When a bio's queue supports PCI P2PDMA, set FOLL_PCI_P2PDMA for
iov_iter_get_pages_flags(). This allows PCI P2PDMA pages to be
passed from userspace and enables the NVMe passthru requests to
use P2PDMA pages.
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20221021174116.7200-8-logang@deltatee.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When a bio's queue supports PCI P2PDMA, set FOLL_PCI_P2PDMA for
iov_iter_get_pages_flags(). This allows PCI P2PDMA pages to be passed
from userspace and enables the O_DIRECT path in iomap based filesystems
and direct to block devices.
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20221021174116.7200-7-logang@deltatee.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Consecutive zone device pages should not be merged into the same sgl
or bvec segment with other types of pages or if they belong to different
pgmaps. Otherwise getting the pgmap of a given segment is not possible
without scanning the entire segment. This helper returns true either if
both pages are not zone device pages or both pages are zone device
pages with the same pgmap.
Factor out the check for page mergability into a pages_are_mergable()
helper and add a check with zone_device_pages_are_mergeable().
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20221021174116.7200-6-logang@deltatee.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Consecutive zone device pages should not be merged into the same sgl
or bvec segment with other types of pages or if they belong to different
pgmaps. Otherwise getting the pgmap of a given segment is not possible
without scanning the entire segment. This helper returns true either if
both pages are not zone device pages or both pages are zone device
pages with the same pgmap.
Add a helper to determine if zone device pages are mergeable and use
this helper in page_is_mergeable().
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20221021174116.7200-5-logang@deltatee.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add iov_iter_get_pages_flags() and iov_iter_get_pages_alloc_flags()
which take a flags argument that is passed to get_user_pages_fast().
This is so that FOLL_PCI_P2PDMA can be passed when appropriate.
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221021174116.7200-4-logang@deltatee.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
GUP Callers that expect PCI P2PDMA pages can now set FOLL_PCI_P2PDMA to
allow obtaining P2PDMA pages. If GUP is called without the flag and a
P2PDMA page is found, it will return an error in try_grab_page() or
try_grab_folio().
The check is safe to do before taking the reference to the page in both
cases seeing the page should be protected by either the appropriate
ptl or mmap_lock; or the gup fast guarantees preventing TLB flushes.
try_grab_folio() has one call site that WARNs on failure and cannot
actually deal with the failure of this function (it seems it will
get into an infinite loop). Expand the comment there to document a
couple more conditions on why it will not fail.
FOLL_PCI_P2PDMA cannot be set if FOLL_LONGTERM is set. This is to copy
fsdax until pgmap refcounts are fixed (see the link below for more
information).
Link: https://lkml.kernel.org/r/Yy4Ot5MoOhsgYLTQ@ziepe.ca
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20221021174116.7200-3-logang@deltatee.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In order to add checks for P2PDMA memory into try_grab_page(), expand
the error return from a bool to an int/error code. Update all the
callsites handle change in usage.
Also remove the WARN_ON_ONCE() call at the callsites seeing there
already is a WARN_ON_ONCE() inside the function if it fails.
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221021174116.7200-2-logang@deltatee.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Provide NVMEM content to the NVRAM driver from a simple
memory resource. This is necessary to use NVRAM in a memory-
mapped flash device. Patch taken from OpenWrts development
tree.
This patch makes it possible to use memory-mapped NVRAM
on the D-Link DWL-8610AP and the D-Link DIR-890L.
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Cc: linux-mips@vger.kernel.org
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
[Added an export for modules potentially using the init symbol]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20221103082529.359084-1-linus.walleij@linaro.org
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
The return value from genl_op_iter_init() only tells us if
there are any policies but to begin the iteration (and therefore
load the first entry) we need to call genl_op_iter_next().
Note that it's safe to call genl_op_iter_next() on a family
with no ops, it will just return false.
This may lead to various crashes, a warning in
netlink_policy_dump_get_policy_idx() when policy is not found
or.. no problem at all if the kmalloc'ed memory happens to be
zeroed.
Fixes: b502b3185c ("genetlink: use iterator in the op to policy map dumping")
Link: https://lore.kernel.org/r/20221108204128.330287-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The kernel driver assumes hybrid CPUs will have Intel PT capabilities
that are compatible with the boot CPU. Add a test to check that is the
case.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20221104121805.5264-4-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
In preparation for adding more Intel PT testing, redefine the test_suite
to allow for adding more subtests.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20221104121805.5264-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
In preparation for adding more Intel PT testing, rename
intel-pt-pkt-decoder-test.c to intel-pt-test.c.
Subtests will later be added to intel-pt-test.c.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20221104121805.5264-2-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This adds a device tree for the BCM53016-based D-Link DWL-8610AP
access point wireless router.
The TRX-format partitions had to be named "firmware" due to
an OpenWrt patch that only accepts parting such nodes if they
are named "firmware".
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20221019193449.3036010-2-linus.walleij@linaro.org
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
pte_to_phys() assembly definition does multiple bits field transformations
to derive physical address, embedded inside a page table entry. Unlike its
C counter part i.e __pte_to_phys(), pte_to_phys() is not very apparent. It
simplifies these operations via a new macro PTE_ADDR_HIGH_SHIFT indicating
how far the pte encoded higher address bits need to be left shifted. While
here, this also updates __pte_to_phys() and __phys_to_pte_val().
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20221107141753.2938621-1-anshuman.khandual@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
arm_smccc_1_1_invoke() which is called later on in the function
will return failure if there's no conduit (or pre-SMCCC 1.1),
hence the check is unnecessary.
Suggested-by: Steven Price <steven.price@arm.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20221104061659.4116508-1-usama.arif@bytedance.com
Signed-off-by: Will Deacon <will@kernel.org>
Implement dynamic shadow call stack support on Clang, by parsing the
unwind tables at init time to locate all occurrences of PACIASP/AUTIASP
instructions, and replacing them with the shadow call stack push and pop
instructions, respectively.
This is useful because the overhead of the shadow call stack is
difficult to justify on hardware that implements pointer authentication
(PAC), and given that the PAC instructions are executed as NOPs on
hardware that doesn't, we can just replace them without breaking
anything. As PACIASP/AUTIASP are guaranteed to be paired with respect to
manipulations of the return address, replacing them 1:1 with shadow call
stack pushes and pops is guaranteed to result in the desired behavior.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20221027155908.1940624-4-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
In order to allow arches to use code patching to conditionally emit the
shadow stack pushes and pops, rather than always taking the performance
hit even on CPUs that implement alternatives such as stack pointer
authentication on arm64, add a Kconfig symbol that can be set by the
arch to omit the SCS codegen itself, without otherwise affecting how
support code for SCS and compiler options (for register reservation, for
instance) are emitted.
Also, add a static key and some plumbing to omit the allocation of
shadow call stack for dynamic SCS configurations if SCS is disabled at
runtime.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20221027155908.1940624-3-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Enable asynchronous unwind table generation for both the core kernel as
well as modules, and emit the resulting .eh_frame sections as init code
so we can use the unwind directives for code patching at boot or module
load time.
This will be used by dynamic shadow call stack support, which will rely
on code patching rather than compiler codegen to emit the shadow call
stack push and pop instructions.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20221027155908.1940624-2-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
PMR735a also appears to be bundled with some SMD RPM SoCs.
Document it.
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221109110846.45789-1-konrad.dybcio@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>
PMR735a is already supported in the RPMH regulator driver, but
there are cases where it's bundled with SMD RPM SoCs. Port it over
to qcom_smd-regulator to enable usage in such cases.
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20221109110846.45789-2-konrad.dybcio@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>
The function check_length() is supposed to check the length of inbound
packets on responder, but it actually has been a stub since the driver was
born. Let it check the payload length and the DMA length.
