linux-kernel - Re: [PATCH] x86/sev: Make early_set_memory

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Date:   Fri, 15 Sep 2023 11:44:16 -0700
From:   Steve Rutherford <srutherford@...gle.com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H . Peter Anvin" <hpa@...or.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, David.Kaplan@....com,
        jacobhxu@...gle.com, patelsvishal@...gle.com, bhillier@...gle.com
Subject: Re: [PATCH] x86/sev: Make early_set_memory_decrypted() calls page aligned

I believe V3 of this fix was already merged into both x86 and Linus'
tree (I think as ac3f9c9f1b37edaa7d1a9b908bc79d843955a1a2, "x86/sev:
Make enc_dec_hypercall() accept a size instead of npages").


On Fri, Sep 15, 2023 at 4:59 AM Ingo Molnar <mingo@...nel.org> wrote:
>
>
> * Steve Rutherford <srutherford@...gle.com> wrote:
>
> > early_set_memory_decrypted() assumes its parameters are page aligned.
> > Non-page aligned calls result in additional pages being marked as
> > decrypted via the encryption status hypercall, which results in
> > consistent corruption of pages during live migration. Live
> > migration requires accurate encryption status information to avoid
> > migrating pages from the wrong perspective.
> >
> > Fixes: 4716276184ec ("X86/KVM: Decrypt shared per-cpu variables when SEV is active")
> > Signed-off-by: Steve Rutherford <srutherford@...gle.com>
> > ---
> >  arch/x86/kernel/kvm.c | 14 +++++++++++++-
> >  1 file changed, 13 insertions(+), 1 deletion(-)
>
> I suppose this fix is going through the KVM tree, or should we pick it up
> in the x86 tree?
>
> Thanks,
>
>         Ingo