On Thu, May 27, 2021, Sean Christopherson wrote:
> On Fri, Apr 23, 2021, Sean Christopherson wrote:
> > Remove the @reset_roots param from kvm_init_mmu(), the one user,
> > kvm_mmu_reset_context() has already unloaded the MMU and thus freed and
> > invalidated all roots. This also happens to be why the reset_roots=true
> > paths doesn't leak roots; they're already invalid.
> >
> > No functional change intended.
> >
> > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> > ---
> > arch/x86/kvm/mmu.h | 2 +-
> > arch/x86/kvm/mmu/mmu.c | 13 ++-----------
> > arch/x86/kvm/svm/nested.c | 2 +-
> > arch/x86/kvm/vmx/nested.c | 2 +-
> > 4 files changed, 5 insertions(+), 14 deletions(-)
> >
> > diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
> > index 88d0ed5225a4..63b49725fb24 100644
> > --- a/arch/x86/kvm/mmu.h
> > +++ b/arch/x86/kvm/mmu.h
> > @@ -65,7 +65,7 @@ void kvm_mmu_set_ept_masks(bool has_ad_bits, bool has_exec_only);
> > void
> > reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context);
> >
> > -void kvm_init_mmu(struct kvm_vcpu *vcpu, bool reset_roots);
> > +void kvm_init_mmu(struct kvm_vcpu *vcpu);
> > void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, u32 cr0, u32 cr4, u32 efer,
> > gpa_t nested_cr3);
> > void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
> > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> > index 930ac8a7e7c9..ff3e200b32dd 100644
> > --- a/arch/x86/kvm/mmu/mmu.c
> > +++ b/arch/x86/kvm/mmu/mmu.c
> > @@ -4793,17 +4793,8 @@ static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu)
> > update_last_nonleaf_level(vcpu, g_context);
> > }
> >
> > -void kvm_init_mmu(struct kvm_vcpu *vcpu, bool reset_roots)
> > +void kvm_init_mmu(struct kvm_vcpu *vcpu)
> > {
> > - if (reset_roots) {
> > - uint i;
> > -
> > - vcpu->arch.mmu->root_hpa = INVALID_PAGE;
> > -
> > - for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
> > - vcpu->arch.mmu->prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID;
>
> Egad! This is wrong. mmu->root_hpa is guaranteed to be INVALID_PAGE, but the
> prev_roots are not! I'll drop this patch and do cleanup of this code in a
> separate series.
*sigh* Jumped the gun, I was right the first time. kvm_mmu_free_roots() does
invalidate prev_roots[*] via mmu_free_root_page(). I still think I'll drop this
patch from this series, I don't think there's anything in this series that is
needed to purge @reset_roots.
for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i))
mmu_free_root_page(kvm, &mmu->prev_roots[i].hpa, <-- tricky little devil
&invalid_list);
>
> > - }
> > -
> > if (mmu_is_nested(vcpu))
> > init_kvm_nested_mmu(vcpu);
> > else if (tdp_enabled)
