From: Marc Zyngier <maz@kernel.org>
To: Vincent Donnefort <vdonnefort@google.com>
Cc: rostedt@goodmis.org, mhiramat@kernel.org,
mathieu.desnoyers@efficios.com,
linux-trace-kernel@vger.kernel.org, oliver.upton@linux.dev,
joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com,
kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
jstultz@google.com, qperret@google.com, will@kernel.org,
aneesh.kumar@kernel.org, kernel-team@android.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v9 29/30] KVM: arm64: Add selftest event support to nVHE/pKVM hyp
Date: Fri, 23 Jan 2026 12:47:15 +0000 [thread overview]
Message-ID: <86o6mkbing.wl-maz@kernel.org> (raw)
In-Reply-To: <aXNmKpHqVw93BegX@google.com>
On Fri, 23 Jan 2026 12:14:34 +0000,
Vincent Donnefort <vdonnefort@google.com> wrote:
>
> On Wed, Jan 07, 2026 at 03:40:22PM +0000, Marc Zyngier wrote:
> > On Tue, 02 Dec 2025 09:36:22 +0000,
> > Vincent Donnefort <vdonnefort@google.com> wrote:
> > >
> > Not strictly related to this patch, but I find that the trace itself
> > lacks context. For example:
> >
> > [001] 323.847422: hyp_enter reason=hvc
> > [001] 323.847423: hyp_exit reason=eret_host
> > [001] 323.847688: hyp_enter reason=hvc
> > [001] 323.847688: hyp_exit reason=eret_host
> > [001] 323.847706: hyp_enter reason=hvc
> > [001] 323.847707: hyp_exit reason=eret_host
> > [001] 323.847722: hyp_enter reason=hvc
> > [001] 323.847723: hyp_exit reason=eret_host
> >
> > That's all fine as long as I'm dealing with a single guest, or even
> > with a single vcpu. Trying to trace multiple guests, or even multiple
> > vcpus makes the whole thing completely unusable, because I have no
> > idea what I'm looking at.
> >
> > To make this useful, having some context provided by the host really
> > is required.
>
> I could add to the event header the VM pid related to the currently loaded vCPU
> (if any). I can access it easily with host_kvm->userspace_pid. WDYS?
It really should be the thread name, just like we already have for the
kernel tracing. For example:
vgic_irq-2007 [005] ..... 180926.476735: kvm_sys_access: PC: 4119e4 SYS_ICC_DIR_EL1 (3,0,12,11,1) write
vgic_irq-2010 [005] ..... 180926.534771: kvm_sys_access: PC: 40254c SYS_CNTV_CVAL_EL0 (3,3,14,3,2) write
vgic_irq-2010 [005] ..... 180926.534777: kvm_sys_access: PC: 402554 SYS_CNTV_CTL_EL0 (3,3,14,3,1) write
vgic_irq-2010 [005] ..... 180926.534789: kvm_sys_access: PC: 4025b8 SYS_CNTV_CTL_EL0 (3,3,14,3,1) write
vgic_irq-2011 [010] ..... 180926.534790: kvm_sys_access: PC: 40254c SYS_CNTV_CVAL_EL0 (3,3,14,3,2) write
vgic_irq-2010 [005] ..... 180926.534793: kvm_sys_access: PC: 4119e4 SYS_ICC_DIR_EL1 (3,0,12,11,1) write
This is a single guest, with concurrent vcpus. I'd like to be able to
correlate that with what the hypervisor tracing outputs. At the very
least the thread's PID. But the VM itself is pretty much irrelevant.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2026-01-23 12:47 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-02 9:35 [PATCH v9 00/30] Tracefs support for pKVM Vincent Donnefort
2025-12-02 9:35 ` [PATCH v9 01/30] ring-buffer: Add page statistics to the meta-page Vincent Donnefort
2025-12-02 9:35 ` [PATCH v9 02/30] ring-buffer: Store bpage pointers into subbuf_ids Vincent Donnefort
2025-12-02 9:35 ` [PATCH v9 03/30] ring-buffer: Introduce ring-buffer remotes Vincent Donnefort
2025-12-02 9:35 ` [PATCH v9 04/30] ring-buffer: Add non-consuming read for " Vincent Donnefort
2025-12-02 9:35 ` [PATCH v9 05/30] tracing: Introduce trace remotes Vincent Donnefort
2025-12-02 9:35 ` [PATCH v9 06/30] tracing: Add reset to " Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 07/30] tracing: Add non-consuming read " Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 08/30] tracing: Add init callback " Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 09/30] tracing: Add events " Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 10/30] tracing: Add events/ root files " Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 11/30] tracing: Add helpers to create trace remote events Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 12/30] ring-buffer: Export buffer_data_page and macros Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 13/30] tracing: Introduce simple_ring_buffer Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 14/30] tracing: Add a trace remote module for testing Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 15/30] tracing: selftests: Add trace remote tests Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 16/30] Documentation: tracing: Add tracing remotes Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 17/30] tracing: load/unload page callbacks for simple_ring_buffer Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 18/30] tracing: Check for undefined symbols in simple_ring_buffer Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 19/30] KVM: arm64: Add PKVM_DISABLE_STAGE2_ON_PANIC Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 20/30] KVM: arm64: Add clock support to nVHE/pKVM hyp Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 21/30] KVM: arm64: Initialise hyp_nr_cpus for nVHE hyp Vincent Donnefort
2026-01-07 13:45 ` Marc Zyngier
2025-12-02 9:36 ` [PATCH v9 22/30] KVM: arm64: Support unaligned fixmap in the pKVM hyp Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 23/30] KVM: arm64: Add tracing capability for the nVHE/pKVM hyp Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 24/30] KVM: arm64: Add trace remote " Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 25/30] KVM: arm64: Sync boot clock with " Vincent Donnefort
2026-01-07 14:23 ` Marc Zyngier
2026-01-23 12:12 ` Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 26/30] KVM: arm64: Add trace reset to " Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 27/30] KVM: arm64: Add event support to the nVHE/pKVM hyp and trace remote Vincent Donnefort
2025-12-02 9:36 ` [PATCH v9 28/30] KVM: arm64: Add hyp_enter/hyp_exit events to nVHE/pKVM hyp Vincent Donnefort
2026-01-07 14:37 ` Marc Zyngier
2026-01-07 16:36 ` Steven Rostedt
2025-12-02 9:36 ` [PATCH v9 29/30] KVM: arm64: Add selftest event support " Vincent Donnefort
2026-01-07 15:40 ` Marc Zyngier
2026-01-23 12:14 ` Vincent Donnefort
2026-01-23 12:21 ` Vincent Donnefort
2026-01-23 12:47 ` Marc Zyngier
2026-01-23 12:47 ` Marc Zyngier [this message]
2025-12-02 9:36 ` [PATCH v9 30/30] tracing: selftests: Add hypervisor trace remote tests Vincent Donnefort
2026-01-07 16:00 ` [PATCH v9 00/30] Tracefs support for pKVM Marc Zyngier
2026-01-07 16:59 ` Steven Rostedt
2026-01-16 10:08 ` Marc Zyngier
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