Messages in this thread | | | From | Ben Gardon <> | Date | Mon, 6 Feb 2023 14:09:42 -0800 | Subject | Re: [Patch v2 1/5] KVM: x86/mmu: Make separate function to check for SPTEs atomic write conditions |
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On Fri, Feb 3, 2023 at 11:28 AM Vipin Sharma <vipinsh@google.com> wrote: > > Move condition checks in kvm_tdp_mmu_write_spte() for writing spte > atomically in a separate function. > > New function will be used in future commits to clear bits in SPTE. > > Signed-off-by: Vipin Sharma <vipinsh@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
> --- > arch/x86/kvm/mmu/tdp_iter.h | 16 +++++++++++----- > 1 file changed, 11 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/mmu/tdp_iter.h b/arch/x86/kvm/mmu/tdp_iter.h > index f0af385c56e0..30a52e5e68de 100644 > --- a/arch/x86/kvm/mmu/tdp_iter.h > +++ b/arch/x86/kvm/mmu/tdp_iter.h > @@ -29,11 +29,10 @@ static inline void __kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 new_spte) > WRITE_ONCE(*rcu_dereference(sptep), new_spte); > } > > -static inline u64 kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 old_spte, > - u64 new_spte, int level) > +static inline bool kvm_tdp_mmu_spte_has_volatile_bits(u64 old_spte, int level) > { > /* > - * Atomically write the SPTE if it is a shadow-present, leaf SPTE with > + * Atomically write SPTEs if it is a shadow-present, leaf SPTE with
Nit: SPTEs must be modified atomically if they are shadow-present, leaf SPTEs with
> * volatile bits, i.e. has bits that can be set outside of mmu_lock. > * The Writable bit can be set by KVM's fast page fault handler, and > * Accessed and Dirty bits can be set by the CPU. > @@ -44,8 +43,15 @@ static inline u64 kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 old_spte, > * logic needs to be reassessed if KVM were to use non-leaf Accessed > * bits, e.g. to skip stepping down into child SPTEs when aging SPTEs. > */ > - if (is_shadow_present_pte(old_spte) && is_last_spte(old_spte, level) && > - spte_has_volatile_bits(old_spte)) > + return is_shadow_present_pte(old_spte) && > + is_last_spte(old_spte, level) && > + spte_has_volatile_bits(old_spte); > +} > + > +static inline u64 kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 old_spte, > + u64 new_spte, int level) > +{ > + if (kvm_tdp_mmu_spte_has_volatile_bits(old_spte, level)) > return kvm_tdp_mmu_write_spte_atomic(sptep, new_spte); > > __kvm_tdp_mmu_write_spte(sptep, new_spte); > -- > 2.39.1.519.gcb327c4b5f-goog >
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