On 09/12/2014 00:12, Mario Smarduch wrote:
> Hi Paolo,
> I took a closer look at Christoffers comment,
> the _log description in x86.c is a repeat of the
> _protect description in kvm_main.c.
>
> I'm wondering if description below would be acceptable, or
> perhaps you had a reason leaving it as is.
Yes, it's okay.
> For the ARM variant I would word same. Please advise.
>
> Thanks.
>
> "
> /**
> * kvm_vm_ioctl_get_dirty_log - get and clear the log of dirty pages in
> a slot
> * @kvm: kvm instance
> * @log: slot id and address to which we copy the log
> *
> * Steps 1-4 below provide general overview of dirty page logging. See
> * kvm_get_dirty_log_protect() function description for additional details.
> *
> * We call kvm_get_dirty_log_protect() to handle steps 1-3, upon return we
> * always flush the TLB (step 4) even if 'protect' failed and dirty bitmap
even if a previous step failed and the dirty bitmap may be corrupt.
> * may be corrupt. Regardless of previous outcome KVM logging API does not
... the KVM logging API ...
> * preclude user space subsequent dirty log read. Flushing TLB insures
s/insures/ensures/
Paolo
> writes
> * will be marked dirty for next log read.
> *
> * 1. Take a snapshot of the bit and clear it if needed.
> * 2. Write protect the corresponding page.
> * 3. Copy the snapshot to the userspace.
> * 4. Flush TLB's if needed.
> */
> "
>
> On 11/22/2014 11:19 AM, Christoffer Dall wrote:
>> On Thu, Nov 13, 2014 at 05:57:44PM -0800, Mario Smarduch wrote:
>>> From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>>>
>>> We now have a generic function that does most of the work of
>>> kvm_vm_ioctl_get_dirty_log, now use it.
>>>
>>> Signed-off-by: Mario Smarduch <m.smarduch@xxxxxxxxxxx>
>>> ---
>>> arch/x86/include/asm/kvm_host.h | 3 --
>>> arch/x86/kvm/Kconfig | 1 +
>>> arch/x86/kvm/mmu.c | 4 +--
>>> arch/x86/kvm/x86.c | 64 ++++++---------------------------------
>>> 4 files changed, 12 insertions(+), 60 deletions(-)
>>>
>>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>>> index 7c492ed..934dc24 100644
>>> --- a/arch/x86/include/asm/kvm_host.h
>>> +++ b/arch/x86/include/asm/kvm_host.h
>>> @@ -805,9 +805,6 @@ void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask,
>>>
>>> void kvm_mmu_reset_context(struct kvm_vcpu *vcpu);
>>> void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot);
>>> -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_mmu_invalidate_mmio_sptes(struct kvm *kvm);
>>> unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm);
>>> diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
>>> index f9d16ff..d073594 100644
>>> --- a/arch/x86/kvm/Kconfig
>>> +++ b/arch/x86/kvm/Kconfig
>>> @@ -39,6 +39,7 @@ config KVM
>>> select PERF_EVENTS
>>> select HAVE_KVM_MSI
>>> select HAVE_KVM_CPU_RELAX_INTERCEPT
>>> + select KVM_GENERIC_DIRTYLOG_READ_PROTECT
>>> select KVM_VFIO
>>> ---help---
>>> Support hosting fully virtualized guest machines using hardware
>>> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>>> index 9314678..bf6b82c 100644
>>> --- a/arch/x86/kvm/mmu.c
>>> +++ b/arch/x86/kvm/mmu.c
>>> @@ -1224,7 +1224,7 @@ static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp,
>>> }
>>>
>>> /**
>>> - * kvm_mmu_write_protect_pt_masked - write protect selected PT level pages
>>> + * kvm_arch_mmu_write_protect_pt_masked - write protect selected PT level pages
>>> * @kvm: kvm instance
>>> * @slot: slot to protect
>>> * @gfn_offset: start of the BITS_PER_LONG pages we care about
>>> @@ -1233,7 +1233,7 @@ static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp,
>>> * Used when we do not need to care about huge page mappings: e.g. during dirty
>>> * logging we do not have any such mappings.
>>> */
>>> -void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
>>> +void kvm_arch_mmu_write_protect_pt_masked(struct kvm *kvm,
>>> struct kvm_memory_slot *slot,
>>> gfn_t gfn_offset, unsigned long mask)
>>> {
>>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>>> index 8f1e22d..9f8ae9a 100644
>>> --- a/arch/x86/kvm/x86.c
>>> +++ b/arch/x86/kvm/x86.c
>>> @@ -3606,77 +3606,31 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
>>> *
>>> * 1. Take a snapshot of the bit and clear it if needed.
>>> * 2. Write protect the corresponding page.
>>> - * 3. Flush TLB's if needed.
>>> - * 4. Copy the snapshot to the userspace.
>>> + * 3. Copy the snapshot to the userspace.
>>> + * 4. Flush TLB's if needed.
>>> *
>>> - * Between 2 and 3, the guest may write to the page using the remaining TLB
>>> - * entry. This is not a problem because the page will be reported dirty at
>>> - * step 4 using the snapshot taken before and step 3 ensures that successive
>>> - * writes will be logged for the next call.
>>> + * Between 2 and 4, the guest may write to the page using the remaining TLB
>>> + * entry. This is not a problem because the page is reported dirty using
>>> + * the snapshot taken before and step 4 ensures that writes done after
>>> + * exiting to userspace will be logged for the next call.
>>> */
>>
>> this seems to duplicate the comment in virt/kvm/kvm_main.c, but
>> whatever.
>>
>> FWIW:
>> Acked-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
>>
>
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