From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Xiaoyao Li <xiaoyao.li@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Paolo Bonzini <pbonzini@redhat.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org
Subject: Re: [PATCH 2/2] KVM: VMX: Extend VMX's #AC handding
Date: Fri, 31 Jan 2020 13:04:24 -0800 [thread overview]
Message-ID: <20200131210424.GG18946@linux.intel.com> (raw)
In-Reply-To: <5CD544A4-291A-47A1-80D1-F77FE0444925@amacapital.net>
On Fri, Jan 31, 2020 at 12:57:51PM -0800, Andy Lutomirski wrote:
>
> > On Jan 31, 2020, at 12:18 PM, Sean Christopherson <sean.j.christopherson@intel.com> wrote:
> >
> > This is essentially what I proposed a while back. KVM would allow enabling
> > split-lock #AC in the guest if and only if SMT is disabled or the enable bit
> > is per-thread, *or* the host is in "warn" mode (can live with split-lock #AC
> > being randomly disabled/enabled) and userspace has communicated to KVM that
> > it is pinning vCPUs.
>
> How about covering the actual sensible case: host is set to fatal? In this
> mode, the guest gets split lock detection whether it wants it or not. How do
> we communicate this to the guest?
KVM doesn't advertise split-lock #AC to the guest and returns -EFAULT to the
userspace VMM if the guest triggers a split-lock #AC.
Effectively the same behavior as any other userspace process, just that KVM
explicitly returns -EFAULT instead of the process getting a SIGBUS.
next prev parent reply other threads:[~2020-01-31 21:04 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-30 12:19 [PATCH 0/2] kvm: split_lock: Fix emulator and extend #AC handler Xiaoyao Li
2020-01-30 12:19 ` [PATCH 1/2] KVM: x86: Emulate split-lock access as a write Xiaoyao Li
2020-01-30 12:31 ` David Laight
2020-01-30 15:16 ` Andy Lutomirski
2020-01-31 20:01 ` Sean Christopherson
2020-02-04 14:47 ` Vitaly Kuznetsov
2020-02-10 21:59 ` Sean Christopherson
2020-01-30 12:19 ` [PATCH 2/2] KVM: VMX: Extend VMX's #AC handding Xiaoyao Li
2020-01-30 15:18 ` Andy Lutomirski
2020-01-30 16:29 ` Xiaoyao Li
2020-01-30 17:16 ` Andy Lutomirski
2020-01-31 7:22 ` Xiaoyao Li
2020-01-31 15:37 ` Andy Lutomirski
2020-01-31 17:47 ` Xiaoyao Li
2020-01-31 20:17 ` Sean Christopherson
2020-01-31 20:57 ` Andy Lutomirski
2020-01-31 21:04 ` Sean Christopherson [this message]
2020-01-31 21:33 ` Andy Lutomirski
2020-02-01 16:58 ` Xiaoyao Li
2020-02-01 17:56 ` Andy Lutomirski
2020-02-02 4:33 ` Xiaoyao Li
2020-02-03 18:49 ` Andy Lutomirski
2020-02-04 6:03 ` Sean Christopherson
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