From: Jan Kiszka <jan.kiszka@web.de>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
Prasad <prasad@linux.vnet.ibm.com>,
Alan Stern <stern@rowland.harvard.edu>,
Peter Zijlstra <peterz@infradead.org>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Jiri Slaby <jirislaby@gmail.com>, Li Zefan <lizf@cn.fujitsu.com>,
Avi Kivity <avi@redhat.com>, Paul Mackerras <paulus@samba.org>,
Mike Galbraith <efault@gmx.de>,
Masami Hiramatsu <mhiramat@redhat.com>,
Paul Mundt <lethal@linux-sh.org>
Subject: Re: [PATCH 4/6] hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events
Date: Tue, 03 Nov 2009 21:39:16 +0100 [thread overview]
Message-ID: <4AF094F4.9060108@web.de> (raw)
In-Reply-To: <20091103202923.GB4962@nowhere>
[-- Attachment #1: Type: text/plain, Size: 931 bytes --]
Frederic Weisbecker wrote:
> On Tue, Nov 03, 2009 at 09:22:04PM +0100, Jan Kiszka wrote:
>>> Thinking about it, this check should cover every cases:
>>>
>>> if (vcpu->arch.switch_db_regs || __get_cpu_var(dr7) & DR_GLOBAL_ENABLE_MASK)
>>>
>>> If we have __get_cpu_var(dr7) & DR_GLOBAL_ENABLE_MASK, it means there is an
>>> active breakpoint and then we should restore the current state.
>>>
>> And what about (__get_cpu_var(dr7) & DR_GLOBAL_ENABLE_MASK) only? Would
>> you be able to live with unsync'ed hardware and software states?
>>
>> Jan
>>
>
>
> But if the guest has breakpoints activated, the host will inherit
> them, which is really not something we want, assuming vcpu->arch.switch_db_regs
> already protects us about that.
>
Nope, vmx&svm will clear dr7 on vmexit for us. Really, switch_db_regs
should not be needed if we can leave the debug registers clobbered but
disabled behind.
Jan
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 257 bytes --]
next prev parent reply other threads:[~2009-11-03 20:39 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-03 19:11 [GIT PULL v4] hw-breakpoints: Rewrite on top of perf events v4 Frederic Weisbecker
2009-11-03 19:11 ` [PATCH 1/6] perf/core: Provide a kernel-internal interface to get to performance counters Frederic Weisbecker
2009-11-03 19:11 ` [PATCH 2/6] x86/hw-breakpoints: Actually flush thread breakpoints in flush_thread() Frederic Weisbecker
2009-11-03 19:11 ` [PATCH 3/6] perf/core: Add a callback to perf events Frederic Weisbecker
2009-11-03 19:11 ` [PATCH 4/6] hw-breakpoints: Rewrite the hw-breakpoints layer on top of " Frederic Weisbecker
2009-11-03 19:58 ` Jan Kiszka
2009-11-03 20:15 ` Frederic Weisbecker
2009-11-03 20:22 ` Jan Kiszka
2009-11-03 20:29 ` Frederic Weisbecker
2009-11-03 20:39 ` Jan Kiszka [this message]
2009-11-03 20:45 ` Frederic Weisbecker
2009-11-04 23:59 ` Paul Mackerras
2009-11-05 6:00 ` K.Prasad
2009-11-05 11:00 ` Paul Mackerras
2009-11-05 11:09 ` Frederic Weisbecker
2009-11-07 10:03 ` Paul Mackerras
2009-11-07 19:52 ` Frederic Weisbecker
2009-11-05 11:03 ` Paul Mackerras
2009-11-05 11:11 ` Frederic Weisbecker
2009-11-05 15:34 ` K.Prasad
2009-11-05 21:06 ` Frederic Weisbecker
2009-11-08 17:32 ` K.Prasad
2009-11-12 15:42 ` Frederic Weisbecker
2009-11-03 19:11 ` [PATCH 5/6] hw-breakpoints: Arbitrate access to pmu following registers constraints Frederic Weisbecker
2009-11-05 10:58 ` Paul Mackerras
2009-11-05 11:24 ` Frederic Weisbecker
2009-11-08 20:56 ` Benjamin Herrenschmidt
2009-11-12 15:54 ` Frederic Weisbecker
2009-11-12 20:00 ` Benjamin Herrenschmidt
2009-11-14 13:34 ` Frederic Weisbecker
2009-11-03 19:11 ` [PATCH 6/6] ksym_tracer: Remove KSYM_SELFTEST_ENTRY Frederic Weisbecker
2009-11-05 14:13 ` [GIT PULL v4] hw-breakpoints: Rewrite on top of perf events v4 K.Prasad
2009-11-05 20:30 ` Frederic Weisbecker
-- strict thread matches above, loose matches on Subject: below --
2009-10-24 14:16 [GIT PULL v2] hw-breakpoints: Rewrite on top of perf events Frederic Weisbecker
2009-10-24 14:16 ` [PATCH 4/6] hw-breakpoints: Rewrite the hw-breakpoints layer " Frederic Weisbecker
2009-10-24 16:19 ` Jan Kiszka
2009-10-25 23:31 ` Frederic Weisbecker
2009-10-26 8:17 ` Jan Kiszka
2009-11-01 21:09 ` Frederic Weisbecker
2009-11-01 22:09 ` Jan Kiszka
2009-11-01 22:49 ` Frederic Weisbecker
2009-11-01 23:37 ` Frederic Weisbecker
2009-11-02 7:45 ` Jan Kiszka
2009-11-02 13:04 ` Frederic Weisbecker
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=4AF094F4.9060108@web.de \
--to=jan.kiszka@web.de \
--cc=acme@redhat.com \
--cc=avi@redhat.com \
--cc=efault@gmx.de \
--cc=fweisbec@gmail.com \
--cc=jirislaby@gmail.com \
--cc=lethal@linux-sh.org \
--cc=linux-kernel@vger.kernel.org \
--cc=lizf@cn.fujitsu.com \
--cc=mhiramat@redhat.com \
--cc=mingo@elte.hu \
--cc=paulus@samba.org \
--cc=peterz@infradead.org \
--cc=prasad@linux.vnet.ibm.com \
--cc=rostedt@goodmis.org \
--cc=stern@rowland.harvard.edu \
/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