Signed-off-by: Daisuke Matsuda <matsuda-daisuke@fujitsu.com>
Link: https://lore.kernel.org/r/20221107055338.357184-1-matsuda-daisuke@fujitsu.com
Reviewed-by: Li Zhijian <lizhijian@fujitsu.com>
Acked-by: Zhu Yanjun <zyjzyj2000@gmail.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
FEAT_SVE2p1 introduces a number of new SVE instructions. Since there is no
new architectural state added kernel support is simply a new hwcap which
lets userspace know that the feature is supported.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20221017152520.1039165-6-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Since the newly added instruction is in the HINT space we can't reasonably
test for it actually being present.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20221017152520.1039165-5-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
FEAT_RPRFM adds a new range prefetch hint within the existing PRFM space
for range prefetch hinting. Add a new hwcap to allow userspace to discover
support for the new instruction.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20221017152520.1039165-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Add FEAT_CSSC to the set of features checked by the hwcap selftest.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20221017152520.1039165-3-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
FEAT_CSSC adds a number of new instructions usable to optimise common short
sequences of instructions, add a hwcap indicating that the feature is
available and can be used by userspace.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20221017152520.1039165-2-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Before version 15.0.0 llvm's integrated assembler may silently
generate corrupted code on s390. See e.g. commit e9953b729b
("s390/boot: workaround llvm IAS bug") for further details.
While there have been workarounds applied for all known existing
locations, there is nothing that prevents that new code with
problematic patterns will be added.
Therefore raise the minimum clang version to 15.0.0. Note that llvm
commit e547b04d5b2c ("[SystemZ] Bugfix for symbolic displacements."),
which is included in 15.0.0, fixes the broken code generation.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20221031123456.3872220-1-hca@linux.ibm.com
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
virt/kvm/irqchip.c is including "irq.h" from the arch-specific KVM source
directory (i.e. not from arch/*/include) for the sole purpose of retrieving
irqchip_in_kernel.
Making the function inline in a header that is already included,
such as asm/kvm_host.h, is not possible because it needs to look at
struct kvm which is defined after asm/kvm_host.h is included. So add a
kvm_arch_irqchip_in_kernel non-inline function; irqchip_in_kernel() is
only performance critical on arm64 and x86, and the non-inline function
is enough on all other architectures.
irq.h can then be deleted from all architectures except x86.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Defer reprogramming counters and handling overflow via KVM_REQ_PMU
when incrementing counters. KVM skips emulated WRMSR in the VM-Exit
fastpath, the fastpath runs with IRQs disabled, skipping instructions
can increment and reprogram counters, reprogramming counters can
sleep, and sleeping is disallowed while IRQs are disabled.
[*] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580
[*] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 2981888, name: CPU 15/KVM
[*] preempt_count: 1, expected: 0
[*] RCU nest depth: 0, expected: 0
[*] INFO: lockdep is turned off.
[*] irq event stamp: 0
[*] hardirqs last enabled at (0): [<0000000000000000>] 0x0
[*] hardirqs last disabled at (0): [<ffffffff8121222a>] copy_process+0x146a/0x62d0
[*] softirqs last enabled at (0): [<ffffffff81212269>] copy_process+0x14a9/0x62d0
[*] softirqs last disabled at (0): [<0000000000000000>] 0x0
[*] Preemption disabled at:
[*] [<ffffffffc2063fc1>] vcpu_enter_guest+0x1001/0x3dc0 [kvm]
[*] CPU: 17 PID: 2981888 Comm: CPU 15/KVM Kdump: 5.19.0-rc1-g239111db364c-dirty #2
[*] Call Trace:
[*] <TASK>
[*] dump_stack_lvl+0x6c/0x9b
[*] __might_resched.cold+0x22e/0x297
[*] __mutex_lock+0xc0/0x23b0
[*] perf_event_ctx_lock_nested+0x18f/0x340
[*] perf_event_pause+0x1a/0x110
[*] reprogram_counter+0x2af/0x1490 [kvm]
[*] kvm_pmu_trigger_event+0x429/0x950 [kvm]
[*] kvm_skip_emulated_instruction+0x48/0x90 [kvm]
[*] handle_fastpath_set_msr_irqoff+0x349/0x3b0 [kvm]
[*] vmx_vcpu_run+0x268e/0x3b80 [kvm_intel]
[*] vcpu_enter_guest+0x1d22/0x3dc0 [kvm]
Add a field to kvm_pmc to track the previous counter value in order
to defer overflow detection to kvm_pmu_handle_event() (the counter must
be paused before handling overflow, and that may increment the counter).
