From: Andi Kleen <ak@linux.intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Wanpeng Li" <kernellwp@gmail.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Wanpeng Li" <wanpeng.li@hotmail.com>,
"Jim Mattson" <jmattson@google.com>
Subject: Re: [PATCH] KVM: VMX: Cache IA32_DEBUGCTL in memory
Date: Wed, 29 Nov 2017 14:45:21 -0800 [thread overview]
Message-ID: <20171129224521.GF3070@tassilo.jf.intel.com> (raw)
In-Reply-To: <5045320c-3036-4e08-140e-4bb5cf78be24@redhat.com>
On Wed, Nov 29, 2017 at 11:26:30PM +0100, Paolo Bonzini wrote:
> On 29/11/2017 19:20, Andi Kleen wrote:
> > But I haven't looked too closely, but I suspect you'll clobber global
> > kernel debugger state this way.
>
> I checked all callers of update_debugctlmsr, and couldn't find any that
> could run asynchronously while KVM is caching the value. For example
> __switch_to_xtra would always run before the sched_in notifier.
True. It would only be a problem if the debugger supported branch stepping
or LBRs, which it doesn't seem to currently.
-Andi
prev parent reply other threads:[~2017-11-29 22:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-29 6:07 [PATCH] KVM: VMX: Cache IA32_DEBUGCTL in memory Wanpeng Li
2017-11-29 8:48 ` Paolo Bonzini
2017-11-29 8:51 ` Wanpeng Li
2017-11-29 9:13 ` Paolo Bonzini
2017-11-29 9:20 ` Wanpeng Li
2017-11-29 18:20 ` Andi Kleen
2017-11-29 19:05 ` Jim Mattson
2017-11-29 20:56 ` Andi Kleen
2017-11-29 22:26 ` Paolo Bonzini
2017-11-29 22:45 ` Andi Kleen [this message]
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