| Message ID | 20121218162647.009f468e.yoshikawa_takuya_b1@lab.ntt.co.jp (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Dec 18, 2012 at 04:26:47PM +0900, Takuya Yoshikawa wrote: > This is needed to make kvm_mmu_slot_remove_write_access() rmap based: > otherwise we may end up using invalid rmap's. > > Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> > --- > arch/x86/kvm/x86.c | 9 ++++++++- > virt/kvm/kvm_main.c | 1 - > 2 files changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 1c9c834..9451efa 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -6897,7 +6897,14 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, > spin_lock(&kvm->mmu_lock); > if (nr_mmu_pages) > kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages); > - kvm_mmu_slot_remove_write_access(kvm, mem->slot); > + /* > + * Write protect all pages for dirty logging. > + * Existing largepage mappings are destroyed here and new ones will > + * not be created until the end of the logging. > + */ > + if ((mem->flags & KVM_MEM_LOG_DIRTY_PAGES) && > + !(old.flags & KVM_MEM_LOG_DIRTY_PAGES)) > + kvm_mmu_slot_remove_write_access(kvm, mem->slot); We should not check old slot flags here or at least check that old.npages is not zero. Userspace may delete a slot using old flags, then, if new memslot is created with dirty log enabled, it will not be protected. > spin_unlock(&kvm->mmu_lock); > /* > * If memory slot is created, or moved, we need to clear all > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index bd31096..0ef5daa 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -805,7 +805,6 @@ int __kvm_set_memory_region(struct kvm *kvm, > if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) { > if (kvm_create_dirty_bitmap(&new) < 0) > goto out_free; > - /* destroy any largepage mappings for dirty tracking */ > } > > if (!npages || base_gfn != old.base_gfn) { > -- > 1.7.5.4 -- Gleb. -- 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 Mon, 24 Dec 2012 15:27:17 +0200 Gleb Natapov <gleb@redhat.com> wrote: > > @@ -6897,7 +6897,14 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, > > spin_lock(&kvm->mmu_lock); > > if (nr_mmu_pages) > > kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages); > > - kvm_mmu_slot_remove_write_access(kvm, mem->slot); > > + /* > > + * Write protect all pages for dirty logging. > > + * Existing largepage mappings are destroyed here and new ones will > > + * not be created until the end of the logging. > > + */ > > + if ((mem->flags & KVM_MEM_LOG_DIRTY_PAGES) && > > + !(old.flags & KVM_MEM_LOG_DIRTY_PAGES)) > > + kvm_mmu_slot_remove_write_access(kvm, mem->slot); > We should not check old slot flags here or at least check that > old.npages is not zero. Userspace may delete a slot using old flags, > then, if new memslot is created with dirty log enabled, it will not be > protected. The flag, KVM_MEM_LOG_DIRTY_PAGES, is explicitely cleared when we delete a slot to free dirty_bitmap: if (!npages) mem->flags &= ~KVM_MEM_LOG_DIRTY_PAGES; So when old.npages is not zero, the second condition must be true. Other parts are doing "if (!slot->dirty_bitmap)" to see if the slot is in dirty logging mode. If you prefer, we can do the same here. Thanks, Takuya -- 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 Tue, Dec 25, 2012 at 01:08:40PM +0900, Takuya Yoshikawa wrote: > On Mon, 24 Dec 2012 15:27:17 +0200 > Gleb Natapov <gleb@redhat.com> wrote: > > > > @@ -6897,7 +6897,14 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, > > > spin_lock(&kvm->mmu_lock); > > > if (nr_mmu_pages) > > > kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages); > > > - kvm_mmu_slot_remove_write_access(kvm, mem->slot); > > > + /* > > > + * Write protect all pages for dirty logging. > > > + * Existing largepage mappings are destroyed here and new ones will > > > + * not be created until the end of the logging. > > > + */ > > > + if ((mem->flags & KVM_MEM_LOG_DIRTY_PAGES) && > > > + !(old.flags & KVM_MEM_LOG_DIRTY_PAGES)) > > > + kvm_mmu_slot_remove_write_access(kvm, mem->slot); > > We should not check old slot flags here or at least check that > > old.npages is not zero. Userspace may delete a slot using old flags, > > then, if new memslot is created with dirty log enabled, it will not be > > protected. > > The flag, KVM_MEM_LOG_DIRTY_PAGES, is explicitely cleared when we > delete a slot to free dirty_bitmap: > > if (!npages) > mem->flags &= ~KVM_MEM_LOG_DIRTY_PAGES; > > So when old.npages is not zero, the second condition must be true. > Right. I was looking for where it is cleared and missed that. > Other parts are doing "if (!slot->dirty_bitmap)" to see if the slot > is in dirty logging mode. If you prefer, we can do the same here. > Does not matter to me. If you think it will be more consistent do it. -- Gleb. -- 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 Tue, 25 Dec 2012 07:05:55 +0200 Gleb Natapov <gleb@redhat.com> wrote: > > Other parts are doing "if (!slot->dirty_bitmap)" to see if the slot > > is in dirty logging mode. If you prefer, we can do the same here. > > > Does not matter to me. If you think it will be more consistent do it. No preference at the moment. But since .dirty_bitmap and .rmap may be changed to control free_physmem(new, old) behaviour, I'll keep the code as is. I'll send some patches to clean up the current "mem, new, old, slot" games in __kvm_set_memory_region() later. I was confused many times by these. In