Some of the query information is already available via sysfs but
having a IOCTL makes the information easier to retrieve.
Signed-off-by: NJanosch Frank <frankja@linux.ibm.com>
Reviewed-by: NClaudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: NSteffen Eiden <seiden@linux.ibm.com>
Link: https://lore.kernel.org/r/20220517163629.3443-4-frankja@linux.ibm.com
Message-Id: <20220517163629.3443-4-frankja@linux.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@linux.ibm.com>

This commit fixes the transitional PCI device ID.

Fixes: d61914ea ("virtio: update virtio id table, add transitional ids")
Signed-off-by: NShunsuke Mie <mie@igel.co.jp>
Link: https://lore.kernel.org/r/20220510102723.87666-1-mie@igel.co.jpSigned-off-by: NMichael S. Tsirkin <mst@redhat.com>

The definition of RFKILL_IOCTL_MAX_SIZE introduced by commit
54f586a9 ("rfkill: make new event layout opt-in") is unusable
since it is based on RFKILL_IOC_EXT_SIZE which has not been defined.
Fix that by replacing the undefined constant with the constant which
is intended to be used in this definition.

Fixes: 54f586a9 ("rfkill: make new event layout opt-in")
Cc: stable@vger.kernel.org # 5.11+
Signed-off-by: NGleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: NDmitry V. Levin <ldv@altlinux.org>
Link: https://lore.kernel.org/r/20220506172454.120319-1-glebfm@altlinux.org
[add commit message provided later by Dmitry]
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>

ARM DEN0022D.b 5.19 "SYSTEM_SUSPEND" describes a PSCI call that allows
software to request that a system be placed in the deepest possible
low-power state. Effectively, software can use this to suspend itself to
RAM.

Unfortunately, there really is no good way to implement a system-wide
PSCI call in KVM. Any precondition checks done in the kernel will need
to be repeated by userspace since there is no good way to protect a
critical section that spans an exit to userspace. SYSTEM_RESET and
SYSTEM_OFF are equally plagued by this issue, although no users have
seemingly cared for the relatively long time these calls have been
supported.

The solution is to just make the whole implementation userspace's
problem. Introduce a new system event, KVM_SYSTEM_EVENT_SUSPEND, that
indicates to userspace a calling vCPU has invoked PSCI SYSTEM_SUSPEND.
Additionally, add a CAP to get buy-in from userspace for this new exit
type.

Only advertise the SYSTEM_SUSPEND PSCI call if userspace has opted in.
If a vCPU calls SYSTEM_SUSPEND, punt straight to userspace. Provide
explicit documentation of userspace's responsibilites for the exit and
point to the PSCI specification to describe the actual PSCI call.
Reviewed-by: NReiji Watanabe <reijiw@google.com>
Signed-off-by: NOliver Upton <oupton@google.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220504032446.4133305-8-oupton@google.com

Introduce a new MP state, KVM_MP_STATE_SUSPENDED, which indicates a vCPU
is in a suspended state. In the suspended state the vCPU will block
until a wakeup event (pending interrupt) is recognized.

Add a new system event type, KVM_SYSTEM_EVENT_WAKEUP, to indicate to
userspace that KVM has recognized one such wakeup event. It is the
responsibility of userspace to then make the vCPU runnable, or leave it
suspended until the next wakeup event.
Signed-off-by: NOliver Upton <oupton@google.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220504032446.4133305-7-oupton@google.com

When KVM_EXIT_SYSTEM_EVENT was introduced, it included a flags
member that at the time was unused.  Unfortunately this extensibility
mechanism has several issues:

- x86 is not writing the member, so it would not be possible to use it
  on x86 except for new events

- the member is not aligned to 64 bits, so the definition of the
  uAPI struct is incorrect for 32- on 64-bit userspace.  This is a
  problem for RISC-V, which supports CONFIG_KVM_COMPAT, but fortunately
  usage of flags was only introduced in 5.18.

