From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Yi Wang <wang.yi59@zte.com.cn>
Cc: pbonzini@redhat.com, rkrcmar@redhat.com, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] [next] KVM: lapic: allow set apic debug dynamically
Date: Thu, 9 May 2019 13:20:00 -0700 [thread overview]
Message-ID: <20190509201959.GA12810@linux.intel.com> (raw)
In-Reply-To: <1557398877-32750-1-git-send-email-wang.yi59@zte.com.cn>
On Thu, May 09, 2019 at 06:47:57PM +0800, Yi Wang wrote:
> There are many functions invoke apic_debug(), which is defined
> a null function by default, and that's incovenient for debuging
> lapic.
>
> This patch allows setting apic debug according to add a apic_dbg
> parameter of kvm.
>
> Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
> ---
> v2: change apic_dbg to bool and tag __read_mostly. Thanks to Sean.
>
> arch/x86/kvm/lapic.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 9bf70cf..0827e7c 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -54,8 +54,13 @@
> #define PRIu64 "u"
> #define PRIo64 "o"
>
> +static bool apic_dbg __read_mostly;
> +module_param(apic_dbg, bool, 0644);
Probably don't need to shorten "debug".
> +
> /* #define apic_debug(fmt,arg...) printk(KERN_WARNING fmt,##arg) */
> -#define apic_debug(fmt, arg...) do {} while (0)
> +#define apic_debug(fmt, arg...) do { if (apic_dbg) \
> + printk(KERN_DEBUG fmt, ##arg); \
> +} while (0)
Pulling in your comment regarding sched_debug and noirqdebug...
On Thu, May 09, 2019 at 08:29:38AM +0800, wang.yi59@zte.com.cn wrote:
> Also, we have some similar parameters already, such like sched_debug,
> noirqdebug :)
The IRQ debug hook is a completely different beast than the APIC debug
messages.
sched_debug is a much better comparison. The param only exists if
CONFIG_SCHED_DEBUG=y, which is "default y" but "depends on DEBUG_KERNEL".
That seems like the route to go if we want the ability to toggle APIC
debugging at runtime. And if we go with an all encompassing config,
e.g. CONFIG_KVM_DEBUG, we can use it to wrap x86/mmu.c's debug param as
well (and rename it to mmu_debug).
>
> /* 14 is the version for Xeon and Pentium 8.4.8*/
> #define APIC_VERSION (0x14UL | ((KVM_APIC_LVT_NUM - 1) << 16))
> --
> 1.8.3.1
>
next prev parent reply other threads:[~2019-05-09 20:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-09 10:47 [PATCH v2] [next] KVM: lapic: allow set apic debug dynamically Yi Wang
2019-05-09 20:20 ` Sean Christopherson [this message]
[not found] ` <201905101254211413423@zte.com.cn>
2019-05-10 17:49 ` Sean Christopherson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190509201959.GA12810@linux.intel.com \
--to=sean.j.christopherson@intel.com \
--cc=bp@alien8.de \
--cc=hpa@zytor.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=pbonzini@redhat.com \
--cc=rkrcmar@redhat.com \
--cc=tglx@linutronix.de \
--cc=wang.yi59@zte.com.cn \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).