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From: Paolo Bonzini <pbonzini@redhat.com>
To: Maxim Levitsky <mlevitsk@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	linux-kernel@vger.kernel.org
Cc: Lai Jiangshan <laijs@linux.alibaba.com>,
	Sean Christopherson <seanjc@google.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Andi Kleen <ak@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Uros Bizjak <ubizjak@gmail.com>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Alexandre Chartre <alexandre.chartre@oracle.com>,
	Juergen Gross <jgross@suse.com>, Joerg Roedel <jroedel@suse.de>,
	Jian Cai <caij2003@gmail.com>
Subject: Re: [PATCH] KVM/VMX: Invoke NMI non-IST entry instead of IST entry
Date: Tue, 4 May 2021 23:12:12 +0200	[thread overview]
Message-ID: <ae801539-592a-af9a-55a1-3a4b8309ff1e@redhat.com> (raw)
In-Reply-To: <44e20d7cdbf0ffdb7d9dce7d480f86a6f14d16c1.camel@redhat.com>

On 04/05/21 23:05, Maxim Levitsky wrote:
> Does this mean that we still rely on hardware NMI masking to be activated?

No, the NMI code already handles reentrancy at both the assembly and C 
levels.

> Or in other words, that is we still can't have an IRET between VM exit and
> the entry to the NMI handler?

No, because NMIs are not masked on VM exit.  This in fact makes things 
potentially messy; unlike with AMD's CLGI/STGI, only MSRs and other 
things that Intel thought can be restored atomically with the VM exit.

Paolo


  reply	other threads:[~2021-05-04 21:12 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-26 23:09 [PATCH 0/4] x86: Don't invoke asm_exc_nmi() on the kernel stack Lai Jiangshan
2021-04-26 23:09 ` [PATCH 1/4] x86/xen/entry: Rename xenpv_exc_nmi to noist_exc_nmi Lai Jiangshan
2021-04-28 21:27   ` Steven Rostedt
2021-04-30  7:15     ` Paolo Bonzini
2021-04-30 12:05       ` Steven Rostedt
2021-05-03 19:05   ` Thomas Gleixner
2021-05-03 19:41     ` Thomas Gleixner
2021-05-10  7:59   ` Juergen Gross
2021-04-26 23:09 ` [PATCH 2/4] x86/entry: Use asm_noist_exc_nmi() for NMI in early booting stage Lai Jiangshan
2021-04-28 21:30   ` Steven Rostedt
2021-05-03 20:13   ` Thomas Gleixner
2021-05-03 20:24     ` Thomas Gleixner
2021-05-03 21:45       ` Thomas Gleixner
2021-05-04 12:43         ` Thomas Gleixner
2021-05-04 19:50           ` [PATCH] KVM/VMX: Invoke NMI non-IST entry instead of IST entry Thomas Gleixner
2021-05-04 21:05             ` Maxim Levitsky
2021-05-04 21:12               ` Paolo Bonzini [this message]
2021-05-04 21:21                 ` Sean Christopherson
2021-05-04 21:23                   ` Andy Lutomirski
2021-05-04 21:25                     ` Paolo Bonzini
2021-05-04 21:51                       ` Sean Christopherson
2021-05-04 21:56                         ` Paolo Bonzini
2021-05-05  0:00                           ` Thomas Gleixner
2021-05-05 15:44                             ` Lai Jiangshan
2021-05-05  1:07                     ` Lai Jiangshan
2021-05-05  1:11                       ` Andy Lutomirski
2021-05-06 12:14             ` [tip: x86/urgent] " tip-bot2 for Lai Jiangshan
2021-04-26 23:09 ` [PATCH 3/4] " Lai Jiangshan
2021-04-30  2:46   ` Lai Jiangshan
2021-05-03 19:37   ` Thomas Gleixner
2021-05-03 20:02   ` Thomas Gleixner
2021-05-04  8:10     ` Paolo Bonzini
2021-04-26 23:09 ` [PATCH 4/4] KVM/VMX: Fold handle_interrupt_nmi_irqoff() into its solo caller Lai Jiangshan
2021-04-30  9:03   ` Thomas Gleixner
2021-04-30  9:06     ` Paolo Bonzini
2021-04-30 23:28       ` Thomas Gleixner
2021-04-30  7:14 ` [PATCH 0/4] x86: Don't invoke asm_exc_nmi() on the kernel stack Paolo Bonzini
2021-05-03 14:36   ` Thomas Gleixner

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