Messages in this thread | | | Date | Thu, 21 Jul 2022 22:05:16 +0200 | Subject | Re: [PATCH v5 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory | From | "Gupta, Pankaj" <> |
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Hi Sean, Chao,
While attempting to solve the pre-boot guest payload/firmware population into private memory for SEV SNP, retrieved this thread. Have question below:
>>> Requirements & Gaps >>> ------------------------------------- >>> - Confidential computing(CC): TDX/SEV/CCA >>> * Need support both explicit/implicit conversions. >>> * Need support only destructive conversion at runtime. >>> * 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?
Thanks, Pankaj
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