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    Subject[PATCH v3 2/6] KVM: MMU: store generation-number into mmio spte
    Date
    Store the generation-number into bit3 ~ bit11 and bit52 ~ bit61, totally
    19 bits can be used, it should be enough for nearly all most common cases

    In this patch, the generation-number is always 0, it will be changed in
    the later patch

    Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
    ---
    arch/x86/kvm/mmu.c | 58 ++++++++++++++++++++++++++++++++++++++--------
    arch/x86/kvm/mmutrace.h | 10 ++++----
    arch/x86/kvm/paging_tmpl.h | 3 ++-
    3 files changed, 56 insertions(+), 15 deletions(-)

    diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
    index 6941fa7..eca91bd 100644
    --- a/arch/x86/kvm/mmu.c
    +++ b/arch/x86/kvm/mmu.c
    @@ -197,15 +197,52 @@ void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask)
    }
    EXPORT_SYMBOL_GPL(kvm_mmu_set_mmio_spte_mask);

    -static void mark_mmio_spte(u64 *sptep, u64 gfn, unsigned access)
    +/*
    + * spte bits of bit 3 ~ bit 11 are used as low 9 bits of generation number,
    + * the bits of bits 52 ~ bit 61 are used as high 10 bits of generation
    + * number.
    + */
    +#define MMIO_SPTE_GEN_LOW_SHIFT 3
    +#define MMIO_SPTE_GEN_HIGH_SHIFT 52
    +
    +#define MMIO_GEN_LOW_SHIFT 9
    +#define MMIO_GEN_LOW_MASK ((1 << MMIO_GEN_LOW_SHIFT) - 1)
    +#define MMIO_MAX_GEN ((1 << 19) - 1)
    +
    +static u64 generation_mmio_spte_mask(unsigned int gen)
    +{
    + u64 mask;
    +
    + WARN_ON(gen > MMIO_MAX_GEN);
    +
    + mask = (gen & MMIO_GEN_LOW_MASK) << MMIO_SPTE_GEN_LOW_SHIFT;
    + mask |= ((u64)gen >> MMIO_GEN_LOW_SHIFT) << MMIO_SPTE_GEN_HIGH_SHIFT;
    + return mask;
    +}
    +
    +static unsigned int get_mmio_spte_generation(u64 spte)
    +{
    + unsigned int gen;
    +
    + spte &= ~shadow_mmio_mask;
    +
    + gen = (spte >> MMIO_SPTE_GEN_LOW_SHIFT) & MMIO_GEN_LOW_MASK;
    + gen |= (spte >> MMIO_SPTE_GEN_HIGH_SHIFT) << MMIO_GEN_LOW_SHIFT;
    + return gen;
    +}
    +
    +static void mark_mmio_spte(struct kvm *kvm, u64 *sptep, u64 gfn,
    + unsigned access)
    {
    struct kvm_mmu_page *sp = page_header(__pa(sptep));
    + u64 mask = generation_mmio_spte_mask(0);

    access &= ACC_WRITE_MASK | ACC_USER_MASK;
    -
    + mask |= shadow_mmio_mask | access | gfn << PAGE_SHIFT;
    sp->mmio_cached = true;
    - trace_mark_mmio_spte(sptep, gfn, access);
    - mmu_spte_set(sptep, shadow_mmio_mask | access | gfn << PAGE_SHIFT);
    +
    + trace_mark_mmio_spte(sptep, gfn, access, 0);
    + mmu_spte_set(sptep, mask);
    }

    static bool is_mmio_spte(u64 spte)
    @@ -223,10 +260,11 @@ static unsigned get_mmio_spte_access(u64 spte)
    return (spte & ~shadow_mmio_mask) & ~PAGE_MASK;
    }

    -static bool set_mmio_spte(u64 *sptep, gfn_t gfn, pfn_t pfn, unsigned access)
    +static bool set_mmio_spte(struct kvm *kvm, u64 *sptep, gfn_t gfn,
    + pfn_t pfn, unsigned access)
    {
    if (unlikely(is_noslot_pfn(pfn))) {
    - mark_mmio_spte(sptep, gfn, access);
    + mark_mmio_spte(kvm, sptep, gfn, access);
    return true;
    }

    @@ -2364,7 +2402,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
    u64 spte;
    int ret = 0;

    - if (set_mmio_spte(sptep, gfn, pfn, pte_access))
    + if (set_mmio_spte(vcpu->kvm, sptep, gfn, pfn, pte_access))
    return 0;

    spte = PT_PRESENT_MASK;
    @@ -3427,8 +3465,8 @@ static inline void protect_clean_gpte(unsigned *access, unsigned gpte)
    *access &= mask;
    }

    -static bool sync_mmio_spte(u64 *sptep, gfn_t gfn, unsigned access,
    - int *nr_present)
    +static bool sync_mmio_spte(struct kvm *kvm, u64 *sptep, gfn_t gfn,
    + unsigned access, int *nr_present)
    {
    if (unlikely(is_mmio_spte(*sptep))) {
    if (gfn != get_mmio_spte_gfn(*sptep)) {
    @@ -3437,7 +3475,7 @@ static bool sync_mmio_spte(u64 *sptep, gfn_t gfn, unsigned access,
    }

    (*nr_present)++;
    - mark_mmio_spte(sptep, gfn, access);
    + mark_mmio_spte(kvm, sptep, gfn, access);
    return true;
    }

    diff --git a/arch/x86/kvm/mmutrace.h b/arch/x86/kvm/mmutrace.h
    index eb444dd..ad24757 100644
    --- a/arch/x86/kvm/mmutrace.h
    +++ b/arch/x86/kvm/mmutrace.h
    @@ -199,23 +199,25 @@ DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_prepare_zap_page,

    TRACE_EVENT(
    mark_mmio_spte,
    - TP_PROTO(u64 *sptep, gfn_t gfn, unsigned access),
    - TP_ARGS(sptep, gfn, access),
    + TP_PROTO(u64 *sptep, gfn_t gfn, unsigned access, unsigned int gen),
    + TP_ARGS(sptep, gfn, access, gen),

    TP_STRUCT__entry(
    __field(void *, sptep)
    __field(gfn_t, gfn)
    __field(unsigned, access)
    + __field(unsigned int, gen)
    ),

    TP_fast_assign(
    __entry->sptep = sptep;
    __entry->gfn = gfn;
    __entry->access = access;
    + __entry->gen = gen;
    ),

    - TP_printk("sptep:%p gfn %llx access %x", __entry->sptep, __entry->gfn,
    - __entry->access)
    + TP_printk("sptep:%p gfn %llx access %x gen %x", __entry->sptep,
    + __entry->gfn, __entry->access, __entry->gen)
    );

    TRACE_EVENT(
    diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
    index da20860..fb50fa6 100644
    --- a/arch/x86/kvm/paging_tmpl.h
    +++ b/arch/x86/kvm/paging_tmpl.h
    @@ -792,7 +792,8 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
    pte_access &= gpte_access(vcpu, gpte);
    protect_clean_gpte(&pte_access, gpte);

    - if (sync_mmio_spte(&sp->spt[i], gfn, pte_access, &nr_present))
    + if (sync_mmio_spte(vcpu->kvm, &sp->spt[i], gfn, pte_access,
    + &nr_present))
    continue;

    if (gfn != sp->gfns[i]) {
    --
    1.8.1.4


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