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Subject: Re: [PATCH 03/13] kvm: monolithic: fixup x86-32 build
To:     Andrea Arcangeli <aarcange@redhat.com>
Cc:     Jessica Yu <jeyu@kernel.org>, kvm@vger.kernel.org,
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        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
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        Matthias Maennich <maennich@google.com>
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From:   Paolo Bonzini <pbonzini@redhat.com>
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Date:   Fri, 8 Nov 2019 22:02:52 +0100
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On 08/11/19 21:01, Andrea Arcangeli wrote:
> On Fri, Nov 08, 2019 at 08:51:04PM +0100, Paolo Bonzini wrote:
>> I suppose we could use code patching mechanism to avoid the retpolines.
>>  Andrea, what do you think about that?  That would have the advantage
>> that we won't have to remove kvm_x86_ops. :)
> 
> page 17 covers pvops:
> 
> https://people.redhat.com/~aarcange/slides/2019-KVM-monolithic.pdf

You can patch call instructions directly using text_poke when
kvm_intel.ko or kvm_amd.ko, I'm not sure why that would be worse for TLB
or RAM usage.  The hard part is recording the location of the call sites
using some pushsection/popsection magic.

Paolo