Since padding has to be introduced, place a new field in there
that tells if the flags field is valid.  To allow further extensibility,
in fact, change flags to an array of 16 values, and store how many
of the values are valid.  The availability of the new ndata field
is tied to a system capability; all architectures are changed to
fill in the field.

To avoid breaking compilation of userspace that was using the flags
field, provide a userspace-only union to overlap flags with data[0].
The new field is placed at the same offset for both 32- and 64-bit
userspace.

Cc: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Peter Gonda <pgonda@google.com>
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reported-by: Nkernel test robot <lkp@intel.com>
Message-Id: <20220422103013.34832-1-pbonzini@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Unfortunately, the name/value choice for the MTE ELF segment type
(PT_ARM_MEMTAG_MTE) was pretty poor: LOPROC+1 is already in use by
PT_AARCH64_UNWIND, as defined in the AArch64 ELF ABI
(https://github.com/ARM-software/abi-aa/blob/main/aaelf64/aaelf64.rst).

Update the ELF segment type value to LOPROC+2 and also change the define
to PT_AARCH64_MEMTAG_MTE to match the AArch64 ELF ABI namespace. The
AArch64 ELF ABI document is updating accordingly (segment type not
previously mentioned in the document).
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Fixes: 761b9b36 ("elf: Introduce the ARM MTE ELF segment type")
Cc: Will Deacon <will@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luis Machado <luis.machado@arm.com>
Cc: Richard Earnshaw <Richard.Earnshaw@arm.com>
Link: https://lore.kernel.org/r/20220425151833.2603830-1-catalin.marinas@arm.comSigned-off-by: NWill Deacon <will@kernel.org>

The ZA array can be read and written with the NT_ARM_ZA.  Similarly to
our interface for the SVE vector registers the regset consists of a
header with information on the current vector length followed by an
optional register data payload, represented as for signals as a series
of horizontal vectors from 0 to VL/8 in the endianness independent
format used for vectors.

On get if ZA is enabled then register data will be provided, otherwise
it will be omitted.  On set if register data is provided then ZA is
enabled and initialized using the provided data, otherwise it is
disabled.
Signed-off-by: NMark Brown <broonie@kernel.org>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220419112247.711548-22-broonie@kernel.orgSigned-off-by: NCatalin Marinas <catalin.marinas@arm.com>

The streaming mode SVE registers are represented using the same data
structures as for SVE but since the vector lengths supported and in use
may not be the same as SVE we represent them with a new type NT_ARM_SSVE.
Unfortunately we only have a single 16 bit reserved field available in
the header so there is no space to fit the current and maximum vector
length for both standard and streaming SVE mode without redefining the
structure in a way the creates a complicatd and fragile ABI. Since FFR
is not present in streaming mode it is read and written as zero.

Setting NT_ARM_SSVE registers will put the task into streaming mode,
similarly setting NT_ARM_SVE registers will exit it. Reads that do not
correspond to the current mode of the task will return the header with
no register data. For compatibility reasons on write setting no flag for
the register type will be interpreted as setting SVE registers, though
users can provide no register data as an alternative mechanism for doing
so.
Signed-off-by: NMark Brown <broonie@kernel.org>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220419112247.711548-21-broonie@kernel.orgSigned-off-by: NCatalin Marinas <catalin.marinas@arm.com>

As for SVE provide a prctl() interface which allows processes to
configure their SME vector length.
Signed-off-by: NMark Brown <broonie@kernel.org>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220419112247.711548-12-broonie@kernel.orgSigned-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Add keycodes that are used by marine navigation devices.
Signed-off-by: NShelby Heffron <Shelby.Heffron@garmin.com>
Link: https://lore.kernel.org/r/20220414015356.1619310-1-Shelby.Heffron@garmin.comSigned-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

If an SEV-ES guest requests termination, exit to userspace with
KVM_EXIT_SYSTEM_EVENT and a dedicated SEV_TERM type instead of -EINVAL
so that userspace can take appropriate action.

