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Date:   Mon, 29 Jan 2018 23:12:58 -0200
From:   Eduardo Habkost <ehabkost@redhat.com>
To:     Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc:     David Woodhouse <dwmw2@infradead.org>,
        Arjan van de Ven <arjan@linux.intel.com>,
        KarimAllah Ahmed <karahmed@amazon.de>,
        linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Andy Lutomirski <luto@kernel.org>,
        Ashok Raj <ashok.raj@intel.com>,
        Asit Mallick <asit.k.mallick@intel.com>,
        Borislav Petkov <bp@suse.de>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "H . Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>,
        Joerg Roedel <joro@8bytes.org>,
        Jun Nakajima <jun.nakajima@intel.com>,
        Laura Abbott <labbott@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Tom Lendacky <thomas.lendacky@amd.com>, kvm@vger.kernel.org,
        x86@kernel.org, "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [RFC,05/10] x86/speculation: Add basic IBRS support
 infrastructure
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On Mon, Jan 29, 2018 at 05:10:11PM -0500, Konrad Rzeszutek Wilk wrote:
[...]
> The migration code could be 'tickled' (when arrived at the destination)
> to recheck the CPUID and do the alternative logic to turn the
> proper bits on.
> 
> And this tickling could be as simple as an ACPI DSDT/AML code
> specific to KVM PnP devices (say the CPUs?) to tell the guest to
> resample its environment?

This would be nice to have for other CPU features, but if I
understood a previous message from Andi on this thread correctly,
it wouldn't be useful for the Spectre mitigations.

-- 
Eduardo