linux-kernel - Re: [PATCH v2 4/9] crypto: ccp: Register SNP panic notifier only if SNP is enabled

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Message-ID: <CAAH4kHai4mqmY6CB3Ybk6JxD7M=OX44k0S=2n_h_F4mVSVco6w@mail.gmail.com>
Date: Tue, 17 Dec 2024 14:51:47 -0800
From: Dionna Amalie Glaze <dionnaglaze@...gle.com>
To: Ashish Kalra <Ashish.Kalra@....com>
Cc: 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, thomas.lendacky@....com, john.allen@....com, 
	herbert@...dor.apana.org.au, davem@...emloft.net, michael.roth@....com, 
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-crypto@...r.kernel.org, linux-coco@...ts.linux.dev
Subject: Re: [PATCH v2 4/9] crypto: ccp: Register SNP panic notifier only if
 SNP is enabled

On Mon, Dec 16, 2024 at 3:58 PM Ashish Kalra <Ashish.Kalra@....com> 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.
>
> Currently the SNP panic notifier is being registered
> irrespective of SNP being enabled/initialized and with this
> change the SNP panic notifier is registered only if SNP
> support is enabled and initialized.
>
> 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 9632a9a5c92e..7c15dec55f58 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;
> @@ -1751,6 +1761,9 @@ 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;
>
> @@ -2490,10 +2503,6 @@ 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)
>  {
> @@ -2542,8 +2551,6 @@ 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:
> @@ -2561,6 +2568,4 @@ void sev_pci_exit(void)
>
>         sev_firmware_shutdown(sev);
>
> -       atomic_notifier_chain_unregister(&panic_notifier_list,
> -                                        &snp_panic_notifier);
>  }
> --
> 2.34.1
>

Reviewed-by: Dionna Glaze <dionnaglaze@...gle.com>

-- 
-Dionna Glaze, PhD, CISSP, CCSP (she/her)