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SubjectRe: [RFC PATCH v5 021/104] KVM: x86: Introduce hooks to free VM callback prezap and vm_free
On Thu, Mar 31, 2022 at 04:02:24PM +1300,
Kai Huang <kai.huang@intel.com> wrote:

> On Fri, 2022-03-04 at 11:48 -0800, isaku.yamahata@intel.com wrote:
> > From: Kai Huang <kai.huang@intel.com>
> >
> > Before tearing down private page tables, TDX requires some resources of the
> > guest TD to be destroyed (i.e. keyID must have been reclaimed, etc). Add
> > prezap callback before tearing down private page tables for it.
> >
> > TDX needs to free some resources after other resources (i.e. vcpu related
> > resources). Add vm_free callback at the end of kvm_arch_destroy_vm().
> >
> > Signed-off-by: Kai Huang <kai.huang@intel.com>
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> > ---
> > arch/x86/include/asm/kvm-x86-ops.h | 2 ++
> > arch/x86/include/asm/kvm_host.h | 2 ++
> > arch/x86/kvm/x86.c | 8 ++++++++
> > 3 files changed, 12 insertions(+)
> >
> > diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
> > index 8125d43d3566..ef48dcc98cfc 100644
> > --- a/arch/x86/include/asm/kvm-x86-ops.h
> > +++ b/arch/x86/include/asm/kvm-x86-ops.h
> > @@ -20,7 +20,9 @@ KVM_X86_OP(has_emulated_msr)
> > KVM_X86_OP(vcpu_after_set_cpuid)
> > KVM_X86_OP(is_vm_type_supported)
> > KVM_X86_OP(vm_init)
> > +KVM_X86_OP_NULL(mmu_prezap)
> > KVM_X86_OP_NULL(vm_destroy)
> > +KVM_X86_OP_NULL(vm_free)
> > KVM_X86_OP(vcpu_create)
> > KVM_X86_OP(vcpu_free)
> > KVM_X86_OP(vcpu_reset)
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index 8de357a9ad30..5ff7a0fba311 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -1326,7 +1326,9 @@ struct kvm_x86_ops {
> > bool (*is_vm_type_supported)(unsigned long vm_type);
> > unsigned int vm_size;
> > int (*vm_init)(struct kvm *kvm);
> > + void (*mmu_prezap)(struct kvm *kvm);
> > void (*vm_destroy)(struct kvm *kvm);
> > + void (*vm_free)(struct kvm *kvm);
> >
> > /* Create, but do not attach this VCPU */
> > int (*vcpu_create)(struct kvm_vcpu *vcpu);
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index f6438750d190..a48f5c69fadb 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -11779,6 +11779,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
> > kvm_page_track_cleanup(kvm);
> > kvm_xen_destroy_vm(kvm);
> > kvm_hv_destroy_vm(kvm);
> > + static_call_cond(kvm_x86_vm_free)(kvm);
> > }
> >
> > static void memslot_rmap_free(struct kvm_memory_slot *slot)
> > @@ -12036,6 +12037,13 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
> >
> > void kvm_arch_flush_shadow_all(struct kvm *kvm)
> > {
> > + /*
> > + * kvm_mmu_zap_all() zaps both private and shared page tables. Before
> > + * tearing down private page tables, TDX requires some TD resources to
> > + * be destroyed (i.e. keyID must have been reclaimed, etc). Invoke
> > + * kvm_x86_mmu_prezap() for this.
> > + */
> > + static_call_cond(kvm_x86_mmu_prezap)(kvm);
> > kvm_mmu_zap_all(kvm);
> > }
> >
>
> The two callbacks are introduced here but they are actually implemented in 2
> patches later (patch 24 KVM: TDX: create/destroy VM structure). Why not just
> squash this patch to patch 24? Or at least you can put this patch right before
> patch 24.

Ok. I'll squash this patch into it.
--
Isaku Yamahata <isaku.yamahata@gmail.com>

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