| Message ID | 1244651005-18322-3-git-send-email-ieidus@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Izik Eidus wrote: > +static int vmx_dirty_bit_support(void) > +{ > + return false; > +} > + > Again, idiotic bug: this should be: return tdp_enable == false; ... -- 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
On Wed, Jun 10, 2009 at 07:23:25PM +0300, Izik Eidus wrote: > change the dirty page tracking to work with dirty bity instead of page fault. > right now the dirty page tracking work with the help of page faults, when we > want to track a page for being dirty, we write protect it and we mark it dirty > when we have write page fault, this code move into looking at the dirty bit > of the spte. > > Signed-off-by: Izik Eidus <ieidus@redhat.com> > --- > arch/ia64/kvm/kvm-ia64.c | 4 +++ > arch/powerpc/kvm/powerpc.c | 4 +++ > arch/s390/kvm/kvm-s390.c | 4 +++ > arch/x86/include/asm/kvm_host.h | 3 ++ > arch/x86/kvm/mmu.c | 42 ++++++++++++++++++++++++++++++++++++-- > arch/x86/kvm/svm.c | 7 ++++++ > arch/x86/kvm/vmx.c | 7 ++++++ > arch/x86/kvm/x86.c | 26 ++++++++++++++++++++--- > include/linux/kvm_host.h | 1 + > virt/kvm/kvm_main.c | 6 ++++- > 10 files changed, 96 insertions(+), 8 deletions(-) > > diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c > index 3199221..5914128 100644 > --- a/arch/ia64/kvm/kvm-ia64.c > +++ b/arch/ia64/kvm/kvm-ia64.c > @@ -1809,6 +1809,10 @@ void kvm_arch_exit(void) > kvm_vmm_info = NULL; > } > > +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) > +{ > +} > + > static int kvm_ia64_sync_dirty_log(struct kvm *kvm, > struct kvm_dirty_log *log) > { > diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c > index 2cf915e..6beb368 100644 > --- a/arch/powerpc/kvm/powerpc.c > +++ b/arch/powerpc/kvm/powerpc.c > @@ -418,6 +418,10 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) > return -ENOTSUPP; > } > #ifndef KVM_ARCH_HAVE_DIRTY_LOG > +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) > +{ > +} > + #endif in virt/kvm/main.c > index c7b0cc2..8a24149 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -527,6 +527,7 @@ struct kvm_x86_ops { > int (*set_tss_addr)(struct kvm *kvm, unsigned int addr); > int (*get_tdp_level)(void); > u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio); > + int (*dirty_bit_support)(void); > }; > > extern struct kvm_x86_ops *kvm_x86_ops; > @@ -796,4 +797,6 @@ int kvm_unmap_hva(struct kvm *kvm, unsigned long hva); > int kvm_age_hva(struct kvm *kvm, unsigned long hva); > int cpuid_maxphyaddr(struct kvm_vcpu *vcpu); > > +int is_dirty_and_clean_rmapp(struct kvm *kvm, unsigned long *rmapp); > + > #endif /* _ASM_X86_KVM_HOST_H */ > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 809cce0..500e0e2 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -140,6 +140,8 @@ module_param(oos_shadow, bool, 0644); > #define ACC_USER_MASK PT_USER_MASK > #define ACC_ALL (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK) > > +#define SPTE_DONT_DIRTY (1ULL << PT_FIRST_AVAIL_BITS_SHIFT) > + > #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level) > > struct kvm_rmap_desc { > @@ -629,6 +631,29 @@ static u64 *rmap_next(struct kvm *kvm, unsigned long *rmapp, u64 *spte) > return NULL; > } > > +int is_dirty_and_clean_rmapp(struct kvm *kvm, unsigned long *rmapp) > +{ > + u64 *spte; > + int dirty = 0; > + > + if (!shadow_dirty_mask) > + return 0; > + > + spte = rmap_next(kvm, rmapp, NULL); > + while (spte) { > + if (*spte & PT_DIRTY_MASK) { > + set_shadow_pte(spte, (*spte &= ~PT_DIRTY_MASK) | > + SPTE_DONT_DIRTY); > + dirty = 1; > + break; > + } > + spte = rmap_next(kvm, rmapp, spte); > + } > + > + return dirty; > +} > + > + > static int rmap_write_protect(struct kvm *kvm, u64 gfn) > { > unsigned long *rmapp; > @@ -1381,11 +1406,17 @@ static int mmu_zap_unsync_children(struct kvm *kvm, > static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp) > { > int ret; > + int i; > + > ++kvm->stat.mmu_shadow_zapped; > ret = mmu_zap_unsync_children(kvm, sp); > kvm_mmu_page_unlink_children(kvm, sp); > kvm_mmu_unlink_parents(kvm, sp); > kvm_flush_remote_tlbs(kvm); > + for (i = 0; i < PT64_ENT_PER_PAGE; ++i) { > + if (sp->spt[i] & PT_DIRTY_MASK) > + mark_page_dirty(kvm, sp->gfns[i]); > + } Also need to transfer dirty bit in other places probably. > if (!sp->role.invalid && !sp->role.direct) > unaccount_shadowed(kvm, sp->gfn); > if (sp->unsync) > @@ -1676,7 +1707,10 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, > * whether the guest actually used the pte (in order to detect > * demand paging). > */ > - spte = shadow_base_present_pte | shadow_dirty_mask; > + spte = shadow_base_present_pte; > + if (!