Opportunistically shrink sizeof(struct kvm_pmc) a bit.
Suggested-by: Wanpeng Li <wanpengli@tencent.com>
Fixes: 9cd803d496 ("KVM: x86: Update vPMCs when retiring instructions")
Signed-off-by: Like Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20220831085328.45489-6-likexu@tencent.com
[sean: avoid re-triggering KVM_REQ_PMU on overflow, tweak changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220923001355.3741194-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Batch reprogramming PMU counters by setting KVM_REQ_PMU and thus
deferring reprogramming kvm_pmu_handle_event() to avoid reprogramming
a counter multiple times during a single VM-Exit.
Deferring programming will also allow KVM to fix a bug where immediately
reprogramming a counter can result in sleeping (taking a mutex) while
interrupts are disabled in the VM-Exit fastpath.
Introduce kvm_pmu_request_counter_reprogam() to make it obvious that
KVM is _requesting_ a reprogram and not actually doing the reprogram.
Opportunistically refine related comments to avoid misunderstandings.
Signed-off-by: Like Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20220831085328.45489-5-likexu@tencent.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220923001355.3741194-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When reprogramming a counter, clear the counter's "reprogram pending" bit
if the counter is disabled (by the guest) or is disallowed (by the
userspace filter). In both cases, there's no need to re-attempt
programming on the next coincident KVM_REQ_PMU as enabling the counter by
either method will trigger reprogramming.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220923001355.3741194-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Force vCPUs to reprogram all counters on a PMU filter change to provide
a sane ABI for userspace. Use the existing KVM_REQ_PMU to do the
programming, and take advantage of the fact that the reprogram_pmi bitmap
fits in a u64 to set all bits in a single atomic update. Note, setting
the bitmap and making the request needs to be done _after_ the SRCU
synchronization to ensure that vCPUs will reprogram using the new filter.
KVM's current "lazy" approach is confusing and non-deterministic. It's
confusing because, from a developer perspective, the code is buggy as it
makes zero sense to let userspace modify the filter but then not actually
enforce the new filter. The lazy approach is non-deterministic because
KVM enforces the filter whenever a counter is reprogrammed, not just on
guest WRMSRs, i.e. a guest might gain/lose access to an event at random
times depending on what is going on in the host.
Note, the resulting behavior is still non-determinstic while the filter
is in flux. If userspace wants to guarantee deterministic behavior, all
vCPUs should be paused during the filter update.
Jim Mattson <jmattson@google.com>
Fixes: 66bb8a065f ("KVM: x86: PMU Event Filter")
Cc: Aaron Lewis <aaronlewis@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220923001355.3741194-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Extend the accounting sanity check in kvm_recover_nx_huge_pages() to the
TDP MMU, i.e. verify that zapping a shadow page unaccounts the disallowed
NX huge page regardless of the MMU type. Recovery runs while holding
mmu_lock for write and so it should be impossible to get false positives
on the WARN.
Suggested-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221019165618.927057-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Explicitly check if a NX huge page is disallowed when determining if a
page fault needs to be forced to use a smaller sized page. KVM currently
assumes that the NX huge page mitigation is the only scenario where KVM
will force a shadow page instead of a huge page, and so unnecessarily
keeps an existing shadow page instead of replacing it with a huge page.
