linux-kernel - Re: [PATCH 1/5] KVM: x86: Add function to inject guest page fault with reserved bits set

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Date:   Thu, 27 Feb 2020 11:30:01 -0800
From:   Ben Gardon <bgardon@...gle.com>
To:     Mohammed Gamal <mgamal@...hat.com>
Cc:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>, wanpengli@...cent.com,
        Jim Mattson <jmattson@...gle.com>, joro@...tes.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] KVM: x86: Add function to inject guest page fault
 with reserved bits set

On Thu, Feb 27, 2020 at 9:23 AM Mohammed Gamal <mgamal@...hat.com> wrote:
>
> Signed-off-by: Mohammed Gamal <mgamal@...hat.com>
> ---
>  arch/x86/kvm/x86.c | 14 ++++++++++++++
>  arch/x86/kvm/x86.h |  1 +
>  2 files changed, 15 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 359fcd395132..434c55a8b719 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -10494,6 +10494,20 @@ u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu)
>  }
>  EXPORT_SYMBOL_GPL(kvm_spec_ctrl_valid_bits);
>
> +void kvm_inject_rsvd_bits_pf(struct kvm_vcpu *vcpu, gpa_t gpa)
> +{
> +       struct x86_exception fault;
> +
> +       fault.vector = PF_VECTOR;
> +       fault.error_code_valid = true;
> +       fault.error_code = PFERR_RSVD_MASK;
> +       fault.nested_page_fault = false;
> +       fault.address = gpa;
> +
> +       kvm_inject_page_fault(vcpu, &fault);
> +}
> +EXPORT_SYMBOL_GPL(kvm_inject_rsvd_bits_pf);
> +

There are calls to kvm_mmu_page_fault in arch/x86/kvm/mmu/mmu.c that
don't get the check and injected page fault in the later patches in
this series. Is the check not needed in those cases?

>  EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
>  EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
>  EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> index 3624665acee4..7d8ab28a6983 100644
> --- a/arch/x86/kvm/x86.h
> +++ b/arch/x86/kvm/x86.h
> @@ -276,6 +276,7 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata);
>  bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn,
>                                           int page_num);
>  bool kvm_vector_hashing_enabled(void);
> +void kvm_inject_rsvd_bits_pf(struct kvm_vcpu *vcpu, gpa_t gpa);
>  int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
>                             int emulation_type, void *insn, int insn_len);
>  enum exit_fastpath_completion handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu);
> --
> 2.21.1
>