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Re: [PATCH] sgx: Move sgx object from /machine/unattached to /machine
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From: |
Peter Maydell |
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Subject: |
Re: [PATCH] sgx: Move sgx object from /machine/unattached to /machine |
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Date: |
Wed, 12 Jan 2022 10:16:33 +0000 |
On Wed, 12 Jan 2022 at 10:14, Daniel P. Berrangé <berrange@redhat.com> wrote:
>
> On Wed, Jan 12, 2022 at 11:55:17AM -0500, Yang Zhong wrote:
> > When Libvirt start, it get the vcpu's unavailable-features from
> > /machine/unattached/device[0] path by qom-get command, but in SGX
> > guest, since the sgx-epc virtual device is initialized before VCPU
> > creation(virtual sgx need set the virtual EPC info in the cpuid). This
> > /machine/unattached/device[0] is occupied by sgx-epc device, which
> > fail to get the unvailable-features from /machine/unattached/device[0].
>
> If libvirt decides to enable SGX in a VM, then surely it knows
> that it should just query /machine/unattached/device[1] to get
> the CPU features instead. Why do we need to do anything in QEMU ?
libvirt having to know it needs to look at /machine/unattached/device[n]
for anything is a bit fragile, really... it's effectively encoding
knowledge about what order things happen to get created inside QEMU.
-- PMM