From: Andy Lutomirski <luto@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Xiaoyao Li <xiaoyao.li@intel.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
X86 ML <x86@kernel.org>, kvm list <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
David Laight <David.Laight@aculab.com>
Subject: Re: [PATCH v2 5/6] kvm: x86: Emulate MSR IA32_CORE_CAPABILITIES
Date: Mon, 10 Feb 2020 19:52:13 -0800 [thread overview]
Message-ID: <CALCETrUAsUzqLhhNkLSC2612odskjqPQvj4uXgBOaoBGoCQD0A@mail.gmail.com> (raw)
In-Reply-To: <20200204093725.GC14879@hirez.programming.kicks-ass.net>
On Tue, Feb 4, 2020 at 1:37 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Tue, Feb 04, 2020 at 05:19:26PM +0800, Xiaoyao Li wrote:
>
> > > > + case MSR_IA32_CORE_CAPS:
> > > > + if (!msr_info->host_initiated)
> > >
> > > Shouldn't @data be checked against kvm_get_core_capabilities()?
> >
> > Maybe it's for the case that userspace might have the ability to emulate SLD
> > feature? And we usually let userspace set whatever it wants, e.g.,
> > ARCH_CAPABILITIES.
>
> If the 'sq_misc.split_lock' event is sufficiently accurate, I suppose
> the host could use that to emulate the feature at the cost of one
> counter used.
I would be impressed if the event were to fire before executing the
offending split lock. Wouldn't the best possible result be for it to
fire with RIP pointing to the *next* instruction? This seems like it
could be quite confusing to a guest.
next prev parent reply other threads:[~2020-02-11 3:52 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-03 15:16 [PATCH v2 0/6] kvm/split_lock: Add feature split lock detection support in kvm Xiaoyao Li
2020-02-03 15:16 ` [PATCH v2 1/6] x86/split_lock: Add and export get_split_lock_detect_state() Xiaoyao Li
2020-02-03 21:45 ` Sean Christopherson
2020-02-03 15:16 ` [PATCH v2 2/6] x86/split_lock: Add and export split_lock_detect_set() Xiaoyao Li
2020-02-03 15:16 ` [PATCH v2 3/6] kvm: x86: Emulate split-lock access as a write Xiaoyao Li
2020-02-03 20:54 ` Sean Christopherson
2020-02-04 2:55 ` Xiaoyao Li
2020-02-11 12:20 ` Paolo Bonzini
2020-02-11 13:22 ` Thomas Gleixner
2020-02-11 13:34 ` Paolo Bonzini
2020-02-11 14:02 ` Xiaoyao Li
2020-02-11 14:34 ` David Laight
2020-02-27 0:11 ` Sean Christopherson
2020-03-12 11:42 ` Xiaoyao Li
2020-03-12 15:00 ` Paolo Bonzini
2020-02-03 15:16 ` [PATCH v2 4/6] kvm: vmx: Extend VMX's #AC handding for split lock in guest Xiaoyao Li
2020-02-03 21:14 ` Sean Christopherson
2020-02-04 6:46 ` Xiaoyao Li
2020-02-10 21:30 ` Sean Christopherson
2020-02-03 15:16 ` [PATCH v2 5/6] kvm: x86: Emulate MSR IA32_CORE_CAPABILITIES Xiaoyao Li
2020-02-03 21:43 ` Sean Christopherson
2020-02-04 9:19 ` Xiaoyao Li
2020-02-04 9:37 ` Peter Zijlstra
2020-02-11 3:52 ` Andy Lutomirski [this message]
2020-02-11 12:38 ` Peter Zijlstra
2020-02-03 15:16 ` [PATCH v2 6/6] x86: vmx: virtualize split lock detection Xiaoyao Li
2020-02-03 15:58 ` Xiaoyao Li
2020-02-03 18:52 ` Andy Lutomirski
2020-02-03 21:42 ` Sean Christopherson
2020-02-04 2:52 ` Xiaoyao Li
2020-02-04 5:35 ` Sean Christopherson
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