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([2001:b07:6468:f312:ec9b:111a:97e3:4baf]) by smtp.gmail.com with ESMTPSA id j26sm4239894wrc.79.2020.09.25.13.56.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Sep 2020 13:56:11 -0700 (PDT) Subject: Re: SEV guest debugging support for Qemu To: Ashish Kalra References: <20200922201124.GA6606@ashkalra_ubuntu_server> <5a58509c-5838-f0aa-d9ab-4f85ca0ac35f@redhat.com> <20200925204607.GA10964@ashkalra_ubuntu_server> From: Paolo Bonzini Message-ID: Date: Fri, 25 Sep 2020 22:56:10 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200925204607.GA10964@ashkalra_ubuntu_server> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/25 01:07:33 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.199, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.238, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: thomas.lendacky@amd.com, jon.grimm@amd.com, brijesh.singh@amd.com, dgilbert@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 25/09/20 22:46, Ashish Kalra wrote: > I was also considering abstracting this vendor/SEV specific debug > interface via the CPUClass object, the CPUClass object aleady has cpu > specific methods for doing things like guest VA to GPA translations like the > get_phys_page_attrs_debug() method and it will be a simple and clean > approach to override this method with a SEV specific > get_phys_page_attrs_debug() if SEV guest is active and SEV debug policy > is allowed. [...] > > I can probably add new interfaces/methods to this CPUClass object for > guest memory read/writes for debugging purpose and then invoke the same > from the generic cpu_memory_rw_debug() interface. > > Let me know your thougts on abstracting this debug interface via the > CPUClass object ? > > Or the other option is to introduce the new MemoryDebugOps you described > above and additionally apply SEV/SEV-ES considerations in CPUClass > methods such as gdb_read_register, gdb_write_register, etc. Yes, this makes the most sense, however you're right that you don't need translate in MemoryDebugOps. I don't think read/write should be moved to CPUClass, however, since you can use a MemTxAttr to tell the read/write MemoryDebugOps whether the page is encrypted or not. Paolo