linux-kernel - Re: [PATCH v5 08/14] x86/mm: Add generic guest initialization hook

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Message-ID: <afc3e286-5a2d-62e8-e55e-b95ebe4373f4@amd.com>
Date:   Mon, 30 Oct 2023 14:19:38 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Nikunj A Dadhania <nikunj@....com>, linux-kernel@...r.kernel.org,
        x86@...nel.org, kvm@...r.kernel.org
Cc:     bp@...en8.de, mingo@...hat.com, tglx@...utronix.de,
        dave.hansen@...ux.intel.com, dionnaglaze@...gle.com,
        pgonda@...gle.com, seanjc@...gle.com, pbonzini@...hat.com
Subject: Re: [PATCH v5 08/14] x86/mm: Add generic guest initialization hook

On 10/30/23 01:36, Nikunj A Dadhania wrote:
> Add generic enc_init guest hook for performing any type of
> initialization that is vendor specific.

I think this commit message should be expanded on a bit... like when it is 
intended to be called, etc.

Thanks,
Tom

> 
> Signed-off-by: Nikunj A Dadhania <nikunj@....com>
> ---
>   arch/x86/include/asm/x86_init.h | 2 ++
>   arch/x86/kernel/x86_init.c      | 2 ++
>   arch/x86/mm/mem_encrypt.c       | 3 +++
>   3 files changed, 7 insertions(+)
> 
> diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
> index 5240d88db52a..6a08dcd1f3c4 100644
> --- a/arch/x86/include/asm/x86_init.h
> +++ b/arch/x86/include/asm/x86_init.h
> @@ -148,12 +148,14 @@ struct x86_init_acpi {
>    * @enc_status_change_finish	Notify HV after the encryption status of a range is changed
>    * @enc_tlb_flush_required	Returns true if a TLB flush is needed before changing page encryption status
>    * @enc_cache_flush_required	Returns true if a cache flush is needed before changing page encryption status
> + * @enc_init			Prepare and initialize encryption features
>    */
>   struct x86_guest {
>   	bool (*enc_status_change_prepare)(unsigned long vaddr, int npages, bool enc);
>   	bool (*enc_status_change_finish)(unsigned long vaddr, int npages, bool enc);
>   	bool (*enc_tlb_flush_required)(bool enc);
>   	bool (*enc_cache_flush_required)(void);
> +	void (*enc_init)(void);
>   };
>   
>   /**
> diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
> index a37ebd3b4773..a07985a96ca5 100644
> --- a/arch/x86/kernel/x86_init.c
> +++ b/arch/x86/kernel/x86_init.c
> @@ -136,6 +136,7 @@ static bool enc_status_change_finish_noop(unsigned long vaddr, int npages, bool
>   static bool enc_tlb_flush_required_noop(bool enc) { return false; }
>   static bool enc_cache_flush_required_noop(void) { return false; }
>   static bool is_private_mmio_noop(u64 addr) {return false; }
> +static void enc_init_noop(void) { }
>   
>   struct x86_platform_ops x86_platform __ro_after_init = {
>   	.calibrate_cpu			= native_calibrate_cpu_early,
> @@ -158,6 +159,7 @@ struct x86_platform_ops x86_platform __ro_after_init = {
>   		.enc_status_change_finish  = enc_status_change_finish_noop,
>   		.enc_tlb_flush_required	   = enc_tlb_flush_required_noop,
>   		.enc_cache_flush_required  = enc_cache_flush_required_noop,
> +		.enc_init		   = enc_init_noop,
>   	},
>   };
>   
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index 9f27e14e185f..01abecc9a774 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -84,5 +84,8 @@ void __init mem_encrypt_init(void)
>   	/* Call into SWIOTLB to update the SWIOTLB DMA buffers */
>   	swiotlb_update_mem_attributes();
>   
> +	if (x86_platform.guest.enc_init)
> +		x86_platform.guest.enc_init();
> +
>   	print_mem_encrypt_feature_info();
>   }