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[82.30.61.225]) by smtp.gmail.com with ESMTPSA id t8sm17359470wmq.32.2021.11.15.07.33.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Nov 2021 07:33:05 -0800 (PST) Date: Mon, 15 Nov 2021 15:33:03 +0000 From: "Dr. David Alan Gilbert" To: Joerg Roedel Cc: Sean Christopherson , Borislav Petkov , Dave Hansen , Peter Gonda , Brijesh Singh , 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 , Ingo Molnar , Tom Lendacky , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , Dov Murik , Tobin Feldman-Fitzthum , Michael Roth , Vlastimil Babka , "Kirill A . Shutemov" , Andi Kleen , 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: References: <20210820155918.7518-1-brijesh.singh@amd.com> <061ccd49-3b9f-d603-bafd-61a067c3f6fa@intel.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.0.7 (2021-05-04) X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: CC1864002088 X-Stat-Signature: g5s6hatyu55a7fzi7ws83u6fwcmqwsqa Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=iSq5dZ11; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=MV7tNKeW; spf=none (imf18.hostedemail.com: domain of dgilbert@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=dgilbert@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-HE-Tag: 1636990396-43785 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: * Joerg Roedel (jroedel@suse.de) wrote: > On Mon, Nov 15, 2021 at 12:30:59PM +0000, Dr. David Alan Gilbert wrote: > > Still; I wonder if it's best to kill the guest - maybe it's best for > > the host to kill the guest and leave behind diagnostics of what > > happened; for someone debugging the crash, it's going to be less useful > > to know that page X was wrongly accessed (which is what the guest would > > see), and more useful to know that it was the kernel's vhost-... driver > > that accessed it. > > I is best to let the guest #VC on the page when this happens. If it > happened because of a guest bug all necessary debugging data is in the > guest and only the guest owner can obtain it. > > Then the guest owner can do a kdump on this unexpected #VC and collect > the data to debug the issue. With just killing the guest from the host > side this data would be lost. How would you debug an unexpected access by the host kernel using a guests kdump? Dave > Regards, > > Joerg > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK