From: "Daniel P. Berrangé" <berrange@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Yang Zhong <yang.zhong@intel.com>,
eduardo@habkost.net, qemu-devel@nongnu.org, pbonzini@redhat.com
Subject: Re: [PATCH] sgx: Move sgx object from /machine/unattached to /machine
Date: Wed, 12 Jan 2022 10:24:33 +0000 [thread overview]
Message-ID: <Yd6sYaHLtCgMLMKS@redhat.com> (raw)
In-Reply-To: <CAFEAcA-K2uVc2NpfHBQokBZBRSeTGm0dnr7UCLE+sN+Ro-Lj8w@mail.gmail.com>
On Wed, Jan 12, 2022 at 10:16:33AM +0000, Peter Maydell wrote:
> 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.
So how do CPUs and other devices end up being under /unattached/ ?
Can we ensure that *all* QEMU devices have a well defined attachment
point ?
Regards,
Daniel
--
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next prev parent reply other threads:[~2022-01-12 10:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-12 16:55 [PATCH] sgx: Move sgx object from /machine/unattached to /machine Yang Zhong
2022-01-12 10:11 ` Daniel P. Berrangé
2022-01-12 10:16 ` Peter Maydell
2022-01-12 10:24 ` Daniel P. Berrangé [this message]
2022-01-13 7:05 ` Yang Zhong
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