See AMD's GHCB spec section '4.1.13 Termination Request' for more details.
Suggested-by: NSean Christopherson <seanjc@google.com>
Suggested-by: NPaolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NPeter Gonda <pgonda@google.com>
Reported-by: Nkernel test robot <lkp@intel.com>
Message-Id: <20220407210233.782250-1-pgonda@google.com>
[Add documentatino. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Give applications a way to tell if the kernel supports sane linked files,
as in files being assigned at the right time to be able to reliably
do <open file direct into slot X><read file from slot X> while using
IOSQE_IO_LINK to order them.

Not really a bug fix, but flag it as such so that it gets pulled in with
backports of the deferred file assignment.

Fixes: 6bf9c47a ("io_uring: defer file assignment")
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Fix a misspelling of "palette" in a comment.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: NPekka Paalanen <pekka.paalanen@collabora.com>
Signed-off-by: NHelge Deller <deller@gmx.de>

After being merged, user_events become more visible to a wider audience
that have concerns with the current API.

It is too late to fix this for this release, but instead of a full
revert, just mark it as BROKEN (which prevents it from being selected in
make config).  Then we can work finding a better API.  If that fails,
then it will need to be completely reverted.

To not have the code silently bitrot, still allow building it with
COMPILE_TEST.

And to prevent the uapi header from being installed, then later changed,
and then have an old distro user space see the old version, move the
header file out of the uapi directory.

Surround the include with CONFIG_COMPILE_TEST to the current location,
but when the BROKEN tag is taken off, it will use the uapi directory,
and fail to compile.  This is a good way to remind us to move the header
back.

Link: https://lore.kernel.org/all/20220330155835.5e1f6669@gandalf.local.home
Link: https://lkml.kernel.org/r/20220330201755.29319-1-mathieu.desnoyers@efficios.comSuggested-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: NSteven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

While user_events API is under development and has been marked for broken
to not let the API become fixed, move the header file out of the uapi
directory. This is to prevent it from being installed, then later changed,
and then have an old distro user space update with a new kernel, where
applications see the user_events being available, but the old header is in
place, and then they get compiled incorrectly.

Also, surround the include with CONFIG_COMPILE_TEST to the current
location, but when the BROKEN tag is taken off, it will use the uapi
directory, and fail to compile. This is a good way to remind us to move
the header back.

Link: https://lore.kernel.org/all/20220330155835.5e1f6669@gandalf.local.home
Link: https://lkml.kernel.org/r/20220330201755.29319-1-mathieu.desnoyers@efficios.com
Link: https://lkml.kernel.org/r/20220401143903.188384f3@gandalf.local.homeSuggested-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: NSteven Rostedt (Google) <rostedt@goodmis.org>

Remove eBPF interfaces within user_events to ensure they are fully
reviewed.

Link: https://lore.kernel.org/all/20220329165718.GA10381@kbox/
Link: https://lkml.kernel.org/r/20220329173051.10087-1-beaub@linux.microsoft.comSuggested-by: NAlexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: NBeau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: NSteven Rostedt (Google) <rostedt@goodmis.org>

This sets the default TSC frequency for subsequently created vCPUs.
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20220225145304.36166-2-dwmw2@infradead.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

At the end of the patch series adding this batch of event channel
acceleration features, finally add the feature bit which advertises
them and document it all.

For SCHEDOP_poll we need to wake a polling vCPU when a given port
is triggered, even when it's masked — and we want to implement that
in the kernel, for efficiency. So we want the kernel to know that it
has sole ownership of event channel delivery. Thus, we allow
userspace to make the 'promise' by setting the corresponding feature
bit in its KVM_XEN_HVM_CONFIG call. As we implement SCHEDOP_poll
bypass later, we will do so only if that promise has been made by
userspace.
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-16-dwmw2@infradead.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Windows uses a per-vCPU vector, and it's delivered via the local APIC
basically like an MSI (with associated EOI) unlike the traditional
guest-wide vector which is just magically asserted by Xen (and in the
KVM case by kvm_xen_has_interrupt() / kvm_cpu_get_extint()).

