linux-kernel - Re: [PATCH 4/7] crypto: ccp: Register SNP panic notifier only if SNP is enabled

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Message-ID: <0c20c9d1-fdd7-4f2b-73f6-990aaa84a235@amd.com>
Date: Tue, 10 Dec 2024 15:55:54 -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
Cc: michael.roth@....com, dionnaglaze@...gle.com, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
 linux-coco@...ts.linux.dev
Subject: Re: [PATCH 4/7] crypto: ccp: Register SNP panic notifier only if SNP
 is enabled

On 12/9/24 17:25, Ashish Kalra wrote:
> From: Ashish Kalra <ashish.kalra@....com>
> 
> Register the SNP panic notifier if and only if SNP is actually
> initialized and deregistering the notifier when shutting down
> SNP in PSP driver when KVM module is unloaded.

Talk about why you are making the change.

Thanks,
Tom

> 
> Signed-off-by: Ashish Kalra <ashish.kalra@....com>
> ---
>  drivers/crypto/ccp/sev-dev.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index bc121ad9ec26..21faf4c4c4ec 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -109,6 +109,13 @@ static void *sev_init_ex_buffer;
>   */
>  static struct sev_data_range_list *snp_range_list;
>  
> +static int snp_shutdown_on_panic(struct notifier_block *nb,
> +				 unsigned long reason, void *arg);
> +
> +static struct notifier_block snp_panic_notifier = {
> +	.notifier_call = snp_shutdown_on_panic,
> +};
> +
>  static inline bool sev_version_greater_or_equal(u8 maj, u8 min)
>  {
>  	struct sev_device *sev = psp_master->sev_data;
> @@ -1191,6 +1198,9 @@ static int __sev_snp_init_locked(int *error)
>  	dev_info(sev->dev, "SEV-SNP API:%d.%d build:%d\n", sev->api_major,
>  		 sev->api_minor, sev->build);
>  
> +	atomic_notifier_chain_register(&panic_notifier_list,
> +				       &snp_panic_notifier);
> +
>  	sev_es_tmr_size = SNP_TMR_SIZE;
>  
>  	return 0;
> @@ -1750,6 +1760,9 @@ static int __sev_snp_shutdown_locked(int *error, bool panic)
>  	sev->snp_initialized = false;
>  	dev_dbg(sev->dev, "SEV-SNP firmware shutdown\n");
>  
> +	atomic_notifier_chain_unregister(&panic_notifier_list,
> +					 &snp_panic_notifier);
> +
>  	/* Reset TMR size back to default */
>  	sev_es_tmr_size = SEV_TMR_SIZE;
>  
> @@ -2489,10 +2502,6 @@ static int snp_shutdown_on_panic(struct notifier_block *nb,
>  	return NOTIFY_DONE;
>  }
>  
> -static struct notifier_block snp_panic_notifier = {
> -	.notifier_call = snp_shutdown_on_panic,
> -};
> -
>  int sev_issue_cmd_external_user(struct file *filep, unsigned int cmd,
>  				void *data, int *error)
>  {
> @@ -2541,8 +2550,6 @@ void sev_pci_init(void)
>  	dev_info(sev->dev, "SEV%s API:%d.%d build:%d\n", sev->snp_initialized ?
>  		"-SNP" : "", sev->api_major, sev->api_minor, sev->build);
>  
> -	atomic_notifier_chain_register(&panic_notifier_list,
> -				       &snp_panic_notifier);
>  	return;
>  
>  err:
> @@ -2560,6 +2567,4 @@ void sev_pci_exit(void)
>  
>  	sev_firmware_shutdown(sev);
>  
> -	atomic_notifier_chain_unregister(&panic_notifier_list,
> -					 &snp_panic_notifier);
>  }