On Fri, Mar 29, 2013 at 09:35:21AM -0700, Andrew Honig wrote:
> This patch adds support for kvm_gfn_to_hva_cache_init functions for
> reads and writes that will cross a page. If the range falls within
> the same memslot, then this will be a fast operation. If the range
> is split between two memslots, then the slower kvm_read_guest and
> kvm_write_guest are used.
>
> Tested: Test against kvm_clock unit tests.
>
> Signed-off-by: Andrew Honig <[email protected]>
Applied, thanks.
> ---
> arch/x86/kvm/lapic.c | 2 +-
> arch/x86/kvm/x86.c | 13 ++++++-------
> include/linux/kvm_host.h | 2 +-
> include/linux/kvm_types.h | 1 +
> virt/kvm/kvm_main.c | 47
> +++++++++++++++++++++++++++++++++++----------
> 5 files changed, 46 insertions(+), 19 deletions(-)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 02b51dd..f77df1c 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1857,7 +1857,7 @@ int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64
> data)
> if (!pv_eoi_enabled(vcpu))
> return 0;
> return kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.pv_eoi.data,
> - addr);
> + addr, sizeof(u8));
> }
>
> void kvm_lapic_init(void)
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index f19ac0a..e172132 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1823,7 +1823,8 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu
> *vcpu, u64 data)
> return 0;
> }
>
> - if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.apf.data, gpa))
> + if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.apf.data, gpa,
> + sizeof(u32)))
> return 1;
>
> vcpu->arch.apf.send_user_only = !(data & KVM_ASYNC_PF_SEND_ALWAYS);
> @@ -1952,12 +1953,9 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct
> msr_data *msr_info)
>
> gpa_offset = data & ~(PAGE_MASK | 1);
>
> - /* Check that the address is 32-byte aligned. */
> - if (gpa_offset & (sizeof(struct pvclock_vcpu_time_info) - 1))
> - break;
> -
> if (kvm_gfn_to_hva_cache_init(vcpu->kvm,
> - &vcpu->arch.pv_time, data & ~1ULL))
> + &vcpu->arch.pv_time, data & ~1ULL,
> + sizeof(struct pvclock_vcpu_time_info)))
> vcpu->arch.pv_time_enabled = false;
> else
> vcpu->arch.pv_time_enabled = true;
> @@ -1977,7 +1975,8 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct
> msr_data *msr_info)
> return 1;
>
> if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.st.stime,
> - data &
> KVM_STEAL_VALID_BITS))
> + data & KVM_STEAL_VALID_BITS,
> + sizeof(struct kvm_steal_time)))
> return 1;
>
> vcpu->arch.st.msr_val = data;
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index cad77fe..c139582 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -518,7 +518,7 @@ int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const
> void *data,
> int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> void *data, unsigned long len);
> int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> - gpa_t gpa);
> + gpa_t gpa, unsigned long len);
> int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len);
> int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len);
> struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);
> diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
> index fa7cc72..b0bcce0 100644
> --- a/include/linux/kvm_types.h
> +++ b/include/linux/kvm_types.h
> @@ -71,6 +71,7 @@ struct gfn_to_hva_cache {
> u64 generation;
> gpa_t gpa;
> unsigned long hva;
> + unsigned long len;
> struct kvm_memory_slot *memslot;
> };
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index adc68fe..119564f 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1541,21 +1541,38 @@ int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const
> void *data,
> }
>
> int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> - gpa_t gpa)
> + gpa_t gpa, unsigned long len)
> {
> struct kvm_memslots *slots = kvm_memslots(kvm);
> int offset = offset_in_page(gpa);
> - gfn_t gfn = gpa >> PAGE_SHIFT;
> + gfn_t start_gfn = gpa >> PAGE_SHIFT;
> + gfn_t end_gfn = (gpa + len - 1) >> PAGE_SHIFT;
> + gfn_t nr_pages_needed = end_gfn - start_gfn + 1;
> + gfn_t nr_pages_avail;
>
> ghc->gpa = gpa;
> ghc->generation = slots->generation;
> - ghc->memslot = gfn_to_memslot(kvm, gfn);
> - ghc->hva = gfn_to_hva_many(ghc->memslot, gfn, NULL);
> - if (!kvm_is_error_hva(ghc->hva))
> + ghc->len = len;
> + ghc->memslot = gfn_to_memslot(kvm, start_gfn);
> + ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn, &nr_pages_avail);
> + if (!kvm_is_error_hva(ghc->hva) && nr_pages_avail >= nr_pages_needed) {
> ghc->hva += offset;
> - else
> - return -EFAULT;
> -
> + } else {
> + /*
> + * If the requested region crosses two memslots, we still
> + * verify that the entire region is valid here.
> + */
> + while (start_gfn <= end_gfn) {
> + ghc->memslot = gfn_to_memslot(kvm, start_gfn);
> + ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn,
> + &nr_pages_avail);
> + if (kvm_is_error_hva(ghc->hva))
> + return -EFAULT;
> + start_gfn += nr_pages_avail;
> + }
> + /* Use the slow path for cross page reads and writes. */
> + ghc->memslot = NULL;
> + }
> return 0;
> }
> EXPORT_SYMBOL_GPL(kvm_gfn_to_hva_cache_init);
> @@ -1566,8 +1583,13 @@ int kvm_write_guest_cached(struct kvm *kvm, struct
> gfn_to_hva_cache *ghc,
> struct kvm_memslots *slots = kvm_memslots(kvm);
> int r;
>
> + BUG_ON(len > ghc->len);
> +
> if (slots->generation != ghc->generation)
> - kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa);
> + kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa, ghc->len);
> +
> + if (unlikely(!ghc->memslot))
> + return kvm_write_guest(kvm, ghc->gpa, data, len);
>
> if (kvm_is_error_hva(ghc->hva))
> return -EFAULT;
> @@ -1587,8 +1609,13 @@ int kvm_read_guest_cached(struct kvm *kvm, struct
> gfn_to_hva_cache *ghc,
> struct kvm_memslots *slots = kvm_memslots(kvm);
> int r;
>
> + BUG_ON(len > ghc->len);
> +
> if (slots->generation != ghc->generation)
> - kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa);
> + kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa, ghc->len);
> +
> + if (unlikely(!ghc->memslot))
> + return kvm_read_guest(kvm, ghc->gpa, data, len);
>
> if (kvm_is_error_hva(ghc->hva))
> return -EFAULT;
> --
> 1.7.10.4
>
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--
Gleb.
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