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Sebastian reports that commit 1c913a1c35aa ("KVM: arm64: Iterate
arm_pmus list to probe for default PMU") introduced the following splat
with CONFIG_DEBUG_PREEMPT enabled:
[70506.110187] BUG: using smp_processor_id() in preemptible [00000000] code: qemu-system-aar/3078242
[70506.119077] caller is debug_smp_processor_id+0x20/0x30
[70506.124229] CPU: 129 PID: 3078242 Comm: qemu-system-aar Tainted: G W 6.4.0-rc5 #25
[70506.133176] Hardware name: GIGABYTE R181-T92-00/MT91-FS4-00, BIOS F34 08/13/2020
[70506.140559] Call trace:
[70506.142993] dump_backtrace+0xa4/0x130
[70506.146737] show_stack+0x20/0x38
[70506.150040] dump_stack_lvl+0x48/0x60
[70506.153704] dump_stack+0x18/0x28
[70506.157007] check_preemption_disabled+0xe4/0x108
[70506.161701] debug_smp_processor_id+0x20/0x30
[70506.166046] kvm_arm_pmu_v3_set_attr+0x460/0x628
[70506.170662] kvm_arm_vcpu_arch_set_attr+0x88/0xd8
[70506.175363] kvm_arch_vcpu_ioctl+0x258/0x4a8
[70506.179632] kvm_vcpu_ioctl+0x32c/0x6b8
[70506.183465] __arm64_sys_ioctl+0xb4/0x100
[70506.187467] invoke_syscall+0x78/0x108
[70506.191205] el0_svc_common.constprop.0+0x4c/0x100
[70506.195984] do_el0_svc+0x34/0x50
[70506.199287] el0_svc+0x34/0x108
[70506.202416] el0t_64_sync_handler+0xf4/0x120
[70506.206674] el0t_64_sync+0x194/0x198
Fix the issue by using the raw variant that bypasses the debug
assertion. While at it, stick all of the nuance and UAPI baggage into a
comment for posterity.
Fixes: 1c913a1c35aa ("KVM: arm64: Iterate arm_pmus list to probe for default PMU")
Reported-by: Sebastian Ott <sebott@redhat.com>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230606184814.456743-1-oliver.upton@linux.dev
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KVM maintains a mask of supported CPUs when a vPMU type is explicitly
selected by userspace and is used to reject any attempt to run the vCPU
on an unsupported CPU. This is great, but we're still beholden to the
default behavior where vCPUs can be scheduled anywhere and guest
counters may silently stop working.
Avoid confusing the next poor sod to look at this code and document the
intended behavior.
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230525212723.3361524-3-oliver.upton@linux.dev
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To date KVM has relied on using a perf event to probe the core PMU at
the time of vPMU initialization. Behind the scenes perf_event_init()
would iteratively walk the PMUs of the system and return the PMU that
could handle the event. However, an upcoming change in perf core will
drop the iterative walk, thereby breaking the fragile dance we do on the
KVM side.
Avoid the problem altogether by iterating over the list of supported
PMUs maintained in KVM, returning the core PMU that matches the CPU
we were called on.
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230525212723.3361524-2-oliver.upton@linux.dev
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Pull kvm updates from Paolo Bonzini:
"s390:
- More phys_to_virt conversions
- Improvement of AP management for VSIE (nested virtualization)
ARM64:
- Numerous fixes for the pathological lock inversion issue that
plagued KVM/arm64 since... forever.
- New framework allowing SMCCC-compliant hypercalls to be forwarded
to userspace, hopefully paving the way for some more features being
moved to VMMs rather than be implemented in the kernel.
- Large rework of the timer code to allow a VM-wide offset to be
applied to both virtual and physical counters as well as a
per-timer, per-vcpu offset that complements the global one. This
last part allows the NV timer code to be implemented on top.
- A small set of fixes to make sure that we don't change anything
affecting the EL1&0 translation regime just after having having
taken an exception to EL2 until we have executed a DSB. This
ensures that speculative walks started in EL1&0 have completed.
- The usual selftest fixes and improvements.