(spte & SPTE_DONT_DIRTY)) > + spte |= shadow_dirty_mask; > + > if (!speculative) > spte |= shadow_accessed_mask; > if (!dirty) > @@ -1725,8 +1759,10 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, > } > } > > - if (pte_access & ACC_WRITE_MASK) > - mark_page_dirty(vcpu->kvm, gfn); > + if (!shadow_dirty_mask) { > + if (pte_access & ACC_WRITE_MASK) > + mark_page_dirty(vcpu->kvm, gfn); > + } You can avoid the mark_page_dirty if SPTE_DONT_DIRTY? (which is a good idea, gfn_to_memslot_unaliased and friends show up high in profiling). > set_pte: > set_shadow_pte(shadow_pte, spte); > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 37397f6..5b6351e 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -2724,6 +2724,11 @@ static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) > return 0; > } > > +static int svm_dirty_bit_support(void) > +{ > + return 1; > +} > + > static struct kvm_x86_ops svm_x86_ops = { > .cpu_has_kvm_support = has_svm, > .disabled_by_bios = is_disabled, > @@ -2785,6 +2790,8 @@ static struct kvm_x86_ops svm_x86_ops = { > .set_tss_addr = svm_set_tss_addr, > .get_tdp_level = get_npt_level, > .get_mt_mask = svm_get_mt_mask, > + > + .dirty_bit_support = svm_dirty_bit_support, > }; > > static int __init svm_init(void) > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 673bcb3..8903314 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -3774,6 +3774,11 @@ static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) > return ret; > } > > +static int vmx_dirty_bit_support(void) > +{ > + return false; > +} > + > static struct kvm_x86_ops vmx_x86_ops = { > .cpu_has_kvm_support = cpu_has_kvm_support, > .disabled_by_bios = vmx_disabled_by_bios, > @@ -3833,6 +3838,8 @@ static struct kvm_x86_ops vmx_x86_ops = { > .set_tss_addr = vmx_set_tss_addr, > .get_tdp_level = get_ept_level, > .get_mt_mask = vmx_get_mt_mask, > + > + .dirty_bit_support = vmx_dirty_bit_support, > }; > > static int __init vmx_init(void) > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 272e2e8..e06387c 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1963,6 +1963,20 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm, > return 0; > } > > +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) > +{ > + int i; > + > + spin_lock(&kvm->mmu_lock); > + for (i = 0; i < memslot->npages; ++i) { > + if (!test_bit(i, memslot->dirty_bitmap)) { > + if (is_dirty_and_clean_rmapp(kvm, &memslot->rmap[i])) > + set_bit(i, memslot->dirty_bitmap); > + } > + } > + spin_unlock(&kvm->mmu_lock); > +} > + > /* > * Get (and clear) the dirty memory log for a memory slot. > */ > @@ -1982,10 +1996,14 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, > > /* If nothing is dirty, don't bother messing with page tables. */ > if (is_dirty) { > - spin_lock(&kvm->mmu_lock); > - kvm_mmu_slot_remove_write_access(kvm, log->slot); > - spin_unlock(&kvm->mmu_lock); > - kvm_flush_remote_tlbs(kvm); > + if (!kvm_x86_ops->dirty_bit_support()) { > + spin_lock(&kvm->mmu_lock); > + /* remove_write_access() flush the tlb */ > + kvm_mmu_slot_remove_write_access(kvm, log->slot); > + spin_unlock(&kvm->mmu_lock); > + } else { > + kvm_flush_remote_tlbs(kvm); > + } > memslot = &kvm->memslots[log->slot]; > n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; > memset(memslot->dirty_bitmap, 0, n); > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index cdf1279..d1657a3 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -250,6 +250,7 @@ int kvm_dev_ioctl_check_extension(long ext); > > int kvm_get_dirty_log(struct kvm *kvm, > struct kvm_dirty_log *log, int *is_dirty); > +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot); > int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, > struct kvm_dirty_log *log); > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 3046e9c..a876231 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1135,8 +1135,11 @@ int __kvm_set_memory_region(struct kvm *kvm, > } > > /* Free page dirty bitmap if unneeded */ > - if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES)) > + if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES)) { > new.dirty_bitmap = NULL; > + if (old.flags & KVM_MEM_LOG_DIRTY_PAGES) > + kvm_arch_flush_shadow(kvm); > + } Whats this for? The idea of making dirty bit accessible (also can use it to map host ptes read-only, when guest fault is read-only, for KSM (*)) is good. But better first introduce infrastructure to handle dirty bit (making sure the bit is transferred properly), then have logging make use of it. * EPT violations do no transfer fault information to the page fault handler, but its available (there's a vm-exit field). > r = -ENOMEM; > > @@ -1279,6 +1282,7 @@ int kvm_get_dirty_log(struct kvm *kvm, > if (!memslot->dirty_bitmap) > goto out; > > + kvm_arch_get_dirty_log(kvm, memslot); > n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; > > for (i = 0; !any && i < n/sizeof(long); ++i) > -- > 1.5.6.5 > > -- > 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 -- 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
Marcelo Tosatti wrote: > On Wed, Jun 10, 2009 at 07:23:25PM +0300, Izik Eidus wrote: > >> change the dirty page tracking to work with dirty bity instead of page fault. >> right now the dirty page tracking work with the help of page faults, when we >> want to track a page for being dirty, we write protect it and we mark it dirty >> when we have write page fault, this code move into looking at the dirty bit >> of the spte. >> >> Signed-off-by: Izik Eidus <ieidus@redhat.com> >> --- >> arch/ia64/kvm/kvm-ia64.c | 4 +++ >> arch/powerpc/kvm/powerpc.c | 4 +++ >> arch/s390/kvm/kvm-s390.c | 4 +++ >> arch/x86/include/asm/kvm_host.h | 3 ++ >> arch/x86/kvm/mmu.c | 42 ++++++++++++++++++++++++++++++++++++-- >> arch/x86/kvm/svm.c | 7 ++++++ >> arch/x86/kvm/vmx.c | 7 ++++++ >> arch/x86/kvm/x86.c | 26 ++++++++++++++++++++--- >> include/linux/kvm_host.h | 1 + >> virt/kvm/kvm_main.c | 6 ++++- >> 10 files changed, 96 insertions(+), 8 deletions(-) >> >> diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c >> index 3199221..5914128 100644 >> --- a/arch/ia64/kvm/kvm-ia64.c >> +++ b/arch/ia64/kvm/kvm-ia64.c >> @@ -1809,6 +1809,10 @@ void kvm_arch_exit(void) >> kvm_vmm_info = NULL; >> } >> >> +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) >> +{ >> +} >> + >> static int kvm_ia64_sync_dirty_log(struct kvm *kvm, >> struct kvm_dirty_log *log) >> { >> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c >> index 2cf915e..6beb368 100644 >> --- a/arch/powerpc/kvm/powerpc.c >> +++ b/arch/powerpc/kvm/powerpc.c >> @@ -418,6 +418,10 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) >> return -ENOTSUPP; >> } >> > > >> >> > > #ifndef KVM_ARCH_HAVE_DIRTY_LOG > >> +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) >> +{ >> +} >> + >> > #endif > > in virt/kvm/main.c > > > >> index c7b0cc2..8a24149 100644 >> --- a/arch/x86/include/asm/kvm_host.h >> +++ b/arch/x86/include/asm/kvm_host.h >> @@ -527,6 +527,7 @@ struct kvm_x86_ops { >> int (*set_tss_addr)(struct kvm *kvm, unsigned int addr); >> int (*get_tdp_level)(void); >> u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio); >> + int (*dirty_bit_support)(void); >> }; >> >> extern struct kvm_x86_ops *kvm_x86_ops; >> @@ -796,4 +797,6 @@ int kvm_unmap_hva(struct kvm *kvm, unsigned long hva); >> int kvm_age_hva(struct kvm *kvm, unsigned long hva); >> int cpuid_maxphyaddr(struct kvm_vcpu *vcpu); >> >> +int is_dirty_and_clean_rmapp(struct kvm *kvm, unsigned long *rmapp); >> + >> #endif /* _ASM_X86_KVM_HOST_H */ >> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c >> index 809cce0..500e0e2 100644 >> --- a/arch/x86/kvm/mmu.c >> +++ b/arch/x86/kvm/mmu.c >> @@ -140,6 +140,8 @@ module_param(oos_shadow, bool, 0644); >> #define ACC_USER_MASK PT_USER_MASK >> #define ACC_ALL (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK) >> >> +#define SPTE_DONT_DIRTY (1ULL << PT_FIRST_AVAIL_BITS_SHIFT) >> + >> #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level) >> >> struct kvm_rmap_desc { >> @@ -629,6 +631,29 @@ static u64 *rmap_next(struct kvm *kvm, unsigned long *rmapp, u64 *spte) >> return NULL; >> } >> >> +int is_dirty_and_clean_rmapp(struct kvm *kvm, unsigned long *rmapp) >> +{ >> + u64 *spte; >> + int dirty = 0; >> + >> + if (!shadow_dirty_mask) >> + return 0; >> + >> + spte = rmap_next(kvm, rmapp, NULL); >> + while (spte) { >> + if (*spte & PT_DIRTY_MASK) { >> + set_shadow_pte(spte, (*spte &= ~PT_DIRTY_MASK) | >> + SPTE_DONT_DIRTY); >> + dirty = 1; >> + break; >> + } >> + spte = rmap_next(kvm, rmapp, spte); >> + } >> + >> + return dirty; >> +} >> + >> + >> static int rmap_write_protect(struct kvm *kvm, u64 gfn) >> { >> unsigned long *rmapp; >> @@ -1381,11 +1406,17 @@ static int mmu_zap_unsync_children(struct kvm *kvm, >> static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp) >> { >> int ret; >> + int i; >> + >> ++kvm->stat.mmu_shadow_zapped; >> ret = mmu_zap_unsync_children(kvm, sp); >> kvm_mmu_page_unlink_children(kvm, sp); >> kvm_mmu_unlink_parents(kvm, sp); >> kvm_flush_remote_tlbs(kvm); >> + for (i = 0; i < PT64_ENT_PER_PAGE; ++i) { >> + if (sp->spt[i] & PT_DIRTY_MASK) >> + mark_page_dirty(kvm, sp->gfns[i]); >> + } >> > > Also need to transfer dirty bit in other places probably. > Yes, i can think about some other case, but maybe i can avoid it using some trick. > >> if (!sp->role.invalid && !sp->role.direct) >> unaccount_shadowed(kvm, sp->gfn); >> if (sp->unsync) >> @@ -1676,7 +1707,10 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, >> * whether the guest actually used the pte (in order to detect >> * demand paging). >> */ >> - spte = shadow_base_present_pte | shadow_dirty_mask; >> + spte = shadow_base_present_pte; >> + if (!(spte & SPTE_DONT_DIRTY)) >> + spte |= shadow_dirty_mask; >> + >> if (!speculative) >> spte |= shadow_accessed_mask; >> if (!dirty) >> @@ -1725,8 +1759,10 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, >> } >> } >> >> - if (pte_access & ACC_WRITE_MASK) >> - mark_page_dirty(vcpu->kvm, gfn); >> + if (!shadow_dirty_mask) { >> + if (pte_access & ACC_WRITE_MASK) >> + mark_page_dirty(vcpu->kvm, gfn); >> + } >> > > You can avoid the mark_page_dirty if SPTE_DONT_DIRTY? (which is a good idea, > gfn_to_memslot_unaliased and friends show up high in profiling). > This code shouldnt run on anything but EPT, shadow_dirty_mask should be set to zero only on EPT that doesnt have dirty bit tracking, so we still need to mark the page dirty from this context... > >> set_pte: >> set_shadow_pte(shadow_pte, spte); >> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c >> index 37397f6..5b6351e 100644 >> --- a/arch/x86/kvm/svm.c >> +++ b/arch/x86/kvm/svm.c >> @@ -2724,6 +2724,11 @@ static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) >> return 0; >> } >> >> +static int svm_dirty_bit_support(void) >> +{ >> + return 1; >> +} >> + >> static struct kvm_x86_ops svm_x86_ops = { >> .cpu_has_kvm_support = has_svm, >> .disabled_by_bios = is_disabled, >> @@ -2785,6 +2790,8 @@ static struct kvm_x86_ops svm_x86_ops = { >> .set_tss_addr = svm_set_tss_addr, >> .get_tdp_level = get_npt_level, >> .get_mt_mask = svm_get_mt_mask, >> + >> + .dirty_bit_support = svm_dirty_bit_support, >> }; >> >> static int __init svm_init(void) >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >> index 673bcb3..8903314 100644 >> --- a/arch/x86/kvm/vmx.c >> +++ b/arch/x86/kvm/vmx.c >> @@ -3774,6 +3774,11 @@ static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) >> return ret; >> } >> >> +static int vmx_dirty_bit_support(void) >> +{ >> + return false; >> +} >> + >> static struct kvm_x86_ops vmx_x86_ops = { >> .cpu_has_kvm_support = cpu_has_kvm_support, >> .disabled_by_bios = vmx_disabled_by_bios, >> @@ -3833,6 +3838,8 @@ static struct kvm_x86_ops vmx_x86_ops = { >> .set_tss_addr = vmx_set_tss_addr, >> .get_tdp_level = get_ept_level, >> .get_mt_mask = vmx_get_mt_mask, >> + >> + .dirty_bit_support = vmx_dirty_bit_support, >> }; >> >> static int __init vmx_init(void) >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 272e2e8..e06387c 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -1963,6 +1963,20 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm, >> return 0; >> } >> >> +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) >> +{ >> + int i; >> + >> + spin_lock(&kvm->mmu_lock); >> + for (i = 0; i < memslot->npages; ++i) { >> + if (!test_bit(i, memslot->dirty_bitmap)) { >> + if (is_dirty_and_clean_rmapp(kvm, &memslot->rmap[i])) >> + set_bit(i, memslot->dirty_bitmap); >> + } >> + } >> + spin_unlock(&kvm->mmu_lock); >> +} >> + >> /* >> * Get (and clear) the dirty memory log for a memory slot. >> */ >> @@ -1982,10 +1996,14 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, >> >> /* If nothing is dirty, don't bother messing with page tables. */ >> if (is_dirty) { >> - spin_lock(&kvm->mmu_lock); >> - kvm_mmu_slot_remove_write_access(kvm, log->slot); >> - spin_unlock(&kvm->mmu_lock); >> - kvm_flush_remote_tlbs(kvm); >> + if (!kvm_x86_ops->dirty_bit_support()) { >> + spin_lock(&kvm->mmu_lock); >> + /* remove_write_access() flush the tlb */ >> + kvm_mmu_slot_remove_write_access(kvm, log->slot); >> + spin_unlock(&kvm->mmu_lock); >> + } else { >> + kvm_flush_remote_tlbs(kvm); >> + } >> memslot = &kvm->memslots[log->slot]; >> n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; >> memset(memslot->dirty_bitmap, 0, n); >> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h >> index cdf1279..d1657a3 100644 >> --- a/include/linux/kvm_host.h >> +++ b/include/linux/kvm_host.h >> @@ -250,6 +250,7 @@ int kvm_dev_ioctl_check_extension(long ext); >> >> int kvm_get_dirty_log(struct kvm *kvm, >> struct kvm_dirty_log *log, int *is_dirty); >> +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot); >> int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, >> struct kvm_dirty_log *log); >> >> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c >> index 3046e9c..a876231 100644 >> --- a/virt/kvm/kvm_main.c >> +++ b/virt/kvm/kvm_main.c >> @@ -1135,8 +1135,11 @@ int __kvm_set_memory_region(struct kvm *kvm, >> } >> >> /* Free page dirty bitmap if unneeded */ >> - if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES)) >> + if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES)) { >> new.dirty_bitmap = NULL; >> + if (old.flags & KVM_MEM_LOG_DIRTY_PAGES) >> + kvm_arch_flush_shadow(kvm); >> + } >> > > Whats this for? > We have added all this SPTE_DONT_DIRTY..., when we stop dirty bit tracking, we want to continue setting the dirty bit for the spte inside set_spte(), so writing to the page would be faster.... > The idea of making dirty bit accessible (also can use it to map host > ptes read-only, when guest fault is read-only, for KSM (*)) is good. But > better first introduce infrastructure to handle dirty bit (making sure > the bit is transferred properly), then have logging make use of it. > ???, I dont understand it much, it mean you want to continue trying walking in that direction of the patch? or you want some other way? > * EPT violations do no transfer fault information to the page fault > handler, but its available (there's a vm-exit field). > EPT in this patch, run as before, (using page faults with mark_page_dirty() inside set_spte()) > >> r = -ENOMEM; >> >> @@ -1279,6 +1282,7 @@ int kvm_get_dirty_log(struct kvm *kvm, >> if (!memslot->dirty_bitmap) >> goto out; >> >> + kvm_arch_get_dirty_log(kvm, memslot); >> n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; >> >> for (i = 0; !any && i < n/sizeof(long); ++i) >> -- >> 1.5.6.5 >> >> -- >> 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 >> Thanks :). -- 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
Izik Eidus wrote: > Marcelo Tosatti wrote: > >>> >>> >>> /* Free page dirty bitmap if unneeded */ >>> - if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES)) >>> + if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES)) { >>> new.dirty_bitmap = NULL; >>> + if (old.flags & KVM_MEM_LOG_DIRTY_PAGES) >>> + kvm_arch_flush_shadow(kvm); >>> + } >>> >> >> Whats this for? >> > > We have added all this SPTE_DONT_DIRTY..., when we stop dirty bit > tracking, we want to continue setting the dirty bit for the spte > inside set_spte(), so writing to the page would be faster.... Another way would be doing something like kvm_arch_clean_dont_dirty(), might be better than flushing the whole shadow page tables. -- 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
