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From: Andi Kleen <ak@linux.intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Lai Jiangshan <jiangshanlai+lkml@gmail.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Uros Bizjak <ubizjak@gmail.com>,
	Andy Lutomirski <luto@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH v2 2/2] KVM: VMX: Invoke NMI handler via indirect call instead of INTn
Date: Mon, 26 Apr 2021 07:51:04 -0700	[thread overview]
Message-ID: <20210426145104.GW1401198@tassilo.jf.intel.com> (raw)
In-Reply-To: <bb2c2d93-8046-017a-5711-c61c8f1a4c09@redhat.com>

> > The original code "int $2" can provide the needed CPU-hidden-NMI-masked
> > when entering #NMI, but I doubt it about this change.
> 
> How would "int $2" block NMIs?  The hidden effect of this change (and I
> should have reviewed better the effect on the NMI entry code) is that the
> call will not use the IST anymore.

My understanding is that int $2 does not block NMIs.

So reentries might have been possible.

-Andi

  parent reply	other threads:[~2021-04-26 14:51 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-15 19:15 [PATCH v2 0/2] KVM: VMX: Clean up IRQ/NMI handling Sean Christopherson
2020-09-15 19:15 ` [PATCH v2 1/2] KVM: VMX: Move IRQ invocation to assembly subroutine Sean Christopherson
2020-09-15 19:27   ` Josh Poimboeuf
2020-09-15 19:38   ` Uros Bizjak
2020-09-15 19:15 ` [PATCH v2 2/2] KVM: VMX: Invoke NMI handler via indirect call instead of INTn Sean Christopherson
2021-04-26  9:33   ` Lai Jiangshan
2021-04-26 10:40     ` Paolo Bonzini
2021-04-26 11:44       ` Maxim Levitsky
2021-04-26 13:59         ` Steven Rostedt
2021-04-26 14:51       ` Andi Kleen [this message]
2021-04-26 15:09         ` Andy Lutomirski
2021-04-27  0:54       ` Lai Jiangshan
2021-04-27  1:00         ` Steven Rostedt
2021-04-27  7:05         ` Paolo Bonzini
2021-04-30  2:56           ` Lai Jiangshan
2020-09-22 13:38 ` [PATCH v2 0/2] KVM: VMX: Clean up IRQ/NMI handling Paolo Bonzini

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