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Re: [XEN][PATCH] xen: make VMTRACE support optional
- To: Jan Beulich <jbeulich@xxxxxxxx>, Teddy Astie <teddy.astie@xxxxxxxxxx>
- From: Grygorii Strashko <grygorii_strashko@xxxxxxxx>
- Date: Fri, 7 Nov 2025 17:47:40 +0200
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Julien Grall <julien@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Tamas K Lengyel <tamas@xxxxxxxxxxxxx>, Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>, Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>, Penny Zheng <Penny.Zheng@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Fri, 07 Nov 2025 15:47:49 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
Hi
On 06.11.25 16:09, Jan Beulich wrote:
On 06.11.2025 14:50, Grygorii Strashko wrote:
On 06.11.25 14:00, Jan Beulich wrote:
On 31.10.2025 22:20, Grygorii Strashko wrote:
--- a/xen/Kconfig.debug
+++ b/xen/Kconfig.debug
@@ -155,4 +155,19 @@ config DEBUG_INFO
"make install-xen" for installing xen.efi, stripping needs to be
done outside the Xen build environment).
+config HAS_VMTRACE
+ bool
+
+config VMTRACE
+ bool "HW VM tracing support"
+ depends on HAS_VMTRACE
+ default y
+ help
+ Enables HW VM tracing support which allows to configure HW processor
+ features (vmtrace_op) to enable capturing information about software
+ execution using dedicated hardware facilities with minimal interference
+ to the software being traced. The trace date can be retrieved using
buffer
Nit: s/date/data/
+ shared between Xen and domain
+ (see XENMEM_acquire_resource(XENMEM_resource_vmtrace_buf)).
+
I was actually meaning to ask that "VMX only" should somehow be mentioned here,
but then I noticed this is an arch-independent location.
Right, Arch code advertise VMTRACE support with HAS_VMTRACE.
In this particular case:
config INTEL_VMX
...
select HAS_VMTRACE
I'm not quite sure we want it like this (just yet).
?
To rephrase the question: Are we expecting anything other than VMX to support
VMTRACE any time soon?
That's I do not know.
I assume your point is similar to what Teddy noted [1].
I think vmtrace code can be consolidate, but question is on what level(s):
only:
xen/arch/x86/hvm/vmx/
|- vmtrace.c
or:
xen/arch/x86/hvm
|- vmtrace.c
<- vmtrace_alloc/free_buffer(), acquire_vmtrace_buf(), do_vmtrace_op()
xen/arch/x86/hvm/vmx/
|- vmtrace.c
it will require more work comparing to the current change.
[1] https://patchwork.kernel.org/comment/26637627/
--
Best regards,
-grygorii
|