On Thu, Jun 11, 2009 at 02:57:02AM +0300, Izik Eidus wrote: >> You can avoid the mark_page_dirty if SPTE_DONT_DIRTY? (which is a good idea, >> gfn_to_memslot_unaliased and friends show up high in profiling). >> > > This code shouldnt run on anything but EPT, shadow_dirty_mask should be > set to zero only on EPT that doesnt have dirty bit tracking, so we still > need to mark the page dirty from this context... Right, i misunderstood you were not skipping it for kvm_x86_ops->have_dirty_bit() case. >>> --- a/virt/kvm/kvm_main.c >>> +++ b/virt/kvm/kvm_main.c >>> @@ -1135,8 +1135,11 @@ int __kvm_set_memory_region(struct kvm *kvm, >>> } >>> /* Free page dirty bitmap if unneeded */ >>> - if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES)) >>> + if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES)) { >>> new.dirty_bitmap = NULL; >>> + if (old.flags & KVM_MEM_LOG_DIRTY_PAGES) >>> + kvm_arch_flush_shadow(kvm); >>> + } >>> >> >> Whats this for? >> > > We have added all this SPTE_DONT_DIRTY..., when we stop dirty bit > tracking, we want to continue setting the dirty bit for the spte inside > set_spte(), so writing to the page would be faster.... Right... so instead of using kvm_arch_flush_shadow make a "kvm_arch_stop_dirty_logging(kvm, slot)", and clear the SPTE_DONT_DIRTY bits? > >> The idea of making dirty bit accessible (also can use it to map host >> ptes read-only, when guest fault is read-only, for KSM (*)) is good. But >> better first introduce infrastructure to handle dirty bit (making sure >> the bit is transferred properly), then have logging make use of it. >> > > ???, I dont understand it much, it mean you want to continue trying > walking in that direction of the patch? or you want some other way? What i'm saying is with shadow and NPT (i believe) you can mark a spte writable but not dirty, which gives you the ability to know whether certain pages have been dirtied. Should be ok todo that with shadow, as long as the gpte is already dirty, right? So: - guest create writable pte - guest write fault on that pte - vmexit - write dirty bit to gpte - create writable spte -> from this point on, you can create a writable spte which is not dirtied, and use the dirty bit to know whether a page has been written to? And unless i'm mistaken NPT gives you that for free since the hw updates the spte with accessed/dirty bits. Maybe this is a stupid idea. >> * EPT violations do no transfer fault information to the page fault >> handler, but its available (there's a vm-exit field). >> > > EPT in this patch, run as before, (using page faults with > mark_page_dirty() inside set_spte()) Right, i was talking about gup(write=0) when guest fault is read-only to relief KSM of wrprotecting host ptes, but that is quite different. >> >>> r = -ENOMEM; >>> @@ -1279,6 +1282,7 @@ int kvm_get_dirty_log(struct kvm *kvm, >>> if (!memslot->dirty_bitmap) >>> goto out; >>> + kvm_arch_get_dirty_log(kvm, memslot); >>> n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; >>> for (i = 0; !any && i < n/sizeof(long); ++i) >>> -- >>> 1.5.6.5 >>> >>> -- >>> 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 >>> > > > Thanks :). -- 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
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Izik Eidus wrote: > + if (!kvm_x86_ops->dirty_bit_support()) { > + spin_lock(&kvm->mmu_lock); > + /* remove_write_access() flush the tlb */ > + kvm_mmu_slot_remove_write_access(kvm, log->slot); > + spin_unlock(&kvm->mmu_lock); > + } else { > + kvm_flush_remote_tlbs(kvm); It might not correspond to the common style, but I think a callback function ->dirty_bit_support is overkill. This is a function pointer the compiler cannot see through. Hence it's an indirect function call. But the implementation is always a simple yes/no (it seems). Indirect calls are rather expensive (most of the time they cannot be predicted right). Why not instead have a read-only data constants and have an inline function test that value? It means no function call and only one data access. Also, you're inconsistent in the use of integers and true/false in the implementations of this function. Either use 0/1 or false/true. - -- ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ■-----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEARECAAYFAkowv08ACgkQ2ijCOnn/RHR71ACdH3xr3XPnCLgsMMwdTawfehEN vs4An2DlErhU6SeanSYVIyP3eLB4sjsz =UZ32 -----END PGP SIGNATURE----- -- 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
Izik Eidus wrote: > change the dirty page tracking to work with dirty bity instead of page fault. > right now the dirty page tracking work with the help of page faults, when we > want to track a page for being dirty, we write protect it and we mark it dirty > when we have write page fault, this code move into looking at the dirty bit > of the spte. > > I'm concerned about performance during the later stages of live migration. Even if only 1000 pages are dirty, you still have to look at 2,000,000 or more ptes (for an 8GB guest). That's a lot of overhead. I think we need to use the page table hierarchy, write protect the upper page table so we know which page tables we need to look at. > +int is_dirty_and_clean_rmapp(struct kvm *kvm, unsigned long *rmapp) > +{ > + u64 *spte; > + int dirty = 0; > + > + if (!shadow_dirty_mask) > + return 0; > + > + spte = rmap_next(kvm, rmapp, NULL); > + while (spte) { > + if (*spte & PT_DIRTY_MASK) { > + set_shadow_pte(spte, (*spte &= ~PT_DIRTY_MASK) | > + SPTE_DONT_DIRTY); > Keep using shadow_dirty_mask here for consistency. > kvm_flush_remote_tlbs(kvm); > + for (i = 0; i < PT64_ENT_PER_PAGE; ++i) { > + if (sp->spt[i] & PT_DIRTY_MASK) > + mark_page_dirty(kvm, sp->gfns[i]); > + } > shadow_dirty_mask. > @@ -2785,6 +2790,8 @@ static struct kvm_x86_ops svm_x86_ops = { > .set_tss_addr = svm_set_tss_addr, > .get_tdp_level = get_npt_level, > .get_mt_mask = svm_get_mt_mask, > + > + .dirty_bit_support = svm_dirty_bit_support, > }; > Just use shadow_dirty_mask != 0. > > +static int vmx_dirty_bit_support(void) > +{ > + return false; > +} > It's false only when ept is enabled.
