Re: [RESEND PATCH v10 05/10] x86: spp: Introduce user-space SPP IOCTLs

[Sean Christopherson]

On Thu, Jan 02, 2020 at 02:13:14PM +0800, Yang Weijiang wrote:
> User application, e.g., QEMU or VMI, must initialize SPP
> before gets/sets SPP subpages, the dynamic initialization is to
> reduce the extra storage cost if the SPP feature is not not used.
> 
> Co-developed-by: He Chen <he.chen@xxxxxxxxxxxxxxx>
> Signed-off-by: He Chen <he.chen@xxxxxxxxxxxxxxx>
> Co-developed-by: Zhang Yi <yi.z.zhang@xxxxxxxxxxxxxxx>
> Signed-off-by: Zhang Yi <yi.z.zhang@xxxxxxxxxxxxxxx>
> Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
> ---
>  arch/x86/include/asm/kvm_host.h |  4 ++
>  arch/x86/kvm/mmu/spp.c          | 44 +++++++++++++++
>  arch/x86/kvm/mmu/spp.h          |  9 ++++
>  arch/x86/kvm/vmx/vmx.c          | 15 ++++++
>  arch/x86/kvm/x86.c              | 95 ++++++++++++++++++++++++++++++++-
>  include/uapi/linux/kvm.h        |  3 ++
>  6 files changed, 169 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index f5145b86d620..c7a9f03f39a7 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1238,6 +1238,10 @@ struct kvm_x86_ops {
>  
>  	bool (*apic_init_signal_blocked)(struct kvm_vcpu *vcpu);
>  	int (*enable_direct_tlbflush)(struct kvm_vcpu *vcpu);
> +
> +	int (*init_spp)(struct kvm *kvm);
> +	int (*flush_subpages)(struct kvm *kvm, u64 gfn, u32 npages);
> +	int (*get_inst_len)(struct kvm_vcpu *vcpu);

If this is necessary, which hopefully it isn't, then get_insn_len() to be
consistent with other KVM nomenclature.

A comment for the series overall, it needs a lot of work to properly order
code between patches.  E.g. this patch introduces get_inst_len() without
any justification in the changelog and without a user.  At best it's
confusing, at worst this series will be impossible to bisect.