Re: [PATCH 09/11] KVM: MMU: use page track for non-leaf shadow pages

Paolo Bonzini
2016-02-29T15:22:21Z

On 24/02/2016 10:51, Xiao Guangrong wrote:
> non-leaf shadow pages are always write protected, it can be the user
> of page track
>
> Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
> ---
> arch/x86/kvm/mmu.c | 26 +++++++++++++++++++++-----
> 1 file changed, 21 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 58c067d..74684b2 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -806,11 +806,17 @@ static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
> struct kvm_memory_slot *slot;
> gfn_t gfn;
>
> + kvm->arch.indirect_shadow_pages++;
> gfn = sp->gfn;
> slots = kvm_memslots_for_spte_role(kvm, sp->role);
> slot = __gfn_to_memslot(slots, gfn);
> +
> + /* the non-leaf shadow pages are keeping readonly. */
> + if (sp->role.level > PT_PAGE_TABLE_LEVEL)
> + return kvm_slot_page_track_add_page(kvm, slot, gfn,
> + KVM_PAGE_TRACK_WRITE);
> +
> kvm_mmu_gfn_disallow_lpage(slot, gfn);
> - kvm->arch.indirect_shadow_pages++;
> }
>
> static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
> @@ -819,11 +825,15 @@ static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
> struct kvm_memory_slot *slot;
> gfn_t gfn;
>
> + kvm->arch.indirect_shadow_pages--;
> gfn = sp->gfn;
> slots = kvm_memslots_for_spte_role(kvm, sp->role);
> slot = __gfn_to_memslot(slots, gfn);
> + if (sp->role.level > PT_PAGE_TABLE_LEVEL)
> + return kvm_slot_page_track_remove_page(kvm, slot, gfn,
> + KVM_PAGE_TRACK_WRITE);
> +
> kvm_mmu_gfn_allow_lpage(slot, gfn);
> - kvm->arch.indirect_shadow_pages--;
> }
>
> static bool __mmu_gfn_lpage_is_disallowed(gfn_t gfn, int level,
> @@ -2132,12 +2142,18 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
> hlist_add_head(&sp->hash_link,
> &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)]);
> if (!direct) {
> - if (rmap_write_protect(vcpu, gfn))
> + /*
> + * we should do write protection before syncing pages
> + * otherwise the content of the synced shadow page may
> + * be inconsistent with guest page table.
> + */
> + account_shadowed(vcpu->kvm, sp);
> +
> + if (level == PT_PAGE_TABLE_LEVEL &&
> + rmap_write_protect(vcpu, gfn))
> kvm_flush_remote_tlbs(vcpu->kvm);
> if (level > PT_PAGE_TABLE_LEVEL && need_sync)
> kvm_sync_pages(vcpu, gfn);
> -
> - account_shadowed(vcpu->kvm, sp);
> }
> sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen;
> clear_page(sp->spt);
>

Hi,

I'm applying this series with just a very simple change on top of this patch:

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 74684b2b7e69..fe03d2a1d4d3 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2148,10 +2148,10 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
* be inconsistent with guest page table.
*/
account_shadowed(vcpu->kvm, sp);
-
if (level == PT_PAGE_TABLE_LEVEL &&
rmap_write_protect(vcpu, gfn))
kvm_flush_remote_tlbs(vcpu->kvm);
+
if (level > PT_PAGE_TABLE_LEVEL && need_sync)
kvm_sync_pages(vcpu, gfn);
}

Yes, it's just moving around an empty line. :)

Paolo