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Tsirkin" , Marcel Apfelbaum , Cornelia Huck , =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , Marcelo Tosatti , Laszlo Ersek , Gerd Hoffmann , Eric Blake References: <20220317135913.2166202-1-xiaoyao.li@intel.com> <20220317135913.2166202-18-xiaoyao.li@intel.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= In-Reply-To: <20220317135913.2166202-18-xiaoyao.li@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Host-Lookup-Failed: Reverse DNS lookup failed for 2607:f8b0:4864:20::62d (failed) Received-SPF: pass client-ip=2607:f8b0:4864:20::62d; envelope-from=philippe.mathieu.daude@gmail.com; helo=mail-pl1-x62d.google.com X-Spam_score_int: -6 X-Spam_score: -0.7 X-Spam_bar: / X-Spam_report: (-0.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, NICE_REPLY_A=-0.001, PDS_HP_HELO_NORDNS=0.659, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: isaku.yamahata@intel.com, kvm@vger.kernel.org, Connor Kuehl , seanjc@google.com, qemu-devel@nongnu.org, erdemaktas@google.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi, On 17/3/22 14:58, Xiaoyao Li wrote: > TDX VM needs to boot with Trust Domain Virtual Firmware (TDVF). Unlike > that OVMF is mapped as rom device, TDVF needs to be mapped as private > memory. This is because TDX architecture doesn't provide read-only > capability for VMM, and it doesn't support instruction emulation due > to guest memory and registers are not accessible for VMM. > > On the other hand, OVMF can work as TDVF, which is usually configured > as pflash device in QEMU. To keep the same usage (QEMU parameter), > introduce ram_mode to pflash for TDVF. When it's creating a TDX VM, > ram_mode will be enabled automatically that map the firmware as RAM. > > Note, this implies two things: > 1. TDVF (OVMF) is not read-only (write-protected). > > 2. It doesn't support non-volatile UEFI variables as what pflash > supports that the change to non-volatile UEFI variables won't get > synced back to backend vars.fd file. > > Signed-off-by: Xiaoyao Li > --- > hw/block/pflash_cfi01.c | 25 ++++++++++++++++++------- > hw/i386/pc_sysfw.c | 14 +++++++++++--- > 2 files changed, 29 insertions(+), 10 deletions(-) If you don't need a pflash device, don't use it: simply map your nvram region as ram in your machine. No need to clutter the pflash model like that. NAcked-by: Philippe Mathieu-Daudé