Date:   Mon, 15 Nov 2021 16:32:38 +0000
From:   "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To:     Joerg Roedel <jroedel@suse.de>
Cc:     Sean Christopherson <seanjc@google.com>,
        Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@intel.com>,
        Peter Gonda <pgonda@google.com>,
        Brijesh Singh <brijesh.singh@amd.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        linux-coco@lists.linux.dev, linux-mm@kvack.org,
        linux-crypto@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        Tom Lendacky <Thomas.Lendacky@amd.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Ard Biesheuvel <ardb@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Sergio Lopez <slp@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        David Rientjes <rientjes@google.com>,
        Dov Murik <dovmurik@linux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@ibm.com>,
        Michael Roth <michael.roth@amd.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        "Kirill A . Shutemov" <kirill@shutemov.name>,
        Andi Kleen <ak@linux.intel.com>, tony.luck@intel.com,
        marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com
Subject: Re: [PATCH Part2 v5 00/45] Add AMD Secure Nested Paging (SEV-SNP)
 Hypervisor Support
Message-ID: <YZKLpiinvKcE896u@work-vm>
References: <20210820155918.7518-1-brijesh.singh@amd.com>
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* Joerg Roedel (jroedel@suse.de) wrote:
> On Mon, Nov 15, 2021 at 03:33:03PM +0000, Dr. David Alan Gilbert wrote:
> > How would you debug an unexpected access by the host kernel using a
> > guests kdump?
> 
> The host needs to log the access in some way (trace-event, pr_err) with
> relevant information.

Yeh OK that makes sense if the host-owner could then enable some type of
debugging based on that event for the unfortunate guest owner.

> And with the guest-side kdump you can rule out that it was a guest bug
> which triggered the access. And you learn what the guest was trying to
> do when it triggered the access. This also helps finding the issue on
> the host side (if it is a host-side issue).
> 
> (Guest and host owner need to work together for debugging, of course).

Yeh.

Dave

> Regards,
> 
> -- 
> J?rg R?del
> jroedel@suse.de
> 
> SUSE Software Solutions Germany GmbH
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-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK