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b=PeIQXPlfSANzXaigOELE825mnG9viAM/0D9dUAQ04X4qTtDSyUfhLiSWnr8O5aiGwqMaTW DOluFoKNVZDVF5EZgb57c5ddd9yCc+jMPInDs9BFo2Av9QdNmHiOlS2gmVpj7L0H48XWRZ IRTb78pabIsM4ZywZv4gbNOMcCWtuaM= X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 64C7CA008B X-Stat-Signature: rtq9xirc3chqzd5rcqnef5913ne5n8y8 Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=amd.com header.s=selector1 header.b=cm9RzlPz; dmarc=pass (policy=quarantine) header.from=amd.com; spf=pass (imf15.hostedemail.com: domain of Pankaj.Gupta@amd.com designates 40.107.92.71 as permitted sender) smtp.mailfrom=Pankaj.Gupta@amd.com; arc=pass ("microsoft.com:s=arcselector9901:i=1") X-HE-Tag: 1658439382-873132 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: >>>>> * The current patch should just work, but prefer to have pre-boot guest >>>>> payload/firmware population into private memory for performance. >>>> >>>> Not just performance in the case of SEV, it's needed there because firmware >>>> only supports in-place encryption of guest memory, there's no mechanism to >>>> provide a separate buffer to load into guest memory at pre-boot time. I >>>> think you're aware of this but wanted to point that out just in case. >>> >>> I view it as a performance problem because nothing stops KVM from copying from >>> userspace into the private fd during the SEV ioctl(). What's missing is the >>> ability for userspace to directly initialze the private fd, which may or may not >>> avoid an extra memcpy() depending on how clever userspace is. >> Can you please elaborate more what you see as a performance problem? And >> possible ways to solve it? > > Oh, I'm not saying there actually _is_ a performance problem. What I'm saying is > that in-place encryption is not a functional requirement, which means it's purely > an optimization, and thus we should other bother supporting in-place encryption > _if_ it would solve a performane bottleneck. Understood. Thank you! Best regards, Pankaj