linux-kernel - Re: [PATCH v18 055/121] KVM: VMX: Move setting of EPT MMU masks to common VT-x code

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Date: Sun, 4 Feb 2024 17:21:12 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: isaku.yamahata@...el.com
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 isaku.yamahata@...il.com, Paolo Bonzini <pbonzini@...hat.com>,
 erdemaktas@...gle.com, Sean Christopherson <seanjc@...gle.com>,
 Sagi Shahar <sagis@...gle.com>, Kai Huang <kai.huang@...el.com>,
 chen.bo@...el.com, hang.yuan@...el.com, tina.zhang@...el.com,
 Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH v18 055/121] KVM: VMX: Move setting of EPT MMU masks to
 common VT-x code



On 1/23/2024 7:53 AM, isaku.yamahata@...el.com wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.com>
>
> EPT MMU masks are used commonly for VMX and TDX.  The value needs to be
> initialized in common code before both VMX/TDX-specific initialization
> code.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> ---
>   arch/x86/kvm/vmx/main.c | 9 +++++++++
>   arch/x86/kvm/vmx/vmx.c  | 4 ----
>   2 files changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> index de4b6f924a36..8059b44ed159 100644
> --- a/arch/x86/kvm/vmx/main.c
> +++ b/arch/x86/kvm/vmx/main.c
> @@ -4,6 +4,7 @@
>   #include "x86_ops.h"
>   #include "vmx.h"
>   #include "nested.h"
> +#include "mmu.h"
>   #include "pmu.h"
>   #include "tdx.h"
>   #include "tdx_arch.h"
> @@ -54,6 +55,14 @@ static __init int vt_hardware_setup(void)
>   	if (ret)
>   		return ret;
>   
> +	/*
> +	 * As kvm_mmu_set_ept_masks() updates enable_mmio_caching, call it
> +	 * before checking enable_mmio_caching.
> +	 */
> +	if (enable_ept)
> +		kvm_mmu_set_ept_masks(enable_ept_ad_bits,
> +				      cpu_has_vmx_ept_execute_only());
> +
>   	enable_tdx = enable_tdx && !tdx_hardware_setup(&vt_x86_ops);
>   
>   	return 0;
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 185e22a2e101..c2da39ceb02b 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -8452,10 +8452,6 @@ __init int vmx_hardware_setup(void)
>   
>   	set_bit(0, vmx_vpid_bitmap); /* 0 is reserved for host */
>   
> -	if (enable_ept)
> -		kvm_mmu_set_ept_masks(enable_ept_ad_bits,
> -				      cpu_has_vmx_ept_execute_only());
> -

 From hardware_setup aspect, vmx_hardware_setup() is the dependency of
tdx_hardware_setup() and vmx_hardware_setup() is called earlier than
tdx_hardware_setup(), it seems no need to move the code.


>   	/*
>   	 * Setup shadow_me_value/shadow_me_mask to include MKTME KeyID
>   	 * bits to shadow_zero_check.