x86:
- Optimize CR0.WP toggling by avoiding an MMU reload when TDP is
enabled, and by giving the guest control of CR0.WP when EPT is
enabled on VMX (VMX-only because SVM doesn't support per-bit
controls)
- Add CR0/CR4 helpers to query single bits, and clean up related code
where KVM was interpreting kvm_read_cr4_bits()'s "unsigned long"
return as a bool
- Move AMD_PSFD to cpufeatures.h and purge KVM's definition
- Avoid unnecessary writes+flushes when the guest is only adding new
PTEs
- Overhaul .sync_page() and .invlpg() to utilize .sync_page()'s
optimizations when emulating invalidations
- Clean up the range-based flushing APIs
- Revamp the TDP MMU's reaping of Accessed/Dirty bits to clear a
single A/D bit using a LOCK AND instead of XCHG, and skip all of
the "handle changed SPTE" overhead associated with writing the
entire entry
- Track the number of "tail" entries in a pte_list_desc to avoid
having to walk (potentially) all descriptors during insertion and
deletion, which gets quite expensive if the guest is spamming
fork()
- Disallow virtualizing legacy LBRs if architectural LBRs are
available, the two are mutually exclusive in hardware
- Disallow writes to immutable feature MSRs (notably
PERF_CAPABILITIES) after KVM_RUN, similar to CPUID features
- Overhaul the vmx_pmu_caps selftest to better validate
PERF_CAPABILITIES
- Apply PMU filters to emulated events and add test coverage to the
pmu_event_filter selftest
- AMD SVM:
- Add support for virtual NMIs
- Fixes for edge cases related to virtual interrupts
- Intel AMX:
- Don't advertise XTILE_CFG in KVM_GET_SUPPORTED_CPUID if
XTILE_DATA is not being reported due to userspace not opting in
via prctl()
- Fix a bug in emulation of ENCLS in compatibility mode
- Allow emulation of NOP and PAUSE for L2
- AMX selftests improvements
- Misc cleanups
MIPS:
- Constify MIPS's internal callbacks (a leftover from the hardware
enabling rework that landed in 6.3)
Generic:
- Drop unnecessary casts from "void *" throughout kvm_main.c
- Tweak the layout of "struct kvm_mmu_memory_cache" to shrink the
struct size by 8 bytes on 64-bit kernels by utilizing a padding
hole
Documentation:
- Fix goof introduced by the conversion to rST"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (211 commits)
KVM: s390: pci: fix virtual-physical confusion on module unload/load
KVM: s390: vsie: clarifications on setting the APCB
KVM: s390: interrupt: fix virtual-physical confusion for next alert GISA
KVM: arm64: Have kvm_psci_vcpu_on() use WRITE_ONCE() to update mp_state
KVM: arm64: Acquire mp_state_lock in kvm_arch_vcpu_ioctl_vcpu_init()
KVM: selftests: Test the PMU event "Instructions retired"
KVM: selftests: Copy full counter values from guest in PMU event filter test
KVM: selftests: Use error codes to signal errors in PMU event filter test
KVM: selftests: Print detailed info in PMU event filter asserts
KVM: selftests: Add helpers for PMC asserts in PMU event filter test
KVM: selftests: Add a common helper for the PMU event filter guest code
KVM: selftests: Fix spelling mistake "perrmited" -> "permitted"
KVM: arm64: vhe: Drop extra isb() on guest exit
KVM: arm64: vhe: Synchronise with page table walker on MMU update
KVM: arm64: pkvm: Document the side effects of kvm_flush_dcache_to_poc()
KVM: arm64: nvhe: Synchronise with page table walker on TLBI
KVM: arm64: Handle 32bit CNTPCTSS traps
KVM: arm64: nvhe: Synchronise with page table walker on vcpu run
KVM: arm64: vgic: Don't acquire its_lock before config_lock
KVM: selftests: Add test to verify KVM's supported XCR0
...
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* kvm-arm64/smccc-filtering:
: .
: SMCCC call filtering and forwarding to userspace, courtesy of
: Oliver Upton. From the cover letter:
:
: "The Arm SMCCC is rather prescriptive in regards to the allocation of
: SMCCC function ID ranges. Many of the hypercall ranges have an
: associated specification from Arm (FF-A, PSCI, SDEI, etc.) with some
: room for vendor-specific implementations.
:
: The ever-expanding SMCCC surface leaves a lot of work within KVM for
: providing new features. Furthermore, KVM implements its own
: vendor-specific ABI, with little room for other implementations (like
: Hyper-V, for example). Rather than cramming it all into the kernel we
: should provide a way for userspace to handle hypercalls."
: .
KVM: selftests: Fix spelling mistake "KVM_HYPERCAL_EXIT_SMC" -> "KVM_HYPERCALL_EXIT_SMC"
KVM: arm64: Test that SMC64 arch calls are reserved
KVM: arm64: Prevent userspace from handling SMC64 arch range
KVM: arm64: Expose SMC/HVC width to userspace
KVM: selftests: Add test for SMCCC filter
KVM: selftests: Add a helper for SMCCC calls with SMC instruction
KVM: arm64: Let errors from SMCCC emulation to reach userspace
KVM: arm64: Return NOT_SUPPORTED to guest for unknown PSCI version
KVM: arm64: Introduce support for userspace SMCCC filtering
KVM: arm64: Add support for KVM_EXIT_HYPERCALL
KVM: arm64: Use a maple tree to represent the SMCCC filter
KVM: arm64: Refactor hvc filtering to support different actions
KVM: arm64: Start handling SMCs from EL1
KVM: arm64: Rename SMC/HVC call handler to reflect reality
KVM: arm64: Add vm fd device attribute accessors
KVM: arm64: Add a helper to check if a VM has ran once
KVM: x86: Redefine 'longmode' as a flag for KVM_EXIT_HYPERCALL
Signed-off-by: Marc Zyngier <maz@kernel.org>
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The test_bit(...) pattern is quite a lot of keystrokes. Replace
existing callsites with a helper.
No functional change intended.
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230404154050.2270077-3-oliver.upton@linux.dev
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Currently, with VHE, KVM enables the EL0 event counting for the
guest on vcpu_load() or KVM enables it as a part of the PMU
register emulation process, when needed. However, in the migration
case (with VHE), the same handling is lacking, as vPMU register
values that were restored by userspace haven't been propagated yet
(the PMU events haven't been created) at the vcpu load-time on the
first KVM_RUN (kvm_vcpu_pmu_restore_guest() called from vcpu_load()
on the first KVM_RUN won't do anything as events_{guest,host} of
kvm_pmu_events are still zero).
So, with VHE, enable the guest's EL0 event counting on the first
KVM_RUN (after the migration) when needed. More specifically,
have kvm_pmu_handle_pmcr() call kvm_vcpu_pmu_restore_guest()
so that kvm_pmu_handle_pmcr() on the first KVM_RUN can take
care of it.
