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From: Sean Christopherson <seanjc@google.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Jane Malalane <jane.malalane@citrix.com>,
	LKML <linux-kernel@vger.kernel.org>,
	x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Pu Wen <puwen@hygon.cn>, Paolo Bonzini <pbonzini@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Yazen Ghannam <Yazen.Ghannam@amd.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Huang Rui <ray.huang@amd.com>, Andy Lutomirski <luto@kernel.org>,
	Kim Phillips <kim.phillips@amd.com>,
	stable@vger.kernel.org
Subject: Re: [PATCH v2] x86/cpu: Fix migration safety with X86_BUG_NULL_SEL
Date: Mon, 18 Oct 2021 20:05:10 +0000	[thread overview]
Message-ID: <YW3TdmEe/mx/5aOO@google.com> (raw)
In-Reply-To: <YW3M40tOILjI3DiD@zn.tnic>

On Mon, Oct 18, 2021, Borislav Petkov wrote:
> On Mon, Oct 18, 2021 at 07:29:41PM +0000, Sean Christopherson wrote:
> > I agree.  If the argument for this patch is that the kernel can be migrated to
> > older hardware, then it stands to reason that the kernel could also be migrated
> > to a different CPU vendor entirely.  E.g. start on Intel, migrate to Zen1, kaboom.
> 
> Migration across vendors? Really, that works?
> 
> I'll believe it only when I see it with my own eyes.

There are plenty of caveats, but it is feasible.  KVM even has a few patches that
came about specifically to support cross-vendor migration, e.g. commit adc2a23734ac
("KVM: nSVM: improve SYSENTER emulation on AMD").

  reply	other threads:[~2021-10-18 20:05 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-13 14:22 [PATCH v2] x86/cpu: Fix migration safety with X86_BUG_NULL_SEL Jane Malalane
2021-10-13 16:46 ` Greg KH
2021-10-18 18:17 ` Borislav Petkov
2021-10-18 19:10   ` H. Peter Anvin
2021-10-18 19:31     ` Borislav Petkov
2021-10-18 19:29   ` Sean Christopherson
2021-10-18 19:37     ` Borislav Petkov
2021-10-18 20:05       ` Sean Christopherson [this message]
2021-10-18 20:18         ` Andrew Cooper
2021-10-18 20:06   ` Andrew Cooper
2021-10-18 21:46     ` Borislav Petkov

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