| Message ID | 1364810209-25954-7-git-send-email-xiaoguangrong@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Apr 01, 2013 at 05:56:49PM +0800, Xiao Guangrong wrote: > Then it has chance to trigger mmio generation number wrap-around > > Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/mmu.c | 8 ++++++++ > virt/kvm/kvm_main.c | 6 ++++++ > 3 files changed, 15 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 6c1e642..4e1f7cb 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -767,6 +767,7 @@ void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, > struct kvm_memory_slot *slot, > gfn_t gfn_offset, unsigned long mask); > void kvm_mmu_zap_all(struct kvm *kvm); > +void kvm_arch_init_generation(struct kvm *kvm); > void kvm_mmu_invalid_mmio_sptes(struct kvm *kvm); > unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm); > void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages); > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index d314e21..dcc059c 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -4279,6 +4279,14 @@ restart: > spin_unlock(&kvm->mmu_lock); > } > > +void kvm_arch_init_generation(struct kvm *kvm) > +{ > + mutex_lock(&kvm->slots_lock); > + /* It is easier to trigger mmio generation-number wrap-around. */ > + kvm_memslots(kvm)->generation = MMIO_MAX_GEN - 13; kvm_memslots(kvm)->generation should never overflow since (read|write)_cached mechanism does not handle it. Initialising it to anything but 0 makes overflow more likely. You can hide mmio overflow trick in kvm_current_mmio_generation(): static unsigned int kvm_current_mmio_generation(struct kvm *kvm) { return (kvm_memslots(kvm)->generation + MMIO_MAX_GEN - 13) & MMIO_GEN_MASK; } -- 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 04/24/2013 08:59 PM, Gleb Natapov wrote: > On Mon, Apr 01, 2013 at 05:56:49PM +0800, Xiao Guangrong wrote: >> Then it has chance to trigger mmio generation number wrap-around >> >> Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> >> --- >> arch/x86/include/asm/kvm_host.h | 1 + >> arch/x86/kvm/mmu.c | 8 ++++++++ >> virt/kvm/kvm_main.c | 6 ++++++ >> 3 files changed, 15 insertions(+), 0 deletions(-) >> >> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >> index 6c1e642..4e1f7cb 100644 >> --- a/arch/x86/include/asm/kvm_host.h >> +++ b/arch/x86/include/asm/kvm_host.h >> @@ -767,6 +767,7 @@ void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, >> struct kvm_memory_slot *slot, >> gfn_t gfn_offset, unsigned long mask); >> void kvm_mmu_zap_all(struct kvm *kvm); >> +void kvm_arch_init_generation(struct kvm *kvm); >> void kvm_mmu_invalid_mmio_sptes(struct kvm *kvm); >> unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm); >> void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages); >> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c >> index d314e21..dcc059c 100644 >> --- a/arch/x86/kvm/mmu.c >> +++ b/arch/x86/kvm/mmu.c >> @@ -4279,6 +4279,14 @@ restart: >> spin_unlock(&kvm->mmu_lock); >> } >> >> +void kvm_arch_init_generation(struct kvm *kvm) >> +{ >> + mutex_lock(&kvm->slots_lock); >> + /* It is easier to trigger mmio generation-number wrap-around. */ >> + kvm_memslots(kvm)->generation = MMIO_MAX_GEN - 13; > kvm_memslots(kvm)->generation should never overflow since > (read|write)_cached mechanism does not handle it. Initialising it to > anything but 0 makes overflow more likely. > > You can hide mmio overflow trick in kvm_current_mmio_generation(): > > static unsigned int kvm_current_mmio_generation(struct kvm *kvm) > { > return (kvm_memslots(kvm)->generation + MMIO_MAX_GEN - 13) & MMIO_GEN_MASK; > } Very smart idea. Thanks you, 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/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 6c1e642..4e1f7cb 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -767,6 +767,7 @@ void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn_offset, unsigned long mask); void kvm_mmu_zap_all(struct kvm *kvm); +void kvm_arch_init_generation(struct kvm *kvm); void kvm_mmu_invalid_mmio_sptes(struct kvm *kvm); unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm); void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages); diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index d314e21..dcc059c 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -4279,6 +4279,14 @@ restart: spin_unlock(&kvm->mmu_lock); } +void kvm_arch_init_generation(struct kvm *kvm) +{ + mutex_lock(&kvm->slots_lock); + /* It is easier to trigger mmio generation-number wrap-around. */ + kvm_memslots(kvm)->generation = MMIO_MAX_GEN - 13; + mutex_unlock(&kvm->slots_lock); +} + void kvm_mmu_invalid_mmio_sptes(struct kvm *kvm) { /* diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index ff71541..d21694a 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -459,6 +459,10 @@ static void kvm_init_memslots_id(struct kvm *kvm) slots->id_to_index[i] = slots->memslots[i].id = i; } +void __attribute__((weak)) kvm_arch_init_generation(struct kvm *kvm) +{ +} + static struct kvm *kvm_create_vm(unsigned long type) { int r, i; @@ -505,6 +509,8 @@ static struct kvm *kvm_create_vm(unsigned long type) mutex_init(&kvm->slots_lock); atomic_set(&kvm->users_count, 1); + kvm_arch_init_generation(kvm); + r = kvm_init_mmu_notifier(kvm); if (r) goto out_err;
Then it has chance to trigger mmio generation number wrap-around Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/mmu.c | 8 ++++++++ virt/kvm/kvm_main.c | 6 ++++++ 3 files changed, 15 insertions(+), 0 deletions(-)