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Tsirkin" , Peter Maydell , qemu-block@nongnu.org, Stefan Hajnoczi , Kevin Wolf , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Subject: [PATCH 25/31] hw/ppc/spapr_tpm_proxy: skip automatic zero-init of large arrays Date: Tue, 10 Jun 2025 13:37:03 +0100 Message-ID: <20250610123709.835102-26-berrange@redhat.com> In-Reply-To: <20250610123709.835102-1-berrange@redhat.com> References: <20250610123709.835102-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org The 'tpm_execute' method has a pair of 4k arrays used for copying data between guest and host. Skip the automatic zero-init of these arrays to eliminate the performance overhead in the I/O hot path. The two arrays will be fully initialized when reading data from guest memory or reading data from the proxy FD. Signed-off-by: Daniel P. Berrangé --- hw/ppc/spapr_tpm_proxy.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/hw/ppc/spapr_tpm_proxy.c b/hw/ppc/spapr_tpm_proxy.c index 862eeaa50a..1297b3ad56 100644 --- a/hw/ppc/spapr_tpm_proxy.c +++ b/hw/ppc/spapr_tpm_proxy.c @@ -41,8 +41,8 @@ static ssize_t tpm_execute(SpaprTpmProxy *tpm_proxy, target_ulong *args) target_ulong data_in_size = args[2]; uint64_t data_out = ppc64_phys_to_real(args[3]); target_ulong data_out_size = args[4]; - uint8_t buf_in[TPM_SPAPR_BUFSIZE]; - uint8_t buf_out[TPM_SPAPR_BUFSIZE]; + QEMU_UNINITIALIZED uint8_t buf_in[TPM_SPAPR_BUFSIZE]; + QEMU_UNINITIALIZED uint8_t buf_out[TPM_SPAPR_BUFSIZE]; ssize_t ret; trace_spapr_tpm_execute(data_in, data_in_size, data_out, data_out_size); -- 2.49.0