linux-kernel - Re: [PATCH kernel v2 2/3] KVM: SEV: Enable data breakpoints in SEV-ES

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Message-ID: <Y7/u76mREet2IrtQ@zn.tnic>
Date:   Thu, 12 Jan 2023 12:28:47 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Alexey Kardashevskiy <aik@....com>
Cc:     Tom Lendacky <thomas.lendacky@....com>, kvm@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Venu Busireddy <venu.busireddy@...cle.com>,
        Tony Luck <tony.luck@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sean Christopherson <seanjc@...gle.com>,
        Sandipan Das <sandipan.das@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Michael Roth <michael.roth@....com>,
        Mario Limonciello <mario.limonciello@....com>,
        Jan Kara <jack@...e.cz>, Ingo Molnar <mingo@...hat.com>,
        Huang Rui <ray.huang@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH kernel v2 2/3] KVM: SEV: Enable data breakpoints in SEV-ES

On Thu, Jan 12, 2023 at 04:45:34PM +1100, Alexey Kardashevskiy wrote:
> Well, SEV-ES KVM (ES == Encrypted State) does not save/restore them for the
> guest (well, as I would expect) as the guest registers are not visible to
> host to save, they are intercepted and the VM does this GHCB dance with
> VMGEXIT(SVM_EXIT_WRITE_DR7).

But they're saved in the VMSA, as Table B-3 says.

> Well, the only place in APM is that "Table B-3. Swap Types and the AMD APM
> volume 2", and it is pretty brief, do I miss something?

I don't understand that question - please elaborate.

Thx.

-- 
Regards/Gruss,
    Boris.

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