Fixes: d0c94c49792c ("KVM: arm64: Restore PMU configuration on first run")
Cc: stable@vger.kernel.org
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Reiji Watanabe <reijiw@google.com>
Link: https://lore.kernel.org/r/20230329023944.2488484-1-reijiw@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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There are various bits of VM-scoped data that can only be configured
before the first call to KVM_RUN, such as the hypercall bitmaps and
the PMU. As these fields are protected by the kvm->lock and accessed
while holding vcpu->mutex, this is yet another example of lock
inversion.
Change out the kvm->lock for kvm->arch.config_lock in all of these
instances. Opportunistically simplify the locking mechanics of the
PMU configuration by holding the config_lock for the entirety of
kvm_arm_pmu_v3_set_attr().
Note that this also addresses a couple of bugs. There is an unguarded
read of the PMU version in KVM_ARM_VCPU_PMU_V3_FILTER which could race
with KVM_ARM_VCPU_PMU_V3_SET_PMU. Additionally, until now writes to the
per-vCPU vPMU irq were not serialized VM-wide, meaning concurrent calls
to KVM_ARM_VCPU_PMU_V3_IRQ could lead to a false positive in
pmu_irq_is_valid().
Cc: stable@vger.kernel.org
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230327164747.2466958-4-oliver.upton@linux.dev
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Presently, when a guest writes 1 to PMCR_EL0.{C,P}, which is WO/RAZ,
KVM saves the register value, including these bits.
When userspace reads the register using KVM_GET_ONE_REG, KVM returns
the saved register value as it is (the saved value might have these
bits set). This could result in userspace setting these bits on the
destination during migration. Consequently, KVM may end up resetting
the vPMU counter registers (PMCCNTR_EL0 and/or PMEVCNTR<n>_EL0) to
zero on the first KVM_RUN after migration.
Fix this by not saving those bits when a guest writes 1 to those bits.
Fixes: ab9468340d2b ("arm64: KVM: Add access handler for PMCR register")
Cc: stable@vger.kernel.org
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Reiji Watanabe <reijiw@google.com>
Link: https://lore.kernel.org/r/20230313033234.1475987-1-reijiw@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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Fix the bogus masking when computing the period of a 64bit counter
with 32bit overflow. It really should be treated like a 32bit counter
for the purpose of the period.
Reported-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/Y4jbosgHbUDI0WF4@google.com
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Userspace can play some dirty tricks on us by selecting a given
PMU version (such as PMUv3p5), restore a PMCR_EL0 value that
has PMCR_EL0.LP set, and then switch the PMU version to PMUv3p1,
for example. In this situation, we end-up with PMCR_EL0.LP being
set and spreading havoc in the PMU emulation.
This is specially hard as the first two step can be done on
one vcpu and the third step on another, meaning that we need
to sanitise *all* vcpus when the PMU version is changed.
In orer to avoid a pretty complicated locking situation,
defer the sanitisation of PMCR_EL0 to the point where the
vcpu is actually run for the first tine, using the existing
KVM_REQ_RELOAD_PMU request that calls into kvm_pmu_handle_pmcr().
There is still an obscure corner case where userspace could
do the above trick, and then save the VM without running it.
They would then observe an inconsistent state (PMUv3.1 + LP set),
but that state will be fixed on the first run anyway whenever
the guest gets restored on a host.
Reported-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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kvm_host_pmu_init() returns when detected PMU is either not implemented, or
implementation defined. kvm_pmu_probe_armpmu() also has a similar situation.
Extracted ID_AA64DFR0_EL1_PMUVer value, when PMU is not implemented is '0',
which can be replaced with ID_AA64DFR0_EL1_PMUVer_NI defined as '0b0000'.
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-perf-users@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221128135629.118346-1-anshuman.khandual@arm.com
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The PMU code has historically been torn between referencing a counter
as a pair vcpu+index or as the PMC pointer.
Given that it is pretty easy to go from one representation to
the other, standardise on the latter which, IMHO, makes the
code slightly more readable. YMMV.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221113163832.3154370-17-maz@kernel.org
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The way we compute the target vcpu on getting an overflow is
a bit odd, as we use the PMC array as an anchor for kvm_pmc_to_vcpu,
while we could directly compute the correct address.
Get rid of the intermediate step and directly compute the target
vcpu.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221113163832.3154370-16-maz@kernel.org
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Now that the infrastructure is in place, bump the PMU support up
to PMUv3p5.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221113163832.3154370-15-maz@kernel.org
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PMUv3p5 (which is mandatory with ARMv8.5) comes with some extra
features:
- All counters are 64bit
- The overflow point is controlled by the PMCR_EL0.LP bit
Add the required checks in the helpers that control counter
width and overflow, as well as the sysreg handling for the LP
bit. A new kvm_pmu_is_3p5() helper makes it easy to spot the
PMUv3p5 specific handling.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221113163832.3154370-14-maz@kernel.org
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As further patches will enable the selection of a PMU revision
from userspace, sample the supported PMU revision at VM creation
time, rather than building each time the ID_AA64DFR0_EL1 register
is accessed.
This shouldn't result in any change in behaviour.
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221113163832.3154370-11-maz@kernel.org
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Even when using PMUv3p5 (which implies 64bit counters), there is
no way for AArch32 to write to the top 32 bits of the counters.
The only way to influence these bits (other than by counting
events) is by writing PMCR.P==1.
Make sure we obey the architecture and preserve the top 32 bits
on a counter update.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221113163832.3154370-10-maz@kernel.org
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kvm_pmu_set_counter_value() is pretty odd, as it tries to update
the counter value while taking into account the value that is
currently held by the running perf counter.
This is not only complicated, this is quite wrong. Nowhere in
the architecture is it said that the counter would be offset
by something that is pending. The counter should be updated
with the value set by SW, and start counting from there if
required.