Any scenario that causes KVM to zap leaf SPTEs may result in having a SP
that can be made huge without violating the NX huge page mitigation.
E.g. prior to commit 5ba7c4c6d1 ("KVM: x86/MMU: Zap non-leaf SPTEs when
disabling dirty logging"), KVM would keep shadow pages after disabling
dirty logging due to a live migration being canceled, resulting in
degraded performance due to running with 4kb pages instead of huge pages.
Although the dirty logging case is "fixed", that fix is coincidental,
i.e. is an implementation detail, and there are other scenarios where KVM
will zap leaf SPTEs. E.g. zapping leaf SPTEs in response to a host page
migration (mmu_notifier invalidation) to create a huge page would yield a
similar result; KVM would see the shadow-present non-leaf SPTE and assume
a huge page is disallowed.
Fixes: b8e8c8303f ("kvm: mmu: ITLB_MULTIHIT mitigation")
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>
[sean: use spte_to_child_sp(), massage changelog, fold into if-statement]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Message-Id: <20221019165618.927057-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a helper to convert a SPTE to its shadow page to deduplicate a
variety of flows and hopefully avoid future bugs, e.g. if KVM attempts to
get the shadow page for a SPTE without dropping high bits.
Opportunistically add a comment in mmu_free_root_page() documenting why
it treats the root HPA as a SPTE.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221019165618.927057-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Track the number of TDP MMU "shadow" pages instead of tracking the pages
themselves. With the NX huge page list manipulation moved out of the common
linking flow, elminating the list-based tracking means the happy path of
adding a shadow page doesn't need to acquire a spinlock and can instead
inc/dec an atomic.
Keep the tracking as the WARN during TDP MMU teardown on leaked shadow
pages is very, very useful for detecting KVM bugs.
Tracking the number of pages will also make it trivial to expose the
counter to userspace as a stat in the future, which may or may not be
desirable.
Note, the TDP MMU needs to use a separate counter (and stat if that ever
comes to be) from the existing n_used_mmu_pages. The TDP MMU doesn't bother
supporting the shrinker nor does it honor KVM_SET_NR_MMU_PAGES (because the
TDP MMU consumes so few pages relative to shadow paging), and including TDP
MMU pages in that counter would break both the shrinker and shadow MMUs,
e.g. if a VM is using nested TDP.
Cc: Yan Zhao <yan.y.zhao@intel.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Message-Id: <20221019165618.927057-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Set nx_huge_page_disallowed in TDP MMU shadow pages before making the SP
visible to other readers, i.e. before setting its SPTE. This will allow
KVM to query the flag when determining if a shadow page can be replaced
by a NX huge page without violating the rules of the mitigation.
Note, the shadow/legacy MMU holds mmu_lock for write, so it's impossible
for another CPU to see a shadow page without an up-to-date
nx_huge_page_disallowed, i.e. only the TDP MMU needs the complicated
dance.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Message-Id: <20221019165618.927057-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Account and track NX huge pages for nonpaging MMUs so that a future
enhancement to precisely check if a shadow page can't be replaced by a NX
huge page doesn't get false positives. Without correct tracking, KVM can
get stuck in a loop if an instruction is fetching and writing data on the
same huge page, e.g. KVM installs a small executable page on the fetch
fault, replaces it with an NX huge page on the write fault, and faults
again on the fetch.
Alternatively, and perhaps ideally, KVM would simply not enforce the
workaround for nonpaging MMUs. The guest has no page tables to abuse
and KVM is guaranteed to switch to a different MMU on CR0.PG being
toggled so there's no security or performance concerns. However, getting
make_spte() to play nice now and in the future is unnecessarily complex.
In the current code base, make_spte() can enforce the mitigation if TDP
is enabled or the MMU is indirect, but make_spte() may not always have a
vCPU/MMU to work with, e.g. if KVM were to support in-line huge page
promotion when disabling dirty logging.