Now that the kernel is able to raise event channel events for itself,
being able to do so for Windows guests is also going to be useful.
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-15-dwmw2@infradead.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Turns out this is a fast path for PV guests because they use it to
trigger the event channel upcall. So letting it bounce all the way up
to userspace is not great.
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-14-dwmw2@infradead.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

If the guest has offloaded the timer virq, handle the following
hypercalls for programming the timer:

    VCPUOP_set_singleshot_timer
    VCPUOP_stop_singleshot_timer
    set_timer_op(timestamp_ns)

The event channel corresponding to the timer virq is then used to inject
events once timer deadlines are met. For now we back the PV timer with
hrtimer.

[ dwmw2: Add save/restore, 32-bit compat mode, immediate delivery,
         don't check timer in kvm_vcpu_has_event() ]
Signed-off-by: NJoao Martins <joao.m.martins@oracle.com>
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-13-dwmw2@infradead.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

In order to intercept hypercalls such as VCPUOP_set_singleshot_timer, we
need to be aware of the Xen CPU numbering.

This looks a lot like the Hyper-V handling of vpidx, for obvious reasons.
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-12-dwmw2@infradead.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Userspace registers a sending @port to either deliver to an @eventfd
or directly back to a local event channel port.

After binding events the guest or host may wish to bind those
events to a particular vcpu. This is usually done for unbound
and and interdomain events. Update requests are handled via the
KVM_XEN_EVTCHN_UPDATE flag.

Unregistered ports are handled by the emulator.
Co-developed-by: NAnkur Arora <ankur.a.arora@oracle.com>
Co-developed-By: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NJoao Martins <joao.m.martins@oracle.com>
Signed-off-by: NAnkur Arora <ankur.a.arora@oracle.com>
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-10-dwmw2@infradead.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This adds a KVM_XEN_HVM_EVTCHN_SEND ioctl which allows direct injection
of events given an explicit { vcpu, port, priority } in precisely the
same form that those fields are given in the IRQ routing table.

Userspace is currently able to inject 2-level events purely by setting
the bits in the shared_info and vcpu_info, but FIFO event channels are
harder to deal with; we will need the kernel to take sole ownership of
delivery when we support those.

A patch advertising this feature with a new bit in the KVM_CAP_XEN_HVM
ioctl will be added in a subsequent patch.
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-9-dwmw2@infradead.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Add include guard wrapper define to uapi/linux/stddef.h to prevent macro
redefinition errors when stddef.h is included more than once. This was not
needed before since the only contents already used a redefinition test.
Signed-off-by: NTadeusz Struk <tadeusz.struk@linaro.org>
Link: https://lore.kernel.org/r/20220329171252.57279-1-tadeusz.struk@linaro.org
Fixes: 50d7bd38 ("stddef: Introduce struct_group() helper macro")
Cc: stable@vger.kernel.org
Signed-off-by: NKees Cook <keescook@chromium.org>

Support for cryptoloop was deleted in commit 47e96246 ("block:
remove support for cryptoloop and the xor transfer"), making the usage
of loop_info->lo_encrypt_type obsolete. However, this member was also
removed from the compat_loop_info definition and this breaks userspace
ioctl calls for 32-bit binaries and CONFIG_COMPAT=y.

This patch restores the compat_loop_info->lo_encrypt_type member and
marks it obsolete as well as in the uapi header definitions.

Fixes: 47e96246 ("block: remove support for cryptoloop and the xor transfer")
Signed-off-by: NCarlos Llamas <cmllamas@google.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220329201815.1347500-1-cmllamas@google.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

- GET_VQS_COUNT: the count of virtqueues that exposed
Signed-off-by: NLongpeng <longpeng2@huawei.com>
Link: https://lore.kernel.org/r/20220315032553.455-4-longpeng2@huawei.comSigned-off-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: Longpeng &lt;<a href="mailto:longpeng2@huawei.com" target="_blank">longpeng2@huawei.com</a>&gt;<br>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>

- GET_CONFIG_SIZE: return the size of the virtio config space.

