linux-kernel - Re: [PATCH 08/14] KVM: x86/mmu: Make dirty log size hook (PML) a value, not a function

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Date:   Thu, 18 Feb 2021 13:45:37 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Ben Gardon <bgardon@...gle.com>,
        Makarand Sonare <makarandsonare@...gle.com>
Subject: Re: [PATCH 08/14] KVM: x86/mmu: Make dirty log size hook (PML) a
 value, not a function

On 13/02/21 01:50, Sean Christopherson wrote:
> Store the vendor-specific dirty log size in a variable, there's no need
> to wrap it in a function since the value is constant after
> hardware_setup() runs.

For now... :)

Paolo

> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>   arch/x86/include/asm/kvm-x86-ops.h | 1 -
>   arch/x86/include/asm/kvm_host.h    | 2 +-
>   arch/x86/kvm/mmu/mmu.c             | 5 +----
>   arch/x86/kvm/vmx/vmx.c             | 9 ++-------
>   4 files changed, 4 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
> index 355a2ab8fc09..28c07cc01474 100644
> --- a/arch/x86/include/asm/kvm-x86-ops.h
> +++ b/arch/x86/include/asm/kvm-x86-ops.h
> @@ -97,7 +97,6 @@ KVM_X86_OP_NULL(slot_enable_log_dirty)
>   KVM_X86_OP_NULL(slot_disable_log_dirty)
>   KVM_X86_OP_NULL(flush_log_dirty)
>   KVM_X86_OP_NULL(enable_log_dirty_pt_masked)
> -KVM_X86_OP_NULL(cpu_dirty_log_size)
>   KVM_X86_OP_NULL(pre_block)
>   KVM_X86_OP_NULL(post_block)
>   KVM_X86_OP_NULL(vcpu_blocking)
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 84499aad01a4..fb59933610d9 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1294,7 +1294,7 @@ struct kvm_x86_ops {
>   	void (*enable_log_dirty_pt_masked)(struct kvm *kvm,
>   					   struct kvm_memory_slot *slot,
>   					   gfn_t offset, unsigned long mask);
> -	int (*cpu_dirty_log_size)(void);
> +	int cpu_dirty_log_size;
>   
>   	/* pmu operations of sub-arch */
>   	const struct kvm_pmu_ops *pmu_ops;
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index d5849a0e3de1..6c32e8e0f720 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -1294,10 +1294,7 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
>   
>   int kvm_cpu_dirty_log_size(void)
>   {
> -	if (kvm_x86_ops.cpu_dirty_log_size)
> -		return static_call(kvm_x86_cpu_dirty_log_size)();
> -
> -	return 0;
> +	return kvm_x86_ops.cpu_dirty_log_size;
>   }
>   
>   bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index b47ed3f412ef..f843707dd7df 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7650,11 +7650,6 @@ static bool vmx_check_apicv_inhibit_reasons(ulong bit)
>   	return supported & BIT(bit);
>   }
>   
> -static int vmx_cpu_dirty_log_size(void)
> -{
> -	return enable_pml ? PML_ENTITY_NUM : 0;
> -}
> -
>   static struct kvm_x86_ops vmx_x86_ops __initdata = {
>   	.hardware_unsetup = hardware_unsetup,
>   
> @@ -7758,6 +7753,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
>   	.slot_disable_log_dirty = vmx_slot_disable_log_dirty,
>   	.flush_log_dirty = vmx_flush_log_dirty,
>   	.enable_log_dirty_pt_masked = vmx_enable_log_dirty_pt_masked,
> +	.cpu_dirty_log_size = PML_ENTITY_NUM,
>   
>   	.pre_block = vmx_pre_block,
>   	.post_block = vmx_post_block,
> @@ -7785,7 +7781,6 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
>   
>   	.msr_filter_changed = vmx_msr_filter_changed,
>   	.complete_emulated_msr = kvm_complete_insn_gp,
> -	.cpu_dirty_log_size = vmx_cpu_dirty_log_size,
>   
>   	.vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,
>   };
> @@ -7907,7 +7902,7 @@ static __init int hardware_setup(void)
>   		vmx_x86_ops.slot_disable_log_dirty = NULL;
>   		vmx_x86_ops.flush_log_dirty = NULL;
>   		vmx_x86_ops.enable_log_dirty_pt_masked = NULL;
> -		vmx_x86_ops.cpu_dirty_log_size = NULL;
> +		vmx_x86_ops.cpu_dirty_log_size = 0;
>   	}
>   
>   	if (!cpu_has_vmx_preemption_timer())
>