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From: Alexandru Elisei <alexandru.elisei@arm.com>
To: maz@kernel.org, james.morse@arm.com, suzuki.poulose@arm.com,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, will@kernel.org,
	linux-kernel@vger.kernel.org
Subject: [RFC PATCH v4 38/39] KVM: arm64: Make CONFIG_KVM_ARM_SPE depend on !CONFIG_NUMA_BALANCING
Date: Wed, 25 Aug 2021 17:18:14 +0100	[thread overview]
Message-ID: <20210825161815.266051-39-alexandru.elisei@arm.com> (raw)
In-Reply-To: <20210825161815.266051-1-alexandru.elisei@arm.com>

Automatic NUMA balancing is a performance strategy that Linux uses to
reduce the cost associated with memory accesses by having a task use
the memory closest to the NUMA node where the task is executing. This is
accomplished by triggering periodic page faults to examine the memory
location that a task uses, and decide if page migration is necessary.

The periodic page faults that drive automatic NUMA balancing are triggered
by clearing permissions on certain pages from the task's address space.
Clearing the permissions invokes mmu_notifier_invalidate_range_start(),
which causes guest memory from being unmapped from stage 2. As a result,
SPE can start reporting stage 2 faults, which KVM has no way of handling.

Make CONFIG_KVM_ARM_SPE depend on !CONFIG_NUMA_BALANCING to keep SPE usable
for a guest.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 arch/arm64/kvm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index c6ad5a05efb3..1ea34eb29fb4 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -48,7 +48,7 @@ source "virt/kvm/Kconfig"
 
 config KVM_ARM_SPE
 	bool "Virtual Statistical Profiling Extension (SPE) support"
-	depends on ARM_SPE_PMU=y
+	depends on ARM_SPE_PMU=y && !NUMA_BALANCING
 	default y
 	help
 	  Adds support for Statistical Profiling Extension (SPE) in virtual
-- 
2.33.0

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  parent reply	other threads:[~2021-08-25 16:20 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-25 16:17 [RFC PATCH v4 00/39] KVM: arm64: Add Statistical Profiling Extension (SPE) support Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 01/39] KVM: arm64: Make lock_all_vcpus() available to the rest of KVM Alexandru Elisei
2021-09-22 10:39   ` Suzuki K Poulose
2021-08-25 16:17 ` [RFC PATCH v4 02/39] KVM: arm64: Add lock/unlock memslot user API Alexandru Elisei
2021-10-18  9:04   ` Suzuki K Poulose
2021-10-18 14:09     ` Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 03/39] KVM: arm64: Implement the memslot lock/unlock functionality Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 04/39] KVM: arm64: Defer CMOs for locked memslots until a VCPU is run Alexandru Elisei
2021-10-17 11:43   ` Marc Zyngier
2021-10-18 12:56     ` Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 05/39] KVM: arm64: Perform CMOs on locked memslots when userspace resets VCPUs Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 06/39] KVM: arm64: Delay tag scrubbing for locked memslots until a VCPU runs Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 07/39] KVM: arm64: Unlock memslots after stage 2 tables are freed Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 08/39] KVM: arm64: Deny changes to locked memslots Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 09/39] KVM: Add kvm_warn{,_ratelimited} macros Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 10/39] KVM: arm64: Print a warning for unexpected faults on locked memslots Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 11/39] KVM: arm64: Allow userspace to lock and unlock memslots Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 12/39] KVM: arm64: Add the KVM_ARM_VCPU_SUPPORTED_CPUS VCPU ioctl Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 13/39] KVM: arm64: Add CONFIG_KVM_ARM_SPE Kconfig option Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 14/39] KVM: arm64: Add SPE capability and VCPU feature Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 15/39] drivers/perf: Expose the cpumask of CPUs that support SPE Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 16/39] KVM: arm64: Make SPE available when at least one CPU supports it Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 17/39] KVM: arm64: Set the VCPU SPE feature bit when SPE is available Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 18/39] KVM: arm64: Expose SPE version to guests Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 19/39] KVM: arm64: Do not emulate SPE on CPUs which don't have SPE Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 20/39] KVM: arm64: Add a new VCPU device control group for SPE Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 21/39] KVM: arm64: Add SPE VCPU device attribute to set the interrupt number Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 22/39] KVM: arm64: Add SPE VCPU device attribute to initialize SPE Alexandru Elisei
2021-08-25 16:17 ` [RFC PATCH v4 23/39] KVM: arm64: VHE: Clear MDCR_EL2.E2PB in vcpu_put() Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 24/39] KVM: arm64: debug: Configure MDCR_EL2 when a VCPU has SPE Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 25/39] KVM: arm64: Move the write to MDCR_EL2 out of __activate_traps_common() Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 26/39] KVM: arm64: VHE: Change MDCR_EL2 at world switch if VCPU has SPE Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 27/39] KVM: arm64: Add SPE system registers to VCPU context Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 28/39] KVM: arm64: nVHE: Save PMSCR_EL1 to the host context Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 29/39] KVM: arm64: Rename DEBUG_STATE_SAVE_SPE -> DEBUG_SAVE_SPE_BUFFER flags Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 30/39] KVM: arm64: nVHE: Context switch SPE state if VCPU has SPE Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 31/39] KVM: arm64: VHE: " Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 32/39] KVM: arm64: Save/restore PMSNEVFR_EL1 on VCPU put/load Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 33/39] KVM: arm64: Allow guest to use physical timestamps if perfmon_capable() Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 34/39] KVM: arm64: Emulate SPE buffer management interrupt Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 35/39] KVM: arm64: Add an userspace API to stop a VCPU profiling Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 36/39] KVM: arm64: Implement " Alexandru Elisei
2021-08-25 16:18 ` [RFC PATCH v4 37/39] KVM: arm64: Add PMSIDR_EL1 to the SPE register context Alexandru Elisei
2021-08-25 16:18 ` Alexandru Elisei [this message]
2021-08-25 16:18 ` [RFC PATCH v4 39/39] KVM: arm64: Allow userspace to enable SPE for guests Alexandru Elisei
2021-09-22 10:11 ` [RFC PATCH v4 00/39] KVM: arm64: Add Statistical Profiling Extension (SPE) support Suzuki K Poulose
2021-09-23 15:12   ` Alexandru Elisei

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