at a fixed HVA within the VMM, so in
this case it also more optimal to activate the vcpu_info cache with a
fixed HVA to avoid unnecessary invalidation if the guest memory layout
is modified.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-14-paul@xen.org
[sean: use kvm_gpc_is_{gpa,hva}_active()]
Signed-off-by: Sean Christopherson <seanjc@google.com>

The shared_info page is not guest memory as such. It is a dedicated page
allocated by the VMM and overlaid onto guest memory in a GFN chosen by the
guest and specified in the XENMEM_add_to_physmap hypercall. The guest may
even request that shared_info be moved from one GFN to another by
re-issuing that hypercall, but the HVA is never going to change.

Because the shared_info page is an overlay the memory slots need to be
updated in response to the hypercall. However, memory slot adjustment is
not atomic and, whilst all vCPUs are paused, there is still the possibility
that events may be delivered (which requires the shared_info page to be
updated) whilst the shared_info GPA is absent. The HVA is never absent
though, so it makes much more sense to use that as the basis for the
kernel's mapping.

Hence add a new KVM_XEN_ATTR_TYPE_SHARED_INFO_HVA attribute type for this
purpose and a KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA flag to advertize its
availability. Don't actually advertize it yet though. That will be done in
a subsequent patch, which will also add tests for the new attribute type.

Also update the KVM API documentation with the new attribute and also fix
it up to consistently refer to 'shared_info' (with the underscore).
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-13-paul@xen.org
[sean: store "hva" as a user pointer, use kvm_gpc_is_{gpa,hva}_active()]
Signed-off-by: Sean Christopherson <seanjc@google.com>

If the shared_info PFN cache has already been initialized then the content
of the shared_info page needs to be re-initialized whenever the guest
mode is (re)set.
Setting the guest mode is either done explicitly by the VMM via the
KVM_XEN_ATTR_TYPE_LONG_MODE attribute, or implicitly when the guest writes
the MSR to set up the hypercall page.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-12-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

A subsequent patch will allow shared_info to be initialized using either a
GPA or a user-space (i.e. VMM) HVA. To make that patch cleaner, separate
the initialization of the shared_info content from the activation of the
pfncache.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-11-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

Some pfncache pages may actually be overlays on guest memory that have a
fixed HVA within the VMM. It's pointless to invalidate such cached
mappings if the overlay is moved so allow a cache to be activated directly
with the HVA to cater for such cases. A subsequent patch will make use
of this facility.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-10-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

Rename kvm_is_error_gpa() to kvm_is_gpa_in_memslot() and invert the
polarity accordingly in order to (a) free up kvm_is_error_gpa() to match
with kvm_is_error_{hva,page}(), and (b) to make it more obvious that the
helper is doing a memslot lookup, i.e. not simply checking for INVALID_GPA.

No functional change intended.

Link: https://lore.kernel.org/r/20240215152916.1158-9-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

Currently the pfncache page offset is sometimes determined using the gpa
and sometimes the khva, whilst the uhva is always page-aligned. After a
subsequent patch is applied the gpa will not always be valid so adjust
the code to include the page offset in the uhva and use it consistently
as the source of truth.

Also, where a page-aligned address is required, use PAGE_ALIGN_DOWN()
for clarity.

No functional change intended.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-8-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

Some code in pfncache uses offset_in_page() but in other places it is open-
coded. Use offset_in_page() consistently everywhere.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-7-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

As noted in [1] the KVM_GUEST_USES_PFN usage flag is never set by any
callers of kvm_gpc_init(), and for good reason: the implementation is
incomplete/broken.  And it's not clear that there will ever be a user of
KVM_GUEST_USES_PFN, as coordinating vCPUs with mmu_notifier events is
non-trivial.

Remove KVM_GUEST_USES_PFN and all related code, e.g. dropping
KVM_GUEST_USES_PFN also makes the 'vcpu' argument redundant, to avoid
having to reason about broken code as __kvm_gpc_refresh() evolves.

Moreover, all existing callers specify KVM_HOST_USES_PFN so the usage
check in hva_to_pfn_retry() and hence the 'usage' argument to
kvm_gpc_init() are also redundant.

[1] https://lore.kernel.org/all/ZQiR8IpqOZrOpzHC@google.comSigned-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-6-paul@xen.org
[sean: explicitly call out that guest usage is incomplete]
Signed-off-by: Sean Christopherson <seanjc@google.com>

At the moment pages are marked dirty by open-coded calls to
mark_page_dirty_in_slot(), directly deferefencing the gpa and memslot
from the cache. After a subsequent patch these may not always be set
so add a helper now so that caller will protected from the need to know
about this detail.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-5-paul@xen.org
[sean: decrease indentation, use gpa_to_gfn()]
Signed-off-by: Sean Christopherson <seanjc@google.com>

Sampling gpa and memslot from an unlocked pfncache may yield inconsistent
values so, since there is no problem with calling mark_page_dirty_in_slot()
with the pfncache lock held, relocate the calls in
kvm_xen_update_runstate_guest() and kvm_xen_inject_pending_events()
accordingly.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-4-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

There is no need for the existing kvm_gpc_XXX() functions to be exported.
Clean up now before additional functions are added in subsequent patches.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-3-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

There is a pfncache unmap helper but mapping is open-coded. Arguably this
is fine because mapping is done in only one place, hva_to_pfn_retry(), but
adding the helper does make that function more readable.