The size contains the fields which are conditional on feature
bits.
Acked-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NLongpeng <longpeng2@huawei.com>
Link: https://lore.kernel.org/r/20220315032553.455-2-longpeng2@huawei.comSigned-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>

Introduce asymmetric service definition, asymmetric operations and
several well known algorithms.
Co-developed-by: Nlei he <helei.sig11@bytedance.com>
Signed-off-by: Nlei he <helei.sig11@bytedance.com>
Signed-off-by: Nzhenwei pi <pizhenwei@bytedance.com>
Link: https://lore.kernel.org/r/20220302033917.1295334-3-pizhenwei@bytedance.comSigned-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NGonglei <arei.gonglei@huawei.com>

Base on the lastest virtio crypto spec, define VIRTIO_CRYPTO_NOSPC.
Reviewed-by: NGonglei <arei.gonglei@huawei.com>
Signed-off-by: Nzhenwei pi <pizhenwei@bytedance.com>
Link: https://lore.kernel.org/r/20220302033917.1295334-2-pizhenwei@bytedance.comSigned-off-by: NMichael S. Tsirkin <mst@redhat.com>

This patch adds the definition of VIRTIO_F_IN_ORDER feature bit
in the relevant header file to make it available in QEMU's
linux standard header file virtio_config.h, which is updated using
scripts/update-linux-headers.sh
Signed-off-by: NGautam Dawar <gdawar@xilinx.com>
Link: https://lore.kernel.org/r/20220215053430.24650-1-gdawar@xilinx.comSigned-off-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NJason Wang <jasowang@redhat.com>

This was introduced with the message ring opcode, but isn't strictly
required for the request itself. The sender can encode what is needed
in user_data, which is passed to the receiver. It's unclear if having
a separate flag that essentially says "This CQE did not originate from
an SQE on this ring" provides any real utility to applications. While
we can always re-introduce a flag to provide this information, we cannot
take it away at a later point in time.

Remove the flag while we still can, before it's in a released kernel.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Several attributes depend on __CHECKER__, but previously there was no
clue in the tree about when __CHECKER__ might be defined.  Add hints at
the most common places (__kernel, __user, __iomem, __bitwise) and in the
sparse documentation.

Link: https://lkml.kernel.org/r/20220310220927.245704-3-helgaas@kernel.orgSigned-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: "Michael S . Tsirkin" <mst@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There are no users of "__bitwise__" except the definition of
"__bitwise".  Remove __bitwise__ and define __bitwise directly.

This is a follow-up to 05de9700 ("linux/types.h: enable endian
checks for all sparse builds").

[akpm@linux-foundation.org: change the tools/include/linux/types.h definition also]

Link: https://lkml.kernel.org/r/20220310220927.245704-2-helgaas@kernel.orgSigned-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Some RTCs have an IRQ pin that is not connected to a CPU interrupt but
rather directly to a PMIC or power supply. In that case, it is still useful
to be able to set alarms but we shouldn't expect interrupts.
Signed-off-by: NAlexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220309162301.61679-22-alexandre.belloni@bootlin.com

Userfaultfd is supposed to provide the full address (i.e., unmasked) of
the faulting access back to userspace.  However, that is not the case for
quite some time.

Even running "userfaultfd_demo" from the userfaultfd man page provides the
wrong output (and contradicts the man page).  Notice that
"UFFD_EVENT_PAGEFAULT event" shows the masked address (7fc5e30b3000) and
not the first read address (0x7fc5e30b300f).

	Address returned by mmap() = 0x7fc5e30b3000

	fault_handler_thread():
	    poll() returns: nready = 1; POLLIN = 1; POLLERR = 0
	    UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fc5e30b3000
		(uffdio_copy.copy returned 4096)
	Read address 0x7fc5e30b300f in main(): A
	Read address 0x7fc5e30b340f in main(): A
	Read address 0x7fc5e30b380f in main(): A
	Read address 0x7fc5e30b3c0f in main(): A

The exact address is useful for various reasons and specifically for
prefetching decisions.  If it is known that the memory is populated by
certain objects whose size is not page-aligned, then based on the faulting
address, the uffd-monitor can decide whether to prefetch and prefault the
adjacent page.

