| Message ID | 1459370289-15994-1-git-send-email-yuzhao@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 30/03/2016 22:38, Yu Zhao wrote: > In absence of shadow dirty mask, there is no need to set page dirty > if page has never been writable. This is a tiny optimization but > good to have for people who care much about dirty page tracking. > > Signed-off-by: Yu Zhao <yuzhao@google.com> > --- > arch/x86/kvm/mmu.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 70e95d0..1ff4dbb 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -557,8 +557,15 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte) > !is_writable_pte(new_spte)) > ret = true; > > - if (!shadow_accessed_mask) > + if (!shadow_accessed_mask) { > + /* > + * We don't set page dirty when dropping non-writable spte. > + * So do it now if the new spte is becoming non-writable. > + */ > + if (ret) > + kvm_set_pfn_dirty(spte_to_pfn(old_spte)); > return ret; > + } > > /* > * Flush TLB when accessed/dirty bits are changed in the page tables, > @@ -605,7 +612,8 @@ static int mmu_spte_clear_track_bits(u64 *sptep) > > if (!shadow_accessed_mask || old_spte & shadow_accessed_mask) > kvm_set_pfn_accessed(pfn); > - if (!shadow_dirty_mask || (old_spte & shadow_dirty_mask)) > + if (old_spte & (shadow_dirty_mask ? shadow_dirty_mask : > + PT_WRITABLE_MASK)) > kvm_set_pfn_dirty(pfn); > return 1; > } > Looks good, thanks! Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 70e95d0..1ff4dbb 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -557,8 +557,15 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte) !is_writable_pte(new_spte)) ret = true; - if (!shadow_accessed_mask) + if (!shadow_accessed_mask) { + /* + * We don't set page dirty when dropping non-writable spte. + * So do it now if the new spte is becoming non-writable. + */ + if (ret) + kvm_set_pfn_dirty(spte_to_pfn(old_spte)); return ret; + } /* * Flush TLB when accessed/dirty bits are changed in the page tables, @@ -605,7 +612,8 @@ static int mmu_spte_clear_track_bits(u64 *sptep) if (!shadow_accessed_mask || old_spte & shadow_accessed_mask) kvm_set_pfn_accessed(pfn); - if (!shadow_dirty_mask || (old_spte & shadow_dirty_mask)) + if (old_spte & (shadow_dirty_mask ? shadow_dirty_mask : + PT_WRITABLE_MASK)) kvm_set_pfn_dirty(pfn); return 1; }
In absence of shadow dirty mask, there is no need to set page dirty if page has never been writable. This is a tiny optimization but good to have for people who care much about dirty page tracking. Signed-off-by: Yu Zhao <yuzhao@google.com> --- arch/x86/kvm/mmu.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)