Ulrich Drepper wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Izik Eidus wrote: > >> + if (!kvm_x86_ops->dirty_bit_support()) { >> + spin_lock(&kvm->mmu_lock); >> + /* remove_write_access() flush the tlb */ >> + kvm_mmu_slot_remove_write_access(kvm, log->slot); >> + spin_unlock(&kvm->mmu_lock); >> + } else { >> + kvm_flush_remote_tlbs(kvm); >> > > Hi. > It might not correspond to the common style, but I think a callback > function ->dirty_bit_support is overkill. This is a function pointer > the compiler cannot see through. Hence it's an indirect function call. > But the implementation is always a simple yes/no (it seems). Indirect > calls are rather expensive (most of the time they cannot be predicted > right). > This function pointer will be called once every ioctl to get the dirty bit tracking, so i dont think it is a big issue (normal 30 times a sec) > Why not instead have a read-only data constants and have an inline > function test that value? It means no function call and only one data > access. > May be relevent, but i dont sure if it is needed optimization for this patch consider the amount of time ->dirty_bit_support() will be called > > Also, you're inconsistent in the use of integers and true/false in the > implementations of this function. Either use 0/1 or false/true. > I will fix it, thanks. > - -- > ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ■> -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.9 (GNU/Linux) > > iEYEARECAAYFAkowv08ACgkQ2ijCOnn/RHR71ACdH3xr3XPnCLgsMMwdTawfehEN > vs4An2DlErhU6SeanSYVIyP3eLB4sjsz > =UZ32 > -----END PGP SIGNATURE----- > -- 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
Avi Kivity wrote: > Izik Eidus wrote: >> change the dirty page tracking to work with dirty bity instead of >> page fault. >> right now the dirty page tracking work with the help of page faults, >> when we >> want to track a page for being dirty, we write protect it and we mark >> it dirty >> when we have write page fault, this code move into looking at the >> dirty bit >> of the spte. >> >> > > I'm concerned about performance during the later stages of live > migration. Even if only 1000 pages are dirty, you still have to look > at 2,000,000 or more ptes (for an 8GB guest). That's a lot of overhead. > > I think we need to use the page table hierarchy, write protect the > upper page table so we know which page tables we need to look at. > > Great idea, so i add another bitmap for the page directory? >> >> +static int vmx_dirty_bit_support(void) >> +{ >> + return false; >> +} >> > > It's false only when ept is enabled. > Yea, that i found out already.... -- 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
Izik Eidus wrote: > Avi Kivity wrote: >> Izik Eidus wrote: >>> change the dirty page tracking to work with dirty bity instead of >>> page fault. >>> right now the dirty page tracking work with the help of page faults, >>> when we >>> want to track a page for being dirty, we write protect it and we >>> mark it dirty >>> when we have write page fault, this code move into looking at the >>> dirty bit >>> of the spte. >>> >>> >> >> I'm concerned about performance during the later stages of live >> migration. Even if only 1000 pages are dirty, you still have to look >> at 2,000,000 or more ptes (for an 8GB guest). That's a lot of overhead. >> >> I think we need to use the page table hierarchy, write protect the >> upper page table so we know which page tables we need to look at. >> >> > > Great idea, so i add another bitmap for the page directory? No, why? You need to drop write access to the shadow root ptes. When you get a fault, restore write access to the root ptes, but drop access from the L3 ptes, and so on until you reach the L1 ptes. There you clear the dirty bits, and add the page to a list of pages that need to be checked for dirty bits. This way you only check ptes that have a chance to be dirty. I'm not sure that will be faster, but there's a good chance.
