Re: [PATCH RFC v7 04/64] KVM: x86: Add 'fault_is_private' x86 op

[Borislav Petkov]

On Wed, Dec 14, 2022 at 01:39:56PM -0600, Michael Roth wrote:
> This callback is used by the KVM MMU to check whether a #NPF was
> or a private GPA or not.

s/or //

> 
> Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
> ---
>  arch/x86/include/asm/kvm-x86-ops.h |  1 +
>  arch/x86/include/asm/kvm_host.h    |  1 +
>  arch/x86/kvm/mmu/mmu.c             |  3 +--
>  arch/x86/kvm/mmu/mmu_internal.h    | 40 +++++++++++++++++++++++++++---
>  4 files changed, 39 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
> index f530a550c092..efae987cdce0 100644
> --- a/arch/x86/include/asm/kvm-x86-ops.h
> +++ b/arch/x86/include/asm/kvm-x86-ops.h
> @@ -132,6 +132,7 @@ KVM_X86_OP(complete_emulated_msr)
>  KVM_X86_OP(vcpu_deliver_sipi_vector)
>  KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons);
>  KVM_X86_OP_OPTIONAL_RET0(private_mem_enabled);
> +KVM_X86_OP_OPTIONAL_RET0(fault_is_private);
>  
>  #undef KVM_X86_OP
>  #undef KVM_X86_OP_OPTIONAL
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 9317abffbf68..92539708f062 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1636,6 +1636,7 @@ struct kvm_x86_ops {
>  	void (*load_mmu_pgd)(struct kvm_vcpu *vcpu, hpa_t root_hpa,
>  			     int root_level);
>  	int (*private_mem_enabled)(struct kvm *kvm);
> +	int (*fault_is_private)(struct kvm *kvm, gpa_t gpa, u64 error_code, bool *private_fault);

bool

and then you don't need the silly "== 1" at the call site.

>  
>  	bool (*has_wbinvd_exit)(void);

...

> @@ -261,13 +293,13 @@ enum {
>  };
>  
>  static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
> -					u32 err, bool prefetch)
> +					u64 err, bool prefetch)

The u32 -> u64 change of err could use a sentence or two of
clarification in the commit message...

>  {
>  	bool is_tdp = likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault);
>  
>  	struct kvm_page_fault fault = {
>  		.addr = cr2_or_gpa,
> -		.error_code = err,
> +		.error_code = lower_32_bits(err),
>  		.exec = err & PFERR_FETCH_MASK,
>  		.write = err & PFERR_WRITE_MASK,
>  		.present = err & PFERR_PRESENT_MASK,
> @@ -281,8 +313,8 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
>  		.max_level = KVM_MAX_HUGEPAGE_LEVEL,
>  		.req_level = PG_LEVEL_4K,
>  		.goal_level = PG_LEVEL_4K,
> -		.is_private = IS_ENABLED(CONFIG_HAVE_KVM_PRIVATE_MEM_TESTING) && is_tdp &&
> -				kvm_mem_is_private(vcpu->kvm, cr2_or_gpa >> PAGE_SHIFT),
> +		.is_private = is_tdp && kvm_mmu_fault_is_private(vcpu->kvm,
> +								 cr2_or_gpa, err),
>  	};
>  	int r;
>  
> -- 
> 2.25.1
> 

-- 
Regards/Gruss,
    Boris.

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