Remove the odd computation and just assign the provided value
after having released the perf event (which is then restarted).
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221113163832.3154370-9-maz@kernel.org
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In order to reduce the boilerplate code, add two helpers returning
the counter register index (resp. the event register) in the vcpu
register file from the counter index.
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221113163832.3154370-8-maz@kernel.org
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The current PMU emulation sometimes narrows counters to 32bit
if the counter isn't the cycle counter. As this is going to
change with PMUv3p5 where the counters are all 64bit, fix
the couple of cases where this happens unconditionally.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Link: https://lore.kernel.org/r/20221113163832.3154370-7-maz@kernel.org
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For 64bit counters that overflow on a 32bit boundary, make
sure we only check the bottom 32bit to generate a CHAIN event.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Link: https://lore.kernel.org/r/20221113163832.3154370-6-maz@kernel.org
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The PMU architecture makes a subtle difference between a 64bit
counter and a counter that has a 64bit overflow. This is for example
the case of the cycle counter, which can generate an overflow on
a 32bit boundary if PMCR_EL0.LC==0 despite the accumulation being
done on 64 bits.
Use this distinction in the few cases where it matters in the code,
as we will reuse this with PMUv3p5 long counters.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221113163832.3154370-5-maz@kernel.org
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Even when the underlying HW doesn't offer the CHAIN event
(which happens with QEMU), we can always support it as we're
in control of the counter overflow.
Always advertise the event via PMCEID0_EL0.
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221113163832.3154370-4-maz@kernel.org
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pseudocode
Ricardo recently pointed out that the PMU chained counter emulation
in KVM wasn't quite behaving like the one on actual hardware, in
the sense that a chained counter would expose an overflow on
both halves of a chained counter, while KVM would only expose the
overflow on the top half.
The difference is subtle, but significant. What does the architecture
say (DDI0087 H.a):
- Up to PMUv3p4, all counters but the cycle counter are 32bit
- A 32bit counter that overflows generates a CHAIN event on the
adjacent counter after exposing its own overflow status
- The CHAIN event is accounted if the counter is correctly
configured (CHAIN event selected and counter enabled)
This all means that our current implementation (which uses 64bit
perf events) prevents us from emulating this overflow on the lower half.
How to fix this? By implementing the above, to the letter.
This largely results in code deletion, removing the notions of
"counter pair", "chained counters", and "canonical counter".
The code is further restructured to make the CHAIN handling similar
to SWINC, as the two are now extremely similar in behaviour.
Reported-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Link: https://lore.kernel.org/r/20221113163832.3154370-3-maz@kernel.org
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Currently the kernel refers to the versions of the PMU and SPE features by
the version of the architecture where those features were updated but the
ARM refers to them using the FEAT_ names for the features. To improve
consistency and help with updating for newer features and since v9 will
make our current naming scheme a bit more confusing update the macros
identfying features to use the FEAT_ based scheme.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220910163354.860255-4-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Normally we include the full register name in the defines for fields within
registers but this has not been followed for ID registers. In preparation
for automatic generation of defines add the _EL1s into the defines for
ID_AA64DFR0_EL1 to follow the convention. No functional changes.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220910163354.860255-3-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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The naming scheme the architecture uses for the fields in ID_AA64DFR0_EL1
does not align well with kernel conventions, using as it does a lot of
MixedCase in various arrangements. In preparation for automatically
generating the defines for this register rename the defines used to match
what is in the architecture.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220910163354.860255-2-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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* kvm-arm64/per-vcpu-host-pmu-data:
: .
: Pass the host PMU state in the vcpu to avoid the use of additional
: shared memory between EL1 and EL2 (this obviously only applies
: to nVHE and Protected setups).
:
: Patches courtesy of Fuad Tabba.
: .
KVM: arm64: pmu: Restore compilation when HW_PERF_EVENTS isn't selected
KVM: arm64: Reenable pmu in Protected Mode
KVM: arm64: Pass pmu events to hyp via vcpu
KVM: arm64: Repack struct kvm_pmu to reduce size
KVM: arm64: Wrapper for getting pmu_events
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Now that the pmu code does not access hyp data, reenable it in
protected mode.
Once fully supported, protected VMs will not have pmu support,
since that could leak information. However, non-protected VMs in
protected mode should have pmu support if available.
Signed-off-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220510095710.148178-5-tabba@google.com
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kvm->arch.arm_pmu is set when userspace attempts to set the first PMU
attribute. As certain attributes are mandatory, arm_pmu ends up always
being set to a valid arm_pmu, otherwise KVM will refuse to run the VCPU.
However, this only happens if the VCPU has the PMU feature. If the VCPU
doesn't have the feature bit set, kvm->arch.arm_pmu will be left
uninitialized and equal to NULL.
