Re: [PATCH 11/15] KVM: x86/MMU: Refactor vmx_get_mt_mask

[Paolo Bonzini]

On 11/16/21 00:45, Ben Gardon wrote:
> Remove the gotos from vmx_get_mt_mask to make it easier to separate out
> the parts which do not depend on vcpu state.
>
> No functional change intended.
>
>
> Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx>

Queued, thanks (with a slightly edited commit message; the patch is a 
simplification anyway).

Paolo

> ---
>   arch/x86/kvm/vmx/vmx.c | 23 +++++++----------------
>   1 file changed, 7 insertions(+), 16 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 71f54d85f104..77f45c005f28 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6987,7 +6987,6 @@ static int __init vmx_check_processor_compat(void)
>   static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
>   {
>   	u8 cache;
> -	u64 ipat = 0;
>   
>   	/* We wanted to honor guest CD/MTRR/PAT, but doing so could result in
>   	 * memory aliases with conflicting memory types and sometimes MCEs.
> @@ -7007,30 +7006,22 @@ static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
>   	 * EPT memory type is used to emulate guest CD/MTRR.
>   	 */
>   
> -	if (is_mmio) {
> -		cache = MTRR_TYPE_UNCACHABLE;
> -		goto exit;
> -	}
> +	if (is_mmio)
> +		return MTRR_TYPE_UNCACHABLE << VMX_EPT_MT_EPTE_SHIFT;
>   
> -	if (!kvm_arch_has_noncoherent_dma(vcpu->kvm)) {
> -		ipat = VMX_EPT_IPAT_BIT;
> -		cache = MTRR_TYPE_WRBACK;
> -		goto exit;
> -	}
> +	if (!kvm_arch_has_noncoherent_dma(vcpu->kvm))
> +		return (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT) | VMX_EPT_IPAT_BIT;
>   
>   	if (kvm_read_cr0(vcpu) & X86_CR0_CD) {
> -		ipat = VMX_EPT_IPAT_BIT;
>   		if (kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED))
>   			cache = MTRR_TYPE_WRBACK;
>   		else
>   			cache = MTRR_TYPE_UNCACHABLE;
> -		goto exit;
> -	}
>   
> -	cache = kvm_mtrr_get_guest_memory_type(vcpu, gfn);
> +		return (cache << VMX_EPT_MT_EPTE_SHIFT) | VMX_EPT_IPAT_BIT;
> +	}
>   
> -exit:
> -	return (cache << VMX_EPT_MT_EPTE_SHIFT) | ipat;
> +	return kvm_mtrr_get_guest_memory_type(vcpu, gfn) << VMX_EPT_MT_EPTE_SHIFT;
>   }
>   
>   static void vmcs_set_secondary_exec_control(struct vcpu_vmx *vmx, u32 new_ctl)