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Message-ID: <CABgObfYvkT39Msd11uJMZMquOsvNKBa=Z548JQZGfOmCF=TPaA@mail.gmail.com>
Date: Tue, 7 May 2024 19:20:51 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Kai Huang <kai.huang@...el.com>, Xiaoyao Li <xiaoyao.li@...el.com>,
"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3] KVM: x86: Fix supported VM_TYPES caps
On Mon, Apr 29, 2024 at 5:56 PM Sean Christopherson <seanjc@...gle.com> wrote:
> > Perhaps we can make the kvm.ko as a dummy module which only keeps the module
> > parameters for backward compatibility?
>
> Keeping parameters in a dummy kvm.ko would largely defeat the purpose of linking
> everything into vendor modules, i.e. would make it possible for the parameters to
> hold a stale value.
We have the following read-write params:
parm: nx_huge_pages:bool
parm: nx_huge_pages_recovery_ratio:uint
parm: nx_huge_pages_recovery_period_ms:uint
parm: flush_on_reuse:bool
parm: ignore_msrs:bool
parm: report_ignored_msrs:bool
parm: min_timer_period_us:uint
parm: tsc_tolerance_ppm:uint
parm: lapic_timer_advance_ns:int
parm: force_emulation_prefix:int
parm: pi_inject_timer:bint
parm: eager_page_split:bool
parm: halt_poll_ns:uint
parm: halt_poll_ns_grow:uint
parm: halt_poll_ns_grow_start:uint
parm: halt_poll_ns_shrink:uint
Vendor modules do not muck with them (the only one that is exported is
report_ignored_msrs for which permanency is obviously harmless).
And the following read-only params:
parm: tdp_mmu:bool
parm: mmio_caching:bool
parm: kvmclock_periodic_sync:bool
parm: vector_hashing:bool
parm: enable_vmware_backdoor:bool
parm: enable_pmu:bool
parm: mitigate_smt_rsb:bool
The only really bad one is tdp_mmu, which can change depending on the
ept/npt parameters of kvm-intel/kvm-amd; everything else is okay to
have in a common module.
mitigate_smt_rsb could (should?) move to kvm-amd.ko if the modules
were unified with kvm.ko as a dummy one.
Paolo
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