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From:   Peter Gonda <pgonda@google.com>
Date:   Tue, 16 Nov 2021 11:39:25 -0700
Message-ID: <CAMkAt6o=G4U8iUkLxquT9E2JsyxVASOhNZcA9s7JFnrVPf_hfA@mail.gmail.com>
Subject: Re: [PATCH Part2 v5 00/45] Add AMD Secure Nested Paging (SEV-SNP)
 Hypervisor Support
To:     Sean Christopherson <seanjc@google.com>
Cc:     Joerg Roedel <jroedel@suse.de>, Andy Lutomirski <luto@kernel.org>,
        Marc Orr <marcorr@google.com>,
        "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
        Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@intel.com>,
        Brijesh Singh <brijesh.singh@amd.com>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        kvm list <kvm@vger.kernel.org>, linux-coco@lists.linux.dev,
        linux-mm@kvack.org,
        Linux Crypto Mailing List <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>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Sergio Lopez <slp@redhat.com>,
        "Peter Zijlstra (Intel)" <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 <tony.luck@intel.com>,
        Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>,
        Quentin Perret <qperret@google.com>
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On Tue, Nov 16, 2021 at 11:26 AM Sean Christopherson <seanjc@google.com> wrote:
>
> On Tue, Nov 16, 2021, Joerg Roedel wrote:
> > But as Marc already pointed out, the kernel needs a plan B when an RMP
> > happens anyway due to some bug.
>
> I don't see why unexpected RMP #PF is a special snowflake that needs a different
> plan than literally every other type of unexpected #PF in the kernel.

When I started this thread I was not trying to say we *need* to do
something different for RMP faults, but that we *could* improve host
reliability by doing something. Since it is possible to special case
an RMP fault and prevent a panic I thought it was with discussing.