addition, passing old slot by value to kvm_arch_commit_memory_region() should be fixed as well. The structure is too big to copy. Thanks, Takuya -- 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 Tue, Dec 18, 2012 at 04:26:47PM +0900, Takuya Yoshikawa wrote: > This is needed to make kvm_mmu_slot_remove_write_access() rmap based: > otherwise we may end up using invalid rmap's. > > Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> Why? memslot->arch.rmap[] has been properly allocated at this point. > --- > arch/x86/kvm/x86.c | 9 ++++++++- > virt/kvm/kvm_main.c | 1 - > 2 files changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 1c9c834..9451efa 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -6897,7 +6897,14 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, > spin_lock(&kvm->mmu_lock); > if (nr_mmu_pages) > kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages); > - kvm_mmu_slot_remove_write_access(kvm, mem->slot); > + /* > + * Write protect all pages for dirty logging. > + * Existing largepage mappings are destroyed here and new ones will > + * not be created until the end of the logging. > + */ > + if ((mem->flags & KVM_MEM_LOG_DIRTY_PAGES) && > + !(old.flags & KVM_MEM_LOG_DIRTY_PAGES)) > + kvm_mmu_slot_remove_write_access(kvm, mem->slot); > spin_unlock(&kvm->mmu_lock); > /* > * If memory slot is created, or moved, we need to clear all > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index bd31096..0ef5daa 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -805,7 +805,6 @@ int __kvm_set_memory_region(struct kvm *kvm, > if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) { > if (kvm_create_dirty_bitmap(&new) < 0) > goto out_free; > - /* destroy any largepage mappings for dirty tracking */ > } > > if (!npages || base_gfn != old.base_gfn) { > -- > 1.7.5.4 > > -- > 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
On Mon, Jan 07, 2013 at 06:11:46PM -0200, Marcelo Tosatti wrote: > On Tue, Dec 18, 2012 at 04:26:47PM +0900, Takuya Yoshikawa wrote: > > This is needed to make kvm_mmu_slot_remove_write_access() rmap based: > > otherwise we may end up using invalid rmap's. > > > > Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> > > Why? memslot->arch.rmap[] has been properly allocated at this point. > FWIW a long time ago in a galaxy far, far away there was a check for KVM_MEM_LOG_DIRTY_PAGES before call to kvm_mmu_slot_remove_write_access(), but it was removed by 90cb0529dd230548a7, as far as I can tell, accidentally. > > --- > > arch/x86/kvm/x86.c | 9 ++++++++- > > virt/kvm/kvm_main.c | 1 - > > 2 files changed, 8 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index 1c9c834..9451efa 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -6897,7 +6897,14 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, > > spin_lock(&kvm->mmu_lock); > > if (nr_mmu_pages) > > kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages); > > - kvm_mmu_slot_remove_write_access(kvm, mem->slot); > > + /* > > + * Write protect all pages for dirty logging. > > + * Existing largepage mappings are destroyed here and new ones will > > + * not be created until the end of the logging. > > + */ > > + if ((mem->flags & KVM_MEM_LOG_DIRTY_PAGES) && > > + !(old.flags & KVM_MEM_LOG_DIRTY_PAGES)) > > + kvm_mmu_slot_remove_write_access(kvm, mem->slot); > > spin_unlock(&kvm->mmu_lock); > > /* > > * If memory slot is created, or moved, we need to clear all > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index bd31096..0ef5daa 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -805,7 +805,6 @@ int __kvm_set_memory_region(struct kvm *kvm, > > if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) { > > if (kvm_create_dirty_bitmap(&new) < 0) > > goto out_free; > > - /* destroy any largepage mappings for dirty tracking */ > > } > > > > if (!npages || base_gfn != old.base_gfn) { > > -- > > 1.7.5.4 > > > > -- > > 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 -- Gleb. -- 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/x86.c b/arch/x86/kvm/x86.c index 1c9c834..9451efa 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6897,7 +6897,14 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, spin_lock(&kvm->mmu_lock); if (nr_mmu_pages) kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages); - kvm_mmu_slot_remove_write_access(kvm, mem->slot); + /* + * Write protect all pages for dirty logging. + * Existing largepage mappings are destroyed here and new ones will + * not be created until the end of the logging. + */ + if ((mem->flags & KVM_MEM_LOG_DIRTY_PAGES) && + !(old.flags & KVM_MEM_LOG_DIRTY_PAGES)) + kvm_mmu_slot_remove_write_access(kvm, mem->slot); spin_unlock(&kvm->mmu_lock); /* * If memory slot is created, or moved, we need to clear all diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index bd31096..0ef5daa 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -805,7 +805,6 @@ int __kvm_set_memory_region(struct kvm *kvm, if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) { if (kvm_create_dirty_bitmap(&new) < 0) goto out_free; - /* destroy any largepage mappings for dirty tracking */ } if (!npages || base_gfn != old.base_gfn) {
This is needed to make kvm_mmu_slot_remove_write_access() rmap based: otherwise we may end up using invalid rmap's. Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> --- arch/x86/kvm/x86.c | 9 ++++++++- virt/kvm/kvm_main.c | 1 - 2 files changed, 8 insertions(+), 2 deletions(-)