Marcelo Tosatti wrote: > > > What i'm saying is with shadow and NPT (i believe) you can mark a spte > writable but not dirty, which gives you the ability to know whether > certain pages have been dirtied. > Isnt this what this patch is doing? > Should be ok todo that with shadow, as long as the gpte is already > dirty, right? So: > > - guest create writable pte > - guest write fault on that pte > - vmexit > - write dirty bit to gpte > - create writable spte > -> > > from this point on, you can create a writable spte which is not dirtied, > and use the dirty bit to know whether a page has been written to? > > And unless i'm mistaken NPT gives you that for free since the hw updates > the spte with accessed/dirty bits. > Yes > Maybe this is a stupid idea. > I dont sure if i am missing it, or if this what i tried to do with this patch. > >>> * EPT violations do no transfer fault information to the page fault >>> handler, but its available (there's a vm-exit field). >>> >>> >> EPT in this patch, run as before, (using page faults with >> mark_page_dirty() inside set_spte()) >> > > Right, i was talking about gup(write=0) when guest fault is read-only to > relief KSM of wrprotecting host ptes, but that is quite different. > > >>> >>> >>>> r = -ENOMEM; >>>> @@ -1279,6 +1282,7 @@ int kvm_get_dirty_log(struct kvm *kvm, >>>> if (!memslot->dirty_bitmap) >>>> goto out; >>>> + kvm_arch_get_dirty_log(kvm, memslot); >>>> n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; >>>> for (i = 0; !any && i < n/sizeof(long); ++i) >>>> -- >>>> 1.5.6.5 >>>> >>>> -- >>>> 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 >>>> >>>> >> Thanks :). >> -- 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
On Thu, Jun 11, 2009 at 02:27:46PM +0300, Izik Eidus wrote: > Marcelo Tosatti wrote: >> >> >> What i'm saying is with shadow and NPT (i believe) you can mark a spte >> writable but not dirty, which gives you the ability to know whether >> certain pages have been dirtied. >> > > Isnt this what this patch is doing? Yes, was confused for some reason i don't remember. So making the dirty bit available to the host is a good idea, but would have to check things like faults on out of sync pagetables (where the guest dirty bit might be cleared in parallel, maybe its ok but not sure), verify transfer of dirty bit when zapping is consistent everywhere, etc. So it would be nicer to introduce an optimization to the way dirty bit info is acquired, then you use that to optimize kvm's dirty log ioctl. The link with KSM was that you can consult this dirty info, which is fast, to know if content of pages has changed. But it maybe useless, don't know. -- 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
Marcelo Tosatti wrote: > On Thu, Jun 11, 2009 at 02:27:46PM +0300, Izik Eidus wrote: > >> Marcelo Tosatti wrote: >> >>> What i'm saying is with shadow and NPT (i believe) you can mark a spte >>> writable but not dirty, which gives you the ability to know whether >>> certain pages have been dirtied. >>> >>> >> Isnt this what this patch is doing? >> > > Yes, was confused for some reason i don't remember. > > So making the dirty bit available to the host is a good idea, but would > have to check things like faults on out of sync pagetables (where > the guest dirty bit might be cleared in parallel, maybe its ok but > not sure), verify transfer of dirty bit when zapping is consistent > everywhere, etc. > I am looking on the host sptes, not the guest emulated page tables, when the guest clean its dirty bit, we dont clean it from the spte, or am i wrong? When we zap the spte, i transfer the dirty bit into the bitmap in case of SPTE_DONT_DIRTY..., But Avi, pointed out that in case of live migration, it might be overkill to walk all the sptes in the system, so maybe we want to add page fault from the page directory (would be write protected, or if it cant be write protected at least notpresent), and then scan only sptes that inside this "write protected" page tables... You have some ideas for this case? > So it would be nicer to introduce an optimization to the way dirty bit > info is acquired, then you use that to optimize kvm's dirty log ioctl. > > The link with KSM was that you can consult this dirty info, which is > fast, to know if content of pages has changed. But it maybe useless, > don't know. > > It sure can help for ksm as we calc sometimes jhash of the page to know if the page content was changed, but i afraid that starting to clean the dirty bit that will need tlbflush, plus taking the mmu_lock to walk the sptes, maybe will save ksm some cpu, but might hurt kvm, we will have to check this... -- 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/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c index 3199221..5914128 100644 --- a/arch/ia64/kvm/kvm-ia64.c +++ b/arch/ia64/kvm/kvm-ia64.c @@ -1809,6 +1809,10 @@ void kvm_arch_exit(void) kvm_vmm_info = NULL; } +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) +{ +} + static int kvm_ia64_sync_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) { diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c index 2cf915e..6beb368 100644 --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -418,6 +418,10 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) return -ENOTSUPP; } +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) +{ +} + long kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 981ab04..ab6f115 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -130,6 +130,10 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, return 0; } +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) +{ +} + long kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index c7b0cc2..8a24149 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -527,6 +527,7 @@ struct kvm_x86_ops { int (*set_tss_addr)(struct kvm *kvm, unsigned int addr); int (*get_tdp_level)(void); u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio); + int (*dirty_bit_support)(void); }; extern struct kvm_x86_ops *kvm_x86_ops; @@ -796,4 +797,6 @@ int kvm_unmap_hva(struct kvm *kvm, unsigned long hva); int kvm_age_hva(struct kvm *kvm, unsigned long hva); int cpuid_maxphyaddr(struct kvm_vcpu *vcpu); +int is_dirty_and_clean_rmapp(struct kvm *kvm, unsigned long *rmapp); + #endif /* _ASM_X86_KVM_HOST_H */ diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 809cce0..500e0e2 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -140,6 +140,8 @@ module_param(oos_shadow, bool, 0644); #define ACC_USER_MASK PT_USER_MASK #define ACC_ALL (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK) +#define SPTE_DONT_DIRTY (1ULL << PT_FIRST_AVAIL_BITS_SHIFT) + #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level) struct kvm_rmap_desc { @@ -629,6 +631,29 @@ static u64 *rmap_next(struct kvm *kvm, unsigned long *rmapp, u64 *spte) return NULL; } +int is_dirty_and_clean_rmapp(struct kvm *kvm, unsigned long *rmapp) +{ + u64 *spte; + int dirty = 0; + + if (!shadow_dirty_mask) + return 0; + + spte = rmap_next(kvm, rmapp, NULL); + while (spte) { + if (*spte & PT_DIRTY_MASK) { + set_shadow_pte(spte, (*spte &= ~PT_DIRTY_MASK) | + SPTE_DONT_DIRTY); + dirty = 1; + break; + } + spte = rmap_next(kvm, rmapp, spte); + } + + return dirty; +} + + static int rmap_write_protect(struct kvm *kvm, u64 gfn) { unsigned long *rmapp; @@ -1381,11 +1406,17 @@ static int mmu_zap_unsync_children(struct kvm *kvm, static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp) { int ret; + int i; + ++kvm->stat.mmu_shadow_zapped; ret = mmu_zap_unsync_children(kvm, sp); kvm_mmu_page_unlink_children(kvm, sp); kvm_mmu_unlink_parents(kvm, sp); kvm_flush_remote_tlbs(kvm); + for (i = 0; i < PT64_ENT_PER_PAGE; ++i) { + if (sp->spt[i] & PT_DIRTY_MASK) + mark_page_dirty(kvm, sp->gfns[i]); + } if (!sp->role.invalid && !sp->role.direct) unaccount_shadowed(kvm, sp->gfn); if (sp->unsync) @@ -1676,7 +1707,10 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, * whether the guest actually used the pte (in order to detect * demand paging). */ - spte = shadow_base_present_pte | shadow_dirty_mask; + spte = shadow_base_present_pte; + if (!(spte & SPTE_DONT_DIRTY)) + spte |= shadow_dirty_mask; + if (!speculative) spte |= shadow_accessed_mask; if (!dirty) @@ -1725,8 +1759,10 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, } } - if (pte_access & ACC_WRITE_MASK) - mark_page_dirty(vcpu->kvm, gfn); + if (!shadow_dirty_mask) { + if (pte_access & ACC_WRITE_MASK) + mark_page_dirty(vcpu->kvm, gfn); + } set_pte: set_shadow_pte(shadow_pte, spte); diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 37397f6..5b6351e 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -2724,6 +2724,11 @@ static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) return 0; } +static int svm_dirty_bit_support(void) +{ + return 1; +} + static struct kvm_x86_ops svm_x86_ops = { .cpu_has_kvm_support = has_svm, .disabled_by_bios = is_disabled, @@ -2785,6 +2790,8 @@ static struct kvm_x86_ops svm_x86_ops = { .set_tss_addr = svm_set_tss_addr, .get_tdp_level = get_npt_level, .get_mt_mask = svm_get_mt_mask, + + .dirty_bit_support = svm_dirty_bit_support, }; static int __init svm_init(void) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 673bcb3..8903314 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3774,6 +3774,11 @@ static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) return ret; } +static int vmx_dirty_bit_support(void) +{ + return false; +} + static struct kvm_x86_ops vmx_x86_ops = { .cpu_has_kvm_support = cpu_has_kvm_support, .disabled_by_bios = vmx_disabled_by_bios, @@ -3833,6 +3838,8 @@ static struct kvm_x86_ops vmx_x86_ops = { .set_tss_addr = vmx_set_tss_addr, .get_tdp_level = get_ept_level, .get_mt_mask = vmx_get_mt_mask, + + .dirty_bit_support = vmx_dirty_bit_support, }; static int __init vmx_init(void) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 272e2e8..e06387c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1963,6 +1963,20 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm, return 0; } +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) +{ + int i; + + spin_lock(&kvm->mmu_lock); + for (i = 0; i < memslot->npages; ++i) { + if (!test_bit(i, memslot->dirty_bitmap)) { + if (is_dirty_and_clean_rmapp(kvm, &memslot->rmap[i])) + set_bit(i, memslot->dirty_bitmap); + } + } + spin_unlock(&kvm->mmu_lock); +} + /* * Get (and clear) the dirty memory log for a memory slot. */ @@ -1982,10 +1996,14 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, /* If nothing is dirty, don't bother messing with page tables. */ if (is_dirty) { - spin_lock(&kvm->mmu_lock); - kvm_mmu_slot_remove_write_access(kvm, log->slot); - spin_unlock(&kvm->mmu_lock); - kvm_flush_remote_tlbs(kvm); + if (!kvm_x86_ops->dirty_bit_support()) { + spin_lock(&kvm->mmu_lock); + /* remove_write_access() flush the tlb */ + kvm_mmu_slot_remove_write_access(kvm, log->slot); + spin_unlock(&kvm->mmu_lock); + } else { + kvm_flush_remote_tlbs(kvm); + } memslot = &kvm->memslots[log->slot]; n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; memset(memslot->dirty_bitmap, 0, n); diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index cdf1279..d1657a3 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -250,6 +250,7 @@ int kvm_dev_ioctl_check_extension(long ext); int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log, int *is_dirty); +void kvm_arch_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot); int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 3046e9c..a876231 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1135,8 +1135,11 @@ int __kvm_set_memory_region(struct kvm *kvm, } /* Free page dirty bitmap if unneeded */ - if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES)) + if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES)) { new.dirty_bitmap = NULL; + if (old.flags & KVM_MEM_LOG_DIRTY_PAGES) + kvm_arch_flush_shadow(kvm); + } r = -ENOMEM; @@ -1279,6 +1282,7 @@ int kvm_get_dirty_log(struct kvm *kvm, if (!memslot->dirty_bitmap) goto out; + kvm_arch_get_dirty_log(kvm, memslot); n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; for (i = 0; !any && i < n/sizeof(long); ++i)
change the dirty page tracking to work with dirty bity instead of page fault. right now the dirty page tracking work with the help of page faults, when we want to track a page for being dirty, we write protect it and we mark it dirty when we have write page fault, this code move into looking at the dirty bit of the spte. Signed-off-by: Izik Eidus <ieidus@redhat.com> --- arch/ia64/kvm/kvm-ia64.c | 4 +++ arch/powerpc/kvm/powerpc.c | 4 +++ arch/s390/kvm/kvm-s390.c | 4 +++ arch/x86/include/asm/kvm_host.h | 3 ++ arch/x86/kvm/mmu.c | 42 ++++++++++++++++++++++++++++++++++++-- arch/x86/kvm/svm.c | 7 ++++++ arch/x86/kvm/vmx.c | 7 ++++++ arch/x86/kvm/x86.c | 26 ++++++++++++++++++++--- include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 6 ++++- 10 files changed, 96 insertions(+), 8 deletions(-)