From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: tglx@linutronix.de, luto@amacapital.net,
linux-kernel@vger.kernel.org, x86@kernel.org,
Lai Jiangshan <laijs@linux.alibaba.com>,
andrew.cooper3@citrix.com, daniel.thompson@linaro.org,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH 4/6] x86/entry: Optimize local_db_save() for virt
Date: Fri, 29 May 2020 10:24:49 -0700 [thread overview]
Message-ID: <20200529172448.GA1074@linux.intel.com> (raw)
In-Reply-To: <20200528202328.588432451@infradead.org>
On Thu, May 28, 2020 at 10:19:41PM +0200, Peter Zijlstra wrote:
> static int arch_bp_generic_len(int x86_len)
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -3027,6 +3027,8 @@ static int nested_vmx_check_vmentry_hw(s
>
> /*
> * VMExit clears RFLAGS.IF and DR7, even on a consistency check.
> + * XXX how is this not broken? access to cpu_dr7 ought to be with
> + * IRQs disabled.
Ah, it's simply broken. This code is conditional on a module param that's
off by default, i.e. it's not run widely, and odds are intersection with
debugging is rare.
Moving local_irq_enable() below the DR7 restoration is not an issue.
Maybe also add lockdep_assert_irqs_disabled() to hw_breakpoint_restore() or
hw_breakpoint_active()?
> */
> local_irq_enable();
> if (hw_breakpoint_active())
>
>
next prev parent reply other threads:[~2020-05-29 17:34 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-28 20:19 [PATCH 0/6] x86/entry: disallow #DB more Peter Zijlstra
2020-05-28 20:19 ` [PATCH 1/6] x86/entry: Introduce local_db_{save,restore}() Peter Zijlstra
2020-05-28 20:52 ` Andrew Cooper
2020-05-28 21:15 ` Peter Zijlstra
2020-05-28 21:33 ` Peter Zijlstra
2020-05-29 17:28 ` Andy Lutomirski
2020-05-29 19:02 ` Peter Zijlstra
2020-05-28 21:36 ` Andrew Cooper
2020-05-28 20:19 ` [PATCH 2/6] x86/entry, nmi: Disable #DB Peter Zijlstra
2020-05-28 20:19 ` [PATCH 3/6] x86/entry, mce: Disallow #DB during #MC Peter Zijlstra
2020-05-28 20:19 ` [PATCH 4/6] x86/entry: Optimize local_db_save() for virt Peter Zijlstra
2020-05-29 17:24 ` Sean Christopherson [this message]
2020-05-28 20:19 ` [PATCH 5/6] x86/entry: Remove debug IDT frobbing Peter Zijlstra
2020-05-28 20:19 ` [RFC][PATCH 6/6] x86/entry: Remove DBn stacks Peter Zijlstra
2020-05-28 22:35 ` Lai Jiangshan
2020-05-28 22:37 ` Peter Zijlstra
2020-05-28 22:42 ` [PATCH 0/6] x86/entry: disallow #DB more Lai Jiangshan
2020-05-28 22:48 ` Peter Zijlstra
2020-05-28 23:05 ` Lai Jiangshan
2020-05-29 8:00 ` Peter Zijlstra
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=20200529172448.GA1074@linux.intel.com \
--to=sean.j.christopherson@intel.com \
--cc=andrew.cooper3@citrix.com \
--cc=daniel.thompson@linaro.org \
--cc=laijs@linux.alibaba.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=luto@kernel.org \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--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).