linux-kernel - Re: [PATCH v3 1/3] crypto: ccp: Add external API interface for PSP module initialization

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Message-ID: <2794745e-c33a-68dc-f0e7-961e1631299e@amd.com>
Date: Fri, 7 Feb 2025 15:45:51 -0600
From: Tom Lendacky <thomas.lendacky@....com>
To: Ashish Kalra <Ashish.Kalra@....com>, seanjc@...gle.com,
 pbonzini@...hat.com, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
 dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
 john.allen@....com, herbert@...dor.apana.org.au, davem@...emloft.net,
 joro@...tes.org, suravee.suthikulpanit@....com, will@...nel.org,
 robin.murphy@....com
Cc: michael.roth@....com, dionnaglaze@...gle.com, nikunj@....com,
 ardb@...nel.org, kevinloughlin@...gle.com, Neeraj.Upadhyay@....com,
 kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-crypto@...r.kernel.org, linux-coco@...ts.linux.dev,
 iommu@...ts.linux.dev
Subject: Re: [PATCH v3 1/3] crypto: ccp: Add external API interface for PSP
 module initialization

On 2/3/25 15:56, Ashish Kalra wrote:
> From: Sean Christopherson <seanjc@...gle.com>
> 
> KVM is dependent on the PSP SEV driver and PSP SEV driver needs to be
> loaded before KVM module. In case of module loading any dependent
> modules are automatically loaded but in case of built-in modules there
> is no inherent mechanism available to specify dependencies between
> modules and ensure that any dependent modules are loaded implicitly.
> 
> Add a new external API interface for PSP module initialization which
> allows PSP SEV driver to be loaded explicitly if KVM is built-in.
> 
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> Co-developed-by: Ashish Kalra <ashish.kalra@....com>
> Signed-off-by: Ashish Kalra <ashish.kalra@....com>
> ---
>  drivers/crypto/ccp/sp-dev.c | 14 ++++++++++++++
>  include/linux/psp-sev.h     |  9 +++++++++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/drivers/crypto/ccp/sp-dev.c b/drivers/crypto/ccp/sp-dev.c
> index 7eb3e4668286..3467f6db4f50 100644
> --- a/drivers/crypto/ccp/sp-dev.c
> +++ b/drivers/crypto/ccp/sp-dev.c
> @@ -19,6 +19,7 @@
>  #include <linux/types.h>
>  #include <linux/ccp.h>
>  
> +#include "sev-dev.h"
>  #include "ccp-dev.h"
>  #include "sp-dev.h"
>  
> @@ -253,8 +254,12 @@ struct sp_device *sp_get_psp_master_device(void)
>  static int __init sp_mod_init(void)
>  {
>  #ifdef CONFIG_X86
> +	static bool initialized;
>  	int ret;
>  
> +	if (initialized)
> +		return 0;

Do we need any kind of mutex protection here? Is the init process
parallelized? We only have one caller today, so probably not a big deal.

If we don't need that:

Reviewed-by: Tom Lendacky <thomas.lendacky@....com>

Thanks,
Tom

> +
>  	ret = sp_pci_init();
>  	if (ret)
>  		return ret;
> @@ -263,6 +268,8 @@ static int __init sp_mod_init(void)
>  	psp_pci_init();
>  #endif
>  
> +	initialized = true;
> +
>  	return 0;
>  #endif
>  
> @@ -279,6 +286,13 @@ static int __init sp_mod_init(void)
>  	return -ENODEV;
>  }
>  
> +#if IS_BUILTIN(CONFIG_KVM_AMD) && IS_ENABLED(CONFIG_KVM_AMD_SEV)
> +int __init sev_module_init(void)
> +{
> +	return sp_mod_init();
> +}
> +#endif
> +
>  static void __exit sp_mod_exit(void)
>  {
>  #ifdef CONFIG_X86
> diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
> index 903ddfea8585..f3cad182d4ef 100644
> --- a/include/linux/psp-sev.h
> +++ b/include/linux/psp-sev.h
> @@ -814,6 +814,15 @@ struct sev_data_snp_commit {
>  
>  #ifdef CONFIG_CRYPTO_DEV_SP_PSP
>  
> +/**
> + * sev_module_init - perform PSP SEV module initialization
> + *
> + * Returns:
> + * 0 if the PSP module is successfully initialized
> + * negative value if the PSP module initialization fails
> + */
> +int sev_module_init(void);
> +
>  /**
>   * sev_platform_init - perform SEV INIT command
>   *