KVM doesn't do ID register emulation for 32-bit guests and accesses to the
PMU registers aren't gated by the pmu_visibility() function. This is done
to prevent injecting unexpected undefined exceptions in guests which have
detected the presence of a hardware PMU. But even though the VCPU feature
is missing, KVM still attempts to emulate certain aspects of the PMU when
PMU registers are accessed. This leads to a NULL pointer dereference like
this one, which happens on an odroid-c4 board when running the
kvm-unit-tests pmu-cycle-counter test with kvmtool and without the PMU
feature being set:
[ 454.402699] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000150
[ 454.405865] Mem abort info:
[ 454.408596] ESR = 0x96000004
[ 454.411638] EC = 0x25: DABT (current EL), IL = 32 bits
[ 454.416901] SET = 0, FnV = 0
[ 454.419909] EA = 0, S1PTW = 0
[ 454.423010] FSC = 0x04: level 0 translation fault
[ 454.427841] Data abort info:
[ 454.430687] ISV = 0, ISS = 0x00000004
[ 454.434484] CM = 0, WnR = 0
[ 454.437404] user pgtable: 4k pages, 48-bit VAs, pgdp=000000000c924000
[ 454.443800] [0000000000000150] pgd=0000000000000000, p4d=0000000000000000
[ 454.450528] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[ 454.456036] Modules linked in:
[ 454.459053] CPU: 1 PID: 267 Comm: kvm-vcpu-0 Not tainted 5.18.0-rc4 #113
[ 454.465697] Hardware name: Hardkernel ODROID-C4 (DT)
[ 454.470612] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 454.477512] pc : kvm_pmu_event_mask.isra.0+0x14/0x74
[ 454.482427] lr : kvm_pmu_set_counter_event_type+0x2c/0x80
[ 454.487775] sp : ffff80000a9839c0
[ 454.491050] x29: ffff80000a9839c0 x28: ffff000000a83a00 x27: 0000000000000000
[ 454.498127] x26: 0000000000000000 x25: 0000000000000000 x24: ffff00000a510000
[ 454.505198] x23: ffff000000a83a00 x22: ffff000003b01000 x21: 0000000000000000
[ 454.512271] x20: 000000000000001f x19: 00000000000003ff x18: 0000000000000000
[ 454.519343] x17: 000000008003fe98 x16: 0000000000000000 x15: 0000000000000000
[ 454.526416] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
[ 454.533489] x11: 000000008003fdbc x10: 0000000000009d20 x9 : 000000000000001b
[ 454.540561] x8 : 0000000000000000 x7 : 0000000000000d00 x6 : 0000000000009d00
[ 454.547633] x5 : 0000000000000037 x4 : 0000000000009d00 x3 : 0d09000000000000
[ 454.554705] x2 : 000000000000001f x1 : 0000000000000000 x0 : 0000000000000000
[ 454.561779] Call trace:
[ 454.564191] kvm_pmu_event_mask.isra.0+0x14/0x74
[ 454.568764] kvm_pmu_set_counter_event_type+0x2c/0x80
[ 454.573766] access_pmu_evtyper+0x128/0x170
[ 454.577905] perform_access+0x34/0x80
[ 454.581527] kvm_handle_cp_32+0x13c/0x160
[ 454.585495] kvm_handle_cp15_32+0x1c/0x30
[ 454.589462] handle_exit+0x70/0x180
[ 454.592912] kvm_arch_vcpu_ioctl_run+0x1c4/0x5e0
[ 454.597485] kvm_vcpu_ioctl+0x23c/0x940
[ 454.601280] __arm64_sys_ioctl+0xa8/0xf0
[ 454.605160] invoke_syscall+0x48/0x114
[ 454.608869] el0_svc_common.constprop.0+0xd4/0xfc
[ 454.613527] do_el0_svc+0x28/0x90
[ 454.616803] el0_svc+0x34/0xb0
[ 454.619822] el0t_64_sync_handler+0xa4/0x130
[ 454.624049] el0t_64_sync+0x18c/0x190
[ 454.627675] Code: a9be7bfd 910003fd f9000bf3 52807ff3 (b9415001)
[ 454.633714] ---[ end trace 0000000000000000 ]---
In this particular case, Linux hasn't detected the presence of a hardware
PMU because the PMU node is missing from the DTB, so userspace would have
been unable to set the VCPU PMU feature even if it attempted it. What
happens is that the 32-bit guest reads ID_DFR0, which advertises the
presence of the PMU, and when it tries to program a counter, it triggers
the NULL pointer dereference because kvm->arch.arm_pmu is NULL.
kvm-arch.arm_pmu was introduced by commit 46b187821472 ("KVM: arm64:
Keep a per-VM pointer to the default PMU"). Until that commit, this
error would be triggered instead:
[ 73.388140] ------------[ cut here ]------------
[ 73.388189] Unknown PMU version 0
[ 73.390420] WARNING: CPU: 1 PID: 264 at arch/arm64/kvm/pmu-emul.c:36 kvm_pmu_event_mask.isra.0+0x6c/0x74
[ 73.399821] Modules linked in:
[ 73.402835] CPU: 1 PID: 264 Comm: kvm-vcpu-0 Not tainted 5.17.0 #114
[ 73.409132] Hardware name: Hardkernel ODROID-C4 (DT)
[ 73.414048] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 73.420948] pc : kvm_pmu_event_mask.isra.0+0x6c/0x74
[ 73.425863] lr : kvm_pmu_event_mask.isra.0+0x6c/0x74
[ 73.430779] sp : ffff80000a8db9b0
[ 73.434055] x29: ffff80000a8db9b0 x28: ffff000000dbaac0 x27: 0000000000000000
[ 73.441131] x26: ffff000000dbaac0 x25: 00000000c600000d x24: 0000000000180720
[ 73.448203] x23: ffff800009ffbe10 x22: ffff00000b612000 x21: 0000000000000000
[ 73.455276] x20: 000000000000001f x19: 0000000000000000 x18: ffffffffffffffff
[ 73.462348] x17: 000000008003fe98 x16: 0000000000000000 x15: 0720072007200720
[ 73.469420] x14: 0720072007200720 x13: ffff800009d32488 x12: 00000000000004e6
[ 73.476493] x11: 00000000000001a2 x10: ffff800009d32488 x9 : ffff800009d32488
[ 73.483565] x8 : 00000000ffffefff x7 : ffff800009d8a488 x6 : ffff800009d8a488
[ 73.490638] x5 : ffff0000f461a9d8 x4 : 0000000000000000 x3 : 0000000000000001
[ 73.497710] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff000000dbaac0
[ 73.504784] Call trace:
[ 73.507195] kvm_pmu_event_mask.isra.0+0x6c/0x74
[ 73.511768] kvm_pmu_set_counter_event_type+0x2c/0x80
[ 73.516770] access_pmu_evtyper+0x128/0x16c
[ 73.520910] perform_access+0x34/0x80
[ 73.524532] kvm_handle_cp_32+0x13c/0x160
[ 73.528500] kvm_handle_cp15_32+0x1c/0x30
[ 73.532467] handle_exit+0x70/0x180
[ 73.535917] kvm_arch_vcpu_ioctl_run+0x20c/0x6e0
[ 73.540489] kvm_vcpu_ioctl+0x2b8/0x9e0
[ 73.544283] __arm64_sys_ioctl+0xa8/0xf0
[ 73.548165] invoke_syscall+0x48/0x114
[ 73.551874] el0_svc_common.constprop.0+0xd4/0xfc
[ 73.556531] do_el0_svc+0x28/0x90
[ 73.559808] el0_svc+0x28/0x80
[ 73.562826] el0t_64_sync_handler+0xa4/0x130
[ 73.567054] el0t_64_sync+0x1a0/0x1a4
[ 73.570676] ---[ end trace 0000000000000000 ]---
[ 73.575382] kvm: pmu event creation failed -2
The root cause remains the same: kvm->arch.pmuver was never set to
something sensible because the VCPU feature itself was never set.
