On Thu, 6 Feb 2020 15:50:18 +0100
Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx> wrote:
> - Use document title and chapter markups;
> - Add markups for literal blocks;
> - use :field: for field descriptions;
> - Add blank lines and adjust indentation.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
> ---
> Documentation/virt/kvm/index.rst | 1 +
> .../virt/kvm/{locking.txt => locking.rst} | 111 ++++++++++--------
> 2 files changed, 63 insertions(+), 49 deletions(-)
> rename Documentation/virt/kvm/{locking.txt => locking.rst} (78%)
(...)
> @@ -48,19 +52,23 @@ restore the saved R/X bits if VMX_EPT_TRACK_ACCESS mask is set, or both. This
> is safe because whenever changing these bits can be detected by cmpxchg.
>
> But we need carefully check these cases:
> -1): The mapping from gfn to pfn
> +
> +1) The mapping from gfn to pfn
> +
> The mapping from gfn to pfn may be changed since we can only ensure the pfn
> is not changed during cmpxchg. This is a ABA problem, for example, below case
> will happen:
>
> -At the beginning:
> -gpte = gfn1
> -gfn1 is mapped to pfn1 on host
> -spte is the shadow page table entry corresponding with gpte and
> -spte = pfn1
> +At the beginning::
>
> - VCPU 0 VCPU0
> -on fast page fault path:
> + gpte = gfn1
> + gfn1 is mapped to pfn1 on host
> + spte is the shadow page table entry corresponding with gpte and
> + spte = pfn1
> +
> + VCPU 0 VCPU0
> +
> +on fast page fault path::
>
> old_spte = *spte;
> pfn1 is swapped out:
I'm wondering if that should rather be converted to a proper table.
(...)
> @@ -99,12 +109,14 @@ Accessed bit and Dirty bit can not be lost.
> But it is not true after fast page fault since the spte can be marked
> writable between reading spte and updating spte. Like below case:
>
> -At the beginning:
> -spte.W = 0
> -spte.Accessed = 1
> +At the beginning::
>
> - VCPU 0 VCPU0
> -In mmu_spte_clear_track_bits():
> + spte.W = 0
> + spte.Accessed = 1
> +
> + VCPU 0 VCPU0
> +
> +In mmu_spte_clear_track_bits()::
>
> old_spte = *spte;
>
This one as well.
