linux-kernel - Re: [PATCH v6 5/5] x86/kvm: Avoid dynamic allocation of pvclock data when SEV is active

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Message-ID: <20180910155329.GB20286@zn.tnic>
Date:   Mon, 10 Sep 2018 17:53:29 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Tom Lendacky <thomas.lendacky@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: Re: [PATCH v6 5/5] x86/kvm: Avoid dynamic allocation of pvclock data
 when SEV is active

On Mon, Sep 10, 2018 at 08:15:38AM -0500, Brijesh Singh wrote:
> > Now, the real question from all this SNAFU is, why can't all those point
> > to a single struct pvclock_vsyscall_time_info and all CPUs read a single
> > thing? Why do they have to be per-CPU and thus waste so much memory?

You forgot to answer to the real question - why do we need those things
to be perCPU and why can't we use a single instance to share with *all*
CPUs?

Because if we can, then we're golden!

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--