The odroid-c4 is somewhat of a special case, because Linux doesn't probe
the PMU. But the above errors can easily be reproduced on any hardware,
with or without a PMU driver, as long as userspace doesn't set the PMU
feature.
Work around the fact that KVM advertises a PMU even when the VCPU feature
is not set by gating all PMU emulation on the feature. The guest can still
access the registers without KVM injecting an undefined exception.
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220425145530.723858-1-alexandru.elisei@arm.com
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We currently deal with a set of booleans for VM features,
while they could be better represented as set of flags
contained in an unsigned long, similarily to what we are
doing on the CPU side.
Signed-off-by: Marc Zyngier <maz@kernel.org>
[Oliver: Flag-ify the 'ran_once' boolean]
Signed-off-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220311174001.605719-2-oupton@google.com
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Userspace can assign a PMU to a VCPU with the KVM_ARM_VCPU_PMU_V3_SET_PMU
device ioctl. If the VCPU is scheduled on a physical CPU which has a
different PMU, the perf events needed to emulate a guest PMU won't be
scheduled in and the guest performance counters will stop counting. Treat
it as an userspace error and refuse to run the VCPU in this situation.
Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220127161759.53553-7-alexandru.elisei@arm.com
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When KVM creates an event and there are more than one PMUs present on the
system, perf_init_event() will go through the list of available PMUs and
will choose the first one that can create the event. The order of the PMUs
in this list depends on the probe order, which can change under various
circumstances, for example if the order of the PMU nodes change in the DTB
or if asynchronous driver probing is enabled on the kernel command line
(with the driver_async_probe=armv8-pmu option).
Another consequence of this approach is that on heteregeneous systems all
virtual machines that KVM creates will use the same PMU. This might cause
unexpected behaviour for userspace: when a VCPU is executing on the
physical CPU that uses this default PMU, PMU events in the guest work
correctly; but when the same VCPU executes on another CPU, PMU events in
the guest will suddenly stop counting.
Fortunately, perf core allows user to specify on which PMU to create an
event by using the perf_event_attr->type field, which is used by
perf_init_event() as an index in the radix tree of available PMUs.
Add the KVM_ARM_VCPU_PMU_V3_CTRL(KVM_ARM_VCPU_PMU_V3_SET_PMU) VCPU
attribute to allow userspace to specify the arm_pmu that KVM will use when
creating events for that VCPU. KVM will make no attempt to run the VCPU on
the physical CPUs that share the PMU, leaving it up to userspace to manage
the VCPU threads' affinity accordingly.
To ensure that KVM doesn't expose an asymmetric system to the guest, the
PMU set for one VCPU will be used by all other VCPUs. Once a VCPU has run,
the PMU cannot be changed in order to avoid changing the list of available
events for a VCPU, or to change the semantics of existing events.
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220127161759.53553-6-alexandru.elisei@arm.com
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The ARM PMU driver calls kvm_host_pmu_init() after probing to tell KVM that
a hardware PMU is available for guest emulation. Heterogeneous systems can
have more than one PMU present, and the callback gets called multiple
times, once for each of them. Keep track of all the PMUs available to KVM,
as they're going to be needed later.
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220127161759.53553-5-alexandru.elisei@arm.com
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As we are about to allow selection of the PMU exposed to a guest, start by
keeping track of the default one instead of only the PMU version.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20220127161759.53553-4-alexandru.elisei@arm.com
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Userspace can specify which events a guest is allowed to use with the
KVM_ARM_VCPU_PMU_V3_FILTER attribute. The list of allowed events can be
identified by a guest from reading the PMCEID{0,1}_EL0 registers.
Changing the PMU event filter after a VCPU has run can cause reads of the
registers performed before the filter is changed to return different values
than reads performed with the new event filter in place. The architecture
defines the two registers as read-only, and this behaviour contradicts
that.
Keep track when the first VCPU has run and deny changes to the PMU event
filter to prevent this from happening.
Signed-off-by: Marc Zyngier <maz@kernel.org>
[ Alexandru E: Added commit message, updated ioctl documentation ]
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220127161759.53553-2-alexandru.elisei@arm.com
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Pull kvm updates from Paolo Bonzini:
"RISCV:
- Use common KVM implementation of MMU memory caches
- SBI v0.2 support for Guest
- Initial KVM selftests support
- Fix to avoid spurious virtual interrupts after clearing hideleg CSR
- Update email address for Anup and Atish
ARM:
- Simplification of the 'vcpu first run' by integrating it into KVM's
'pid change' flow
- Refactoring of the FP and SVE state tracking, also leading to a
simpler state and less shared data between EL1 and EL2 in the nVHE
case
- Tidy up the header file usage for the nvhe hyp object
- New HYP unsharing mechanism, finally allowing pages to be unmapped
from the Stage-1 EL2 page-tables
- Various pKVM cleanups around refcounting and sharing
- A couple of vgic fixes for bugs that would trigger once the vcpu
xarray rework is merged, but not sooner
- Add minimal support for ARMv8.7's PMU extension
- Rework kvm_pgtable initialisation ahead of the NV work
- New selftest for IRQ injection
- Teach selftests about the lack of default IPA space and page sizes
- Expand sysreg selftest to deal with Pointer Authentication
- The usual bunch of cleanups and doc update
s390:
- fix sigp sense/start/stop/inconsistency
- cleanups
x86:
- Clean up some function prototypes more
- improved gfn_to_pfn_cache with proper invalidation, used by Xen
emulation
- add KVM_IRQ_ROUTING_XEN_EVTCHN and event channel delivery
- completely remove potential TOC/TOU races in nested SVM consistency
checks
- update some PMCs on emulated instructions
- Intel AMX support (joint work between Thomas and Intel)
- large MMU cleanups
- module parameter to disable PMU virtualization
- cleanup register cache
- first part of halt handling cleanups
- Hyper-V enlightened MSR bitmap support for nested hypervisors
Generic:
- clean up Makefiles
- introduce CONFIG_HAVE_KVM_DIRTY_RING
- optimize memslot lookup using a tree
- optimize vCPU array usage by converting to xarray"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (268 commits)
x86/fpu: Fix inline prefix warnings
selftest: kvm: Add amx selftest
selftest: kvm: Move struct kvm_x86_state to header
selftest: kvm: Reorder vcpu_load_state steps for AMX
kvm: x86: Disable interception for IA32_XFD on demand
x86/fpu: Provide fpu_sync_guest_vmexit_xfd_state()
kvm: selftests: Add support for KVM_CAP_XSAVE2
kvm: x86: Add support for getting/setting expanded xstate buffer
x86/fpu: Add uabi_size to guest_fpu
kvm: x86: Add CPUID support for Intel AMX
kvm: x86: Add XCR0 support for Intel AMX
kvm: x86: Disable RDMSR interception of IA32_XFD_ERR
kvm: x86: Emulate IA32_XFD_ERR for guest
kvm: x86: Intercept #NM for saving IA32_XFD_ERR
x86/fpu: Prepare xfd_err in struct fpu_guest
kvm: x86: Add emulation for IA32_XFD
x86/fpu: Provide fpu_update_guest_xfd() for IA32_XFD emulation
kvm: x86: Enable dynamic xfeatures at KVM_SET_CPUID2
x86/fpu: Provide fpu_enable_guest_xfd_features() for KVM
x86/fpu: Add guest support to xfd_enable_feature()
...
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git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm64 updates for Linux 5.16
- Simplification of the 'vcpu first run' by integrating it into
KVM's 'pid change' flow
- Refactoring of the FP and SVE state tracking, also leading to
a simpler state and less shared data between EL1 and EL2 in
the nVHE case
- Tidy up the header file usage for the nvhe hyp object
- New HYP unsharing mechanism, finally allowing pages to be
unmapped from the Stage-1 EL2 page-tables
- Various pKVM cleanups around refcounting and sharing
- A couple of vgic fixes for bugs that would trigger once
the vcpu xarray rework is merged, but not sooner
- Add minimal support for ARMv8.7's PMU extension
- Rework kvm_pgtable initialisation ahead of the NV work
- New selftest for IRQ injection
- Teach selftests about the lack of default IPA space and
page sizes
- Expand sysreg selftest to deal with Pointer Authentication
- The usual bunch of cleanups and doc update
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Everywhere we use kvm_for_each_vpcu(), we use an int as the vcpu
index. Unfortunately, we're about to move rework the iterator,
which requires this to be upgrade to an unsigned long.
Let's bite the bullet and repaint all of it in one go.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Message-Id: <20211116160403.4074052-7-maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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When running a KVM guest hosted on an ARMv8.7 machine, the host
kernel complains that it doesn't know about the architected number
of events.
Fix it by adding the PMUver code corresponding to PMUv3 for ARMv8.7.
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Tested-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211126115533.217903-1-maz@kernel.org
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Move the definition of kvm_arm_pmu_available to pmu-emul.c and, out of
"necessity", hide it behind CONFIG_HW_PERF_EVENTS. Provide a stub for
the key's wrapper, kvm_arm_support_pmu_v3(). Moving the key's definition
out of perf.c will allow a future commit to delete perf.c entirely.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211111020738.2512932-16-seanjc@google.com
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Inspired by commit 254272ce6505 ("kvm: x86: Add memcg accounting to KVM
allocations"), it would be better to make arm64 KVM consistent with
common kvm codes.
The memory allocations of VM scope should be charged into VM process
cgroup, hence change GFP_KERNEL to GFP_KERNEL_ACCOUNT.
There remain a few cases since these allocations are global, not in VM
scope.