This bug has been for quite some time in the kernel: since commit
1a29d85e ("mm: use vmf->address instead of of vmf->virtual_address")
vmf->virtual_address"), which dates back to 2016.  A concern has been
raised that existing userspace application might rely on the old/wrong
behavior in which the address is masked.  Therefore, it was suggested to
provide the masked address unless the user explicitly asks for the exact
address.

Add a new userfaultfd feature UFFD_FEATURE_EXACT_ADDRESS to direct
userfaultfd to provide the exact address.  Add a new "real_address" field
to vmf to hold the unmasked address.  Provide the address to userspace
accordingly.

Initialize real_address in various code-paths to be consistent with
address, even when it is not used, to be on the safe side.

[namit@vmware.com: initialize real_address on all code paths, per Jan]
  Link: https://lkml.kernel.org/r/20220226022655.350562-1-namit@vmware.com
[akpm@linux-foundation.org: fix typo in comment, per Jan]

Link: https://lkml.kernel.org/r/20220218041003.3508-1-namit@vmware.comSigned-off-by: NNadav Amit <namit@vmware.com>
Acked-by: NPeter Xu <peterx@redhat.com>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Acked-by: NMike Rapoport <rppt@linux.ibm.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

KVM_CAP_DISABLE_QUIRKS is irrevocably broken. The capability does not
advertise the set of quirks which may be disabled to userspace, so it is
impossible to predict the behavior of KVM. Worse yet,
KVM_CAP_DISABLE_QUIRKS will tolerate any value for cap->args[0], meaning
it fails to reject attempts to set invalid quirk bits.

The only valid workaround for the quirky quirks API is to add a new CAP.
Actually advertise the set of quirks that can be disabled to userspace
so it can predict KVM's behavior. Reject values for cap->args[0] that
contain invalid bits.

Finally, add documentation for the new capability and describe the
existing quirks.
Signed-off-by: NOliver Upton <oupton@google.com>
Message-Id: <20220301060351.442881-5-oupton@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Let's say that the caller has storage for num_elem stack frames.  Then,
the BPF stack helper functions walk the stack for only num_elem frames.
This means that if skip > 0, one keeps only 'num_elem - skip' frames.

This is because it sets init_nr in the perf_callchain_entry to the end
of the buffer to save num_elem entries only.  I believe it was because
the perf callchain code unwound the stack frames until it reached the
global max size (sysctl_perf_event_max_stack).

However it now has perf_callchain_entry_ctx.max_stack to limit the
iteration locally.  This simplifies the code to handle init_nr in the
BPF callstack entries and removes the confusion with the perf_event's
__PERF_SAMPLE_CALLCHAIN_EARLY which sets init_nr to 0.

Also change the comment on bpf_get_stack() in the header file to be
more explicit what the return value means.

Fixes: c195651e ("bpf: add bpf_get_stack helper")
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/30a7b5d5-6726-1cc2-eaee-8da2828a9a9c@oracle.com
Link: https://lore.kernel.org/bpf/20220314182042.71025-1-namhyung@kernel.orgBased-on-patch-by: NEugene Loh <eugene.loh@oracle.com>

Today ptrace_message is easy to overlook as it not a core part of
ptrace_stop.  It has been overlooked so much that there are places
that set ptrace_message and don't clear it, and places that never set
it.  So if you get an unlucky sequence of events the ptracer may be
able to read a ptrace_message that does not apply to the current
ptrace stop.

Move setting of ptrace_message into ptrace_stop so that it always gets
set before the stop, and always gets cleared after the stop.  This
prevents non-sense from being reported to userspace and makes
ptrace_message more visible in the ptrace helper functions so that
kernel developers can see it.

Link: https://lkml.kernel.org/r/87bky67qfv.fsf_-_@email.froward.int.ebiederm.orgAcked-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>