Without a vCPU/MMU, KVM could either pass in the correct information
and/or derive it from the shadow page, but the former is ugly and the
latter subtly non-trivial due to the possibility of direct shadow pages
in indirect MMUs. Given that using shadow paging with an unpaged guest
is far from top priority _and_ has been subjected to the workaround since
its inception, keep it simple and just fix the accounting glitch.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Message-Id: <20221019165618.927057-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Rename most of the variables/functions involved in the NX huge page
mitigation to provide consistency, e.g. lpage vs huge page, and NX huge
vs huge NX, and also to provide clarity, e.g. to make it obvious the flag
applies only to the NX huge page mitigation, not to any condition that
prevents creating a huge page.
Add a comment explaining what the newly named "possible_nx_huge_pages"
tracks.
Leave the nx_lpage_splits stat alone as the name is ABI and thus set in
stone.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Message-Id: <20221019165618.927057-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Tag shadow pages that cannot be replaced with an NX huge page regardless
of whether or not zapping the page would allow KVM to immediately create
a huge page, e.g. because something else prevents creating a huge page.
I.e. track pages that are disallowed from being NX huge pages regardless
of whether or not the page could have been huge at the time of fault.
KVM currently tracks pages that were disallowed from being huge due to
the NX workaround if and only if the page could otherwise be huge. But
that fails to handled the scenario where whatever restriction prevented
KVM from installing a huge page goes away, e.g. if dirty logging is
disabled, the host mapping level changes, etc...
Failure to tag shadow pages appropriately could theoretically lead to
false negatives, e.g. if a fetch fault requests a small page and thus
isn't tracked, and a read/write fault later requests a huge page, KVM
will not reject the huge page as it should.
To avoid yet another flag, initialize the list_head and use list_empty()
to determine whether or not a page is on the list of NX huge pages that
should be recovered.
Note, the TDP MMU accounting is still flawed as fixing the TDP MMU is
more involved due to mmu_lock being held for read. This will be
addressed in a future commit.
Fixes: 5bcaf3e171 ("KVM: x86/mmu: Account NX huge page disallowed iff huge page was requested")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221019165618.927057-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When using the flags in KVM_X86_SET_MSR_FILTER and
KVM_CAP_X86_USER_SPACE_MSR it is expected that an attempt to write to
any of the unused bits will fail. Add testing to walk over every bit
in each of the flag fields in MSR filtering and MSR exiting to verify
that unused bits return and error and used bits, i.e. valid bits,
succeed.
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Message-Id: <20220921151525.904162-6-aaronlewis@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add the mask KVM_MSR_FILTER_RANGE_VALID_MASK for the flags in the
struct kvm_msr_filter_range. This simplifies checks that validate
these flags, and makes it easier to introduce new flags in the future.
No functional change intended.
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Message-Id: <20220921151525.904162-5-aaronlewis@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add the mask KVM_MSR_FILTER_VALID_MASK for the flag in the struct
kvm_msr_filter. This makes it easier to introduce new flags in the
future.
No functional change intended.
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Message-Id: <20220921151525.904162-4-aaronlewis@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add the mask KVM_MSR_EXIT_REASON_VALID_MASK for the MSR exit reason
flags. This simplifies checks that validate these flags, and makes it
easier to introduce new flags in the future.
No functional change intended.
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Message-Id: <20220921151525.904162-3-aaronlewis@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Protect the kernel from using the flag KVM_MSR_FILTER_DEFAULT_ALLOW.
Its value is 0, and using it incorrectly could have unintended
consequences. E.g. prevent someone in the kernel from writing something
like this.
if (filter.flags & KVM_MSR_FILTER_DEFAULT_ALLOW)
<allow the MSR>
and getting confused when it doesn't work.
It would be more ideal to remove this flag altogether, but userspace
may already be using it, so protecting the kernel is all that can
reasonably be done at this point.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220921151525.904162-2-aaronlewis@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