Signed-off-by: Jia He <justin.he@arm.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210907123112.10232-3-justin.he@arm.com
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Russell reported that since 5.13, KVM's probing of the PMU has
started to fail on his HW. As it turns out, there is an implicit
ordering dependency between the architectural PMU probing code and
and KVM's own probing. If, due to probe ordering reasons, KVM probes
before the PMU driver, it will fail to detect the PMU and prevent it
from being advertised to guests as well as the VMM.
Obviously, this is one probing too many, and we should be able to
deal with any ordering.
Add a callback from the PMU code into KVM to advertise the registration
of a host CPU PMU, allowing for any probing order.
Fixes: 5421db1be3b1 ("KVM: arm64: Divorce the perf code from oprofile helpers")
Reported-by: "Russell King (Oracle)" <linux@armlinux.org.uk>
Tested-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/YUYRKVflRtUytzy5@shell.armlinux.org.uk
Cc: stable@vger.kernel.org
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* kvm-arm64/misc-5.15:
: Misc improvements for 5.15:
:
: - Account the number of VMID-wide TLB invalidations as
: remote TLB flushes
: - Fix comments in the VGIC code
: - Cleanup the PMU IMPDEF identification
: - Streamline the TGRAN2 usage
: - Avoid advertising a 52bit IPA range for non-64KB configs
: - Avoid spurious signalling when a HW-mapped interrupt is in the
: A+P state on entry, and in the P state on exit, but that the
: physical line is not pending anymore.
: - Bunch of minor cleanups
KVM: arm64: vgic: Resample HW pending state on deactivation
KVM: arm64: vgic: Drop WARN from vgic_get_irq
KVM: arm64: Drop unused REQUIRES_VIRT
KVM: arm64: Drop check_kvm_target_cpu() based percpu probe
KVM: arm64: Drop init_common_resources()
KVM: arm64: Use ARM64_MIN_PARANGE_BITS as the minimum supported IPA
arm64/mm: Add remaining ID_AA64MMFR0_PARANGE_ macros
KVM: arm64: Restrict IPA size to maximum 48 bits on 4K and 16K page size
arm64/mm: Define ID_AA64MMFR0_TGRAN_2_SHIFT
KVM: arm64: perf: Replace '0xf' instances with ID_AA64DFR0_PMUVER_IMP_DEF
KVM: arm64: Fix comments related to GICv2 PMR reporting
KVM: arm64: Count VMID-wide TLB invalidations
arm64/kexec: Test page size support with new TGRAN range values
Signed-off-by: Marc Zyngier <maz@kernel.org>
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ID_AA64DFR0_PMUVER_IMP_DEF which indicate implementation defined PMU, never
actually gets used although there are '0xf' instances scattered all around.
Just do the macro replacement to improve readability.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: linux-perf-users@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: kvmarm@lists.cs.columbia.edu
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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In a KVM guest on arm64, performance counters interrupts have an
unnecessary overhead which slows down execution when using the "perf
record" command and limits the "perf record" sampling period.
The problem is that when a guest VM disables counters by clearing the
PMCR_EL0.E bit (bit 0), KVM will disable all counters defined in
PMCR_EL0 even if they are not enabled in PMCNTENSET_EL0.
KVM disables a counter by calling into the perf framework, in particular
by calling perf_event_create_kernel_counter() which is a time consuming
operation. So, for example, with a Neoverse N1 CPU core which has 6 event
counters and one cycle counter, KVM will always disable all 7 counters
even if only one is enabled.
This typically happens when using the "perf record" command in a guest
VM: perf will disable all event counters with PMCNTENTSET_EL0 and only
uses the cycle counter. And when using the "perf record" -F option with
a high profiling frequency, the overhead of KVM disabling all counters
instead of one on every counter interrupt becomes very noticeable.
The problem is fixed by having KVM disable only counters which are
enabled in PMCNTENSET_EL0. If a counter is not enabled in PMCNTENSET_EL0
then KVM will not enable it when setting PMCR_EL0.E and it will remain
disabled as long as it is not enabled in PMCNTENSET_EL0. So there is
effectively no need to disable a counter when clearing PMCR_EL0.E if it
is not enabled PMCNTENSET_EL0.
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
[maz: moved 'mask' close to the actual user, simplifying the patch]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210712170345.660272-1-alexandre.chartre@oracle.com
Link: https://lore.kernel.org/r/20210719123902.1493805-4-maz@kernel.org
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We always sanitise our PMU sysreg on the write side, so there
is no need to do it on the read side as well.
Drop the unnecessary masking.
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210719123902.1493805-3-maz@kernel.org
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Restoring a guest with an active virtual PMU results in no perf
counters being instanciated on the host side. Not quite what
you'd expect from a restore.
In order to fix this, force a writeback of PMCR_EL0 on the first
run of a vcpu (using a new request so that it happens once the
vcpu has been loaded). This will in turn create all the host-side
counters that were missing.
Reported-by: Jinank Jain <jinankj@amazon.de>
Tested-by: Jinank Jain <jinankj@amazon.de>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/87wnrbylxv.wl-maz@kernel.org
Link: https://lore.kernel.org/r/b53dfcf9bbc4db7f96154b1cd5188d72b9766358.camel@amazon.de
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According to ARM DDI 0487G.a, page D13-3895, setting the PMCR_EL0.P bit to
1 has the following effect:
"Reset all event counters accessible in the current Exception level, not
including PMCCNTR_EL0, to zero."
Similar behaviour is described for AArch32 on page G8-7022. Make it so.
Fixes: c01d6a18023b ("KVM: arm64: pmu: Only handle supported event counters")
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210618105139.83795-1-alexandru.elisei@arm.com
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