No functional change intended.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-2-paul@xen.orgSigned-off-by: Sean Christopherson <seanjc@google.com>

KVM_CAP_IRQ_ROUTING is always defined, so there is no need to check if it is.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Since all architectures (for historical reasons) have to define
struct kvm_guest_debug_arch, and since userspace has to check
KVM_CHECK_EXTENSION(KVM_CAP_SET_GUEST_DEBUG) anyway, there is
no advantage in masking the capability #define itself.  Remove
the #define __KVM_HAVE_GUEST_DEBUG from architecture-specific
headers.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM uses __KVM_HAVE_* symbols in the architecture-dependent uapi/asm/kvm.h to mask
unused definitions in include/uapi/linux/kvm.h.  __KVM_HAVE_READONLY_MEM however
was nothing but a misguided attempt to define KVM_CAP_READONLY_MEM only on
architectures where KVM_CHECK_EXTENSION(KVM_CAP_READONLY_MEM) could possibly
return nonzero.  This however does not make sense, and it prevented userspace
from supporting this architecture-independent feature without recompilation.

Therefore, these days __KVM_HAVE_READONLY_MEM does not mask anything and
is only used in virt/kvm/kvm_main.c.  Userspace does not need to test it
and there should be no need for it to exist.  Remove it and replace it
with a Kconfig symbol within Linux source code.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

While this in principle breaks userspace code that mentions KVM_ARM_DEV_*
on architectures other than aarch64, this seems unlikely to be
a problem considering that run->s.regs.device_irq_level is only
defined on that architecture.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

While this in principle breaks the appearance of KVM_S390_* ioctls on architectures
other than s390, this seems unlikely to be a problem considering that there are
already many "struct kvm_s390_*" definitions in arch/s390/include/uapi.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

While this in principle breaks the appearance of KVM_PPC_* ioctls on architectures
other than powerpc, this seems unlikely to be a problem considering that there are
already many "struct kvm_ppc_*" definitions in arch/powerpc/include/uapi.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Several capabilities that exist only on x86 nevertheless have their
structs defined in include/uapi/linux/kvm.h.  Move them to
arch/x86/include/uapi/asm/kvm.h for cleanliness.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Change uapi header uses of GENMASK to instead use the uapi/linux/bits.h bit
macros, since GENMASK is not defined in uapi headers.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Change uapi header uses of BIT to instead use the uapi/linux/const.h bit
macros, since BIT is not defined in uapi headers.

The PMU mask uses _BITUL since it targets a 32 bit flag field, whereas
the longmode definition is meant for a 64 bit flag field.

Cc: Sean Christophersen <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
Message-Id: <20231207001142.3617856-1-dionnaglaze@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Move __GENMASK and __GENMASK_ULL from include/ to include/uapi/ so that they can
be used to define masks in userspace API headers.  Compared to what is already
in include/linux/bits.h, the definitions need to use the uglified versions of
UL(), ULL(), BITS_PER_LONG and BITS_PER_LONG_LONG (which did not even exist),
but otherwise expand to the same content.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Pull crypto fixes from Herbert Xu:
 "Fix regressions in cbc and algif_hash, as well as an older
  NULL-pointer dereference in ccp"

* tag 'v6.8-p3' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: algif_hash - Remove bogus SGL free on zero-length error path
  crypto: cbc - Ensure statesize is zero
  crypto: ccp - Fix null pointer dereference in __sev_platform_shutdown_locked

Pull percpu fix from Dennis Zhou:

 - fix riscv wrong size passed to local_flush_tlb_range_asid()

* tag 'percpu-for-6.8-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu:
  riscv: Fix wrong size passed to local_flush_tlb_range_asid()

Merge tag 'loongarch-fixes-6.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson

Pull LoongArch fixes from Huacai Chen:
 "Fix acpi_core_pic[] array overflow, fix earlycon parameter if KASAN
  enabled, disable UBSAN instrumentation for vDSO build, and two Kconfig
  cleanups"

* tag 'loongarch-fixes-6.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson:
  LoongArch: vDSO: Disable UBSAN instrumentation
  LoongArch: Fix earlycon parameter if KASAN enabled
  LoongArch: Change acpi_core_pic[NR_CPUS] to acpi_core_pic[MAX_CORE_PIC]
  LoongArch: Select HAVE_ARCH_SECCOMP to use the common SECCOMP menu
  LoongArch: Select ARCH_ENABLE_THP_MIGRATION instead of redefining it

Pull kvm fixes from Paolo Bonzini:
 "x86 guest:

   - Avoid false positive for check that only matters on AMD processors

  x86:

   - Give a hint when Win2016 might fail to boot due to XSAVES &&
     !XSAVEC configuration

   - Do not allow creating an in-kernel PIT unless an IOAPIC already
     exists

  RISC-V:

