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Re: [PATCH] x86/cpuid: Introduce dom0-cpuid command line option
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>
- Date: Wed, 15 Dec 2021 05:51:06 -0500
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- Cc: Jan Beulich <JBeulich@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>
- Delivery-date: Wed, 15 Dec 2021 10:52:00 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 12/14/21 4:16 PM, Andrew Cooper wrote:
Specifically, this lets the user opt in to non-default for dom0.
Split features[] out of parse_xen_cpuid(), giving it a lightly more
appropraite name, so it can be shared with parse_xen_cpuid().
Collect all dom0 settings together in dom0_{en,dis}able_feat[], and apply it
to dom0's policy when other tweaks are being made.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Daniel Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
RFC, because I think we've got a preexisting error with late hwdom here. We
really should not be cobbering a late hwdom's settings (which were provided in
the usual way by the toolstack in dom0).
Furthermore, the distinction gets more murky in a hyperlaunch future where
multiple domains may be constructed by Xen, and there is reason to expect that
a full toolstack-like configuration is made available for them.
For hyperlaunch, perhaps Christohper and I should revisit the DTB to add
a cpuid field/mask where CPU features can be masked out.
One option might be to remove the special case from init_domain_cpuid_policy()
and instead make a call into the cpuid code from create_dom0(). It would have
to be placed between domain_create() and alloc_dom0_vcpu0() for dynamic sizing
of the FPU block to work. Thoughts?
v/r,
dps
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