linux-kernel - Re: [PATCH 0/2] KVM: x86: Propagate AMD-specific IBRS bits to guests

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Message-ID: <Y/5oBKi6vjZe83ac@zn.tnic>
Date:   Tue, 28 Feb 2023 21:45:56 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Takahiro Itazuri <itazur@...zon.com>
Cc:     dave.hansen@...ux.intel.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, mingo@...hat.com,
        pbonzini@...hat.com, seanjc@...gle.com, tglx@...utronix.de,
        x86@...nel.org, zulinx86@...il.com
Subject: Re: [PATCH 0/2] KVM: x86: Propagate AMD-specific IBRS bits to guests

On Tue, Feb 28, 2023 at 07:41:53PM +0000, Takahiro Itazuri wrote:
> It is true that the kernel does not use those bits at all, but any
> codes could be run inside guests.

So you mean we should stick *all* CPUID leafs in there just because
anything can run in guests?

What is the hypervisor then for?

> One of examples is the following spectre/meltdown checker scipt used as
> de facto standard.

Really? Says who?

$ grep -r . /sys/devices/system/cpu/vulnerabilities/

gives you all you need to know.

And if something's missing, then I'm listening.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette