Re: [PATCH v2 4/8] KVM: x86: Add a helper to get the sparse VP_SET for IPIs and TLB flushes

Vitaly Kuznetsov
2021-11-01T10:06:37Z

Sean Christopherson <seanjc@google.com> writes:

> Add a helper, kvm_get_sparse_vp_set(), to handle sanity checks related to
> the VARHEAD field and reading the sparse banks of a VP_SET. A future
> commit to reduce the memory footprint of sparse_banks will introduce more
> common code to the sparse bank retrieval.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kvm/hyperv.c | 32 ++++++++++++++++----------------
> 1 file changed, 16 insertions(+), 16 deletions(-)
>
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index e68931ed27f6..3d0981163eed 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -1750,10 +1750,19 @@ struct kvm_hv_hcall {
> sse128_t xmm[HV_HYPERCALL_MAX_XMM_REGISTERS];
> };
>
> +static u64 kvm_get_sparse_vp_set(struct kvm *kvm, struct kvm_hv_hcall *hc,
> + u64 *sparse_banks, gpa_t offset)
> +{
> + if (hc->var_cnt > 64)
> + return -EINVAL;
> +
> + return kvm_read_guest(kvm, hc->ingpa + offset, sparse_banks,
> + hc->var_cnt * sizeof(*sparse_banks));
> +}
> +
> static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool ex)
> {
> int i;
> - gpa_t gpa;
> struct kvm *kvm = vcpu->kvm;
> struct hv_tlb_flush_ex flush_ex;
> struct hv_tlb_flush flush;
> @@ -1830,13 +1839,9 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
> goto do_flush;
> }
>
> - if (hc->var_cnt > 64)
> - return HV_STATUS_INVALID_HYPERCALL_INPUT;
> -
> - gpa = hc->ingpa + offsetof(struct hv_tlb_flush_ex,
> - hv_vp_set.bank_contents);
> - if (unlikely(kvm_read_guest(kvm, gpa, sparse_banks,
> - hc->var_cnt * sizeof(sparse_banks[0]))))
> + if (kvm_get_sparse_vp_set(kvm, hc, sparse_banks,
> + offsetof(struct hv_tlb_flush_ex,
> + hv_vp_set.bank_contents)))
> return HV_STATUS_INVALID_HYPERCALL_INPUT;
> }
>
> @@ -1933,14 +1938,9 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
> if (!hc->var_cnt)
> goto ret_success;
>
> - if (hc->var_cnt > 64)
> - return HV_STATUS_INVALID_HYPERCALL_INPUT;
> -
> - if (kvm_read_guest(kvm,
> - hc->ingpa + offsetof(struct hv_send_ipi_ex,
> - vp_set.bank_contents),
> - sparse_banks,
> - hc->var_cnt * sizeof(sparse_banks[0])))
> + if (kvm_get_sparse_vp_set(kvm, hc, sparse_banks,
> + offsetof(struct hv_send_ipi_ex,
> + vp_set.bank_contents)))
> return HV_STATUS_INVALID_HYPERCALL_INPUT;
> }

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

--
Vitaly