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References: <20240530210714.364118-1-rick.p.edgecombe@intel.com> <20240530210714.364118-2-rick.p.edgecombe@intel.com>
In-Reply-To: <20240530210714.364118-2-rick.p.edgecombe@intel.com>
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 6 Jun 2024 17:55:21 +0200
Message-ID: <CABgObfZ8qOJtui9ozU4sd-hnjNM_33qwA-jcJEeDc=RY5EoqfA@mail.gmail.com>
Subject: Re: [PATCH v2 01/15] KVM: Add member to struct kvm_gfn_range for
 target alias
To: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: seanjc@google.com, kvm@vger.kernel.org, kai.huang@intel.com, 
	dmatlack@google.com, erdemaktas@google.com, isaku.yamahata@gmail.com, 
	linux-kernel@vger.kernel.org, sagis@google.com, yan.y.zhao@intel.com, 
	Isaku Yamahata <isaku.yamahata@intel.com>
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On Thu, May 30, 2024 at 11:07=E2=80=AFPM Rick Edgecombe
<rick.p.edgecombe@intel.com> wrote:
> +       /* Unmmap the old attribute page. */

Unmap

> +       if (range->arg.attributes & KVM_MEMORY_ATTRIBUTE_PRIVATE)
> +               range->process =3D KVM_PROCESS_SHARED;
> +       else
> +               range->process =3D KVM_PROCESS_PRIVATE;
> +
>         return kvm_unmap_gfn_range(kvm, range);
>  }
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index c3c922bf077f..f92c8b605b03 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -260,11 +260,19 @@ union kvm_mmu_notifier_arg {
>         unsigned long attributes;
>  };
>
> +enum kvm_process {
> +       BUGGY_KVM_INVALIDATION          =3D 0,
> +       KVM_PROCESS_SHARED              =3D BIT(0),
> +       KVM_PROCESS_PRIVATE             =3D BIT(1),
> +       KVM_PROCESS_PRIVATE_AND_SHARED  =3D KVM_PROCESS_SHARED | KVM_PROC=
ESS_PRIVATE,
> +};

Only KVM_PROCESS_SHARED and KVM_PROCESS_PRIVATE are needed.

> +       /*
> +        * If/when KVM supports more attributes beyond private .vs shared=
, this
> +        * _could_ set exclude_{private,shared} appropriately if the enti=
re target

this could mask away KVM_PROCESS_{SHARED,PRIVATE} if the entire target...

Paolo

> +        * range already has the desired private vs. shared state (it's u=
nclear
> +        * if that is a net win).  For now, KVM reaches this point if and=
 only
> +        * if the private flag is being toggled, i.e. all mappings are in=
 play.
> +        */
> +
>         for (i =3D 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) {
>                 slots =3D __kvm_memslots(kvm, i);
>
> @@ -2506,6 +2519,7 @@ static int kvm_vm_set_mem_attributes(struct kvm *kv=
m, gfn_t start, gfn_t end,
>         struct kvm_mmu_notifier_range pre_set_range =3D {
>                 .start =3D start,
>                 .end =3D end,
> +               .arg.attributes =3D attributes,
>                 .handler =3D kvm_pre_set_memory_attributes,
>                 .on_lock =3D kvm_mmu_invalidate_begin,
>                 .flush_on_ret =3D true,
> --
> 2.34.1
>