   - Allow ISA extensions that were enabled for bare metal in 6.8 (Zbc,
     scalar and vector crypto, Zfh[min], Zihintntl, Zvfh[min], Zfa)

  S390:

   - fix CC for successful PQAP instruction

   - fix a race when creating a shadow page"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  x86/coco: Define cc_vendor without CONFIG_ARCH_HAS_CC_PLATFORM
  x86/kvm: Fix SEV check in sev_map_percpu_data()
  KVM: x86: Give a hint when Win2016 might fail to boot due to XSAVES erratum
  KVM: x86: Check irqchip mode before create PIT
  KVM: riscv: selftests: Add Zfa extension to get-reg-list test
  RISC-V: KVM: Allow Zfa extension for Guest/VM
  KVM: riscv: selftests: Add Zvfh[min] extensions to get-reg-list test
  RISC-V: KVM: Allow Zvfh[min] extensions for Guest/VM
  KVM: riscv: selftests: Add Zihintntl extension to get-reg-list test
  RISC-V: KVM: Allow Zihintntl extension for Guest/VM
  KVM: riscv: selftests: Add Zfh[min] extensions to get-reg-list test
  RISC-V: KVM: Allow Zfh[min] extensions for Guest/VM
  KVM: riscv: selftests: Add vector crypto extensions to get-reg-list test
  RISC-V: KVM: Allow vector crypto extensions for Guest/VM
  KVM: riscv: selftests: Add scaler crypto extensions to get-reg-list test
  RISC-V: KVM: Allow scalar crypto extensions for Guest/VM
  KVM: riscv: selftests: Add Zbc extension to get-reg-list test
  RISC-V: KVM: Allow Zbc extension for Guest/VM
  KVM: s390: fix cc for successful PQAP
  KVM: s390: vsie: fix race during shadow creation

Pull nfsd fix from Chuck Lever:

 - Address a deadlock regression in RELEASE_LOCKOWNER

* tag 'nfsd-6.8-3' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
  nfsd: don't take fi_lock in nfsd_break_deleg_cb()

Pull btrfs fixes from David Sterba:

 - two fixes preventing deletion and manual creation of subvolume qgroup

 - unify error code returned for unknown send flags

 - fix assertion during subvolume creation when anonymous device could
   be allocated by other thread (e.g. due to backref walk)

* tag 'for-6.8-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: do not ASSERT() if the newly created subvolume already got read
  btrfs: forbid deleting live subvol qgroup
  btrfs: forbid creating subvol qgroups
  btrfs: send: return EOPNOTSUPP on unknown flags

After commit a9ef2774 ("x86/kvm: Fix SEV check in
sev_map_percpu_data()"), there is a build error when building
x86_64_defconfig with GCOV using LLVM:

  ld.lld: error: undefined symbol: cc_vendor
  >>> referenced by kvm.c
  >>>               arch/x86/kernel/kvm.o:(kvm_smp_prepare_boot_cpu) in archive vmlinux.a

which corresponds to

  if (cc_vendor != CC_VENDOR_AMD ||
      !cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
            return;

Without GCOV, clang is able to eliminate the use of cc_vendor because
cc_platform_has() evaluates to false when CONFIG_ARCH_HAS_CC_PLATFORM is
not set, meaning that if statement will be true no matter what value
cc_vendor has.

With GCOV, the instrumentation keeps the use of cc_vendor around for
code coverage purposes but cc_vendor is only declared, not defined,
without CONFIG_ARCH_HAS_CC_PLATFORM, leading to the build error above.

Provide a macro definition of cc_vendor when CONFIG_ARCH_HAS_CC_PLATFORM
is not set with a value of CC_VENDOR_NONE, so that the first condition
can always be evaluated/eliminated at compile time, avoiding the build
error altogether. This is very similar to the situation prior to
commit da86eb96 ("x86/coco: Get rid of accessor functions").
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Message-Id: <20240202-provide-cc_vendor-without-arch_has_cc_platform-v1-1-09ad5f2a3099@kernel.org>
Fixes: a9ef2774 ("x86/kvm: Fix SEV check in sev_map_percpu_data()", 2024-01-31)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Pull bcachefs fixes from Kent Overstreet:
 "Two serious ones here that we'll want to backport to stable: a fix for
  a race in the thread_with_file code, and another locking fixup in the
  subvolume deletion path"

* tag 'bcachefs-2024-02-05' of https://evilpiepirate.org/git/bcachefs:
  bcachefs: time_stats: Check for last_event == 0 when updating freq stats
  bcachefs: install fd later to avoid race with close
  bcachefs: unlock parent dir if entry is not found in subvolume deletion
  bcachefs: Fix build on parisc by avoiding __multi3()

The vDSO executes in userspace, so the kernel's UBSAN should not
instrument it. Solves these kind of build errors:

  loongarch64-linux-ld: arch/loongarch/vdso/vgettimeofday.o: in function `vdso_shift_ns':
  lib/vdso/gettimeofday.c:23:(.text+0x3f8): undefined reference to `__ubsan_handle_shift_out_of_bounds'
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202401310530.lZHCj1Zl-lkp@intel.com/
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Fangrui Song <maskray@google.com>
Cc: loongarch@lists.linux.dev
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>