1. Patchew
  2. linux
  3. [PATCH v4 0/7] Move initializing SEV/SNP functionality to KVM
  4. View patch

[PATCH v4 7/7] crypto: ccp: Move SEV/SNP Platform initialization to KVM

Ashish Kalra posted 7 patches 10 months ago
There is a newer version of this series
[PATCH v4 7/7] crypto: ccp: Move SEV/SNP Platform initialization to KVM
Posted by Ashish Kalra 10 months ago 
From: Ashish Kalra <ashish.kalra@amd.com>

SNP initialization is forced during PSP driver probe purely because SNP
can't be initialized if VMs are running.  But the only in-tree user of
SEV/SNP functionality is KVM, and KVM depends on PSP driver for the same.
Forcing SEV/SNP initialization because a hypervisor could be running
legacy non-confidential VMs make no sense.

This patch removes SEV/SNP initialization from the PSP driver probe
time and moves the requirement to initialize SEV/SNP functionality
to KVM if it wants to use SEV/SNP.

Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Alexey Kardashevskiy <aik@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
 drivers/crypto/ccp/sev-dev.c | 25 +------------------------
 1 file changed, 1 insertion(+), 24 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index f0f3e6d29200..99a663dbc2b6 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -1346,18 +1346,13 @@ static int _sev_platform_init_locked(struct sev_platform_init_args *args)
 	if (sev->state == SEV_STATE_INIT)
 		return 0;
 
-	/*
-	 * Legacy guests cannot be running while SNP_INIT(_EX) is executing,
-	 * so perform SEV-SNP initialization at probe time.
-	 */
 	rc = __sev_snp_init_locked(&args->error);
 	if (rc && rc != -ENODEV) {
 		/*
 		 * Don't abort the probe if SNP INIT failed,
 		 * continue to initialize the legacy SEV firmware.
 		 */
-		dev_err(sev->dev, "SEV-SNP: failed to INIT rc %d, error %#x\n",
-			rc, args->error);
+		dev_err(sev->dev, "SEV-SNP: failed to INIT, continue SEV INIT\n");
 	}
 
 	/* Defer legacy SEV/SEV-ES support if allowed by caller/module. */
@@ -2505,9 +2500,7 @@ EXPORT_SYMBOL_GPL(sev_issue_cmd_external_user);
 void sev_pci_init(void)
 {
 	struct sev_device *sev = psp_master->sev_data;
-	struct sev_platform_init_args args = {0};
 	u8 api_major, api_minor, build;
-	int rc;
 
 	if (!sev)
 		return;
@@ -2530,16 +2523,6 @@ void sev_pci_init(void)
 			 api_major, api_minor, build,
 			 sev->api_major, sev->api_minor, sev->build);
 
-	/* Initialize the platform */
-	args.probe = true;
-	rc = sev_platform_init(&args);
-	if (rc)
-		dev_err(sev->dev, "SEV: failed to INIT error %#x, rc %d\n",
-			args.error, rc);
-
-	dev_info(sev->dev, "SEV%s API:%d.%d build:%d\n", sev->snp_initialized ?
-		"-SNP" : "", sev->api_major, sev->api_minor, sev->build);
-
 	return;
 
 err:
@@ -2550,10 +2533,4 @@ void sev_pci_init(void)
 
 void sev_pci_exit(void)
 {
-	struct sev_device *sev = psp_master->sev_data;
-
-	if (!sev)
-		return;
-
-	sev_firmware_shutdown(sev);
 }
-- 
2.34.1
Re: [PATCH v4 7/7] crypto: ccp: Move SEV/SNP Platform initialization to KVM
Posted by Tom Lendacky 10 months ago 
On 2/19/25 14:55, Ashish Kalra wrote:
> From: Ashish Kalra <ashish.kalra@amd.com>
> 
> SNP initialization is forced during PSP driver probe purely because SNP
> can't be initialized if VMs are running.  But the only in-tree user of
> SEV/SNP functionality is KVM, and KVM depends on PSP driver for the same.
> Forcing SEV/SNP initialization because a hypervisor could be running
> legacy non-confidential VMs make no sense.
> 
> This patch removes SEV/SNP initialization from the PSP driver probe
> time and moves the requirement to initialize SEV/SNP functionality
> to KVM if it wants to use SEV/SNP.
> 
> Suggested-by: Sean Christopherson <seanjc@google.com>
> Reviewed-by: Alexey Kardashevskiy <aik@amd.com>
> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
> ---
>  drivers/crypto/ccp/sev-dev.c | 25 +------------------------
>  1 file changed, 1 insertion(+), 24 deletions(-)
> 
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index f0f3e6d29200..99a663dbc2b6 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -1346,18 +1346,13 @@ static int _sev_platform_init_locked(struct sev_platform_init_args *args)
>  	if (sev->state == SEV_STATE_INIT)
>  		return 0;
>  
> -	/*
> -	 * Legacy guests cannot be running while SNP_INIT(_EX) is executing,
> -	 * so perform SEV-SNP initialization at probe time.
> -	 */
>  	rc = __sev_snp_init_locked(&args->error);
>  	if (rc && rc != -ENODEV) {
>  		/*
>  		 * Don't abort the probe if SNP INIT failed,
>  		 * continue to initialize the legacy SEV firmware.
>  		 */
> -		dev_err(sev->dev, "SEV-SNP: failed to INIT rc %d, error %#x\n",
> -			rc, args->error);
> +		dev_err(sev->dev, "SEV-SNP: failed to INIT, continue SEV INIT\n");

Please don't remove the error information.

>  	}
>  
>  	/* Defer legacy SEV/SEV-ES support if allowed by caller/module. */
> @@ -2505,9 +2500,7 @@ EXPORT_SYMBOL_GPL(sev_issue_cmd_external_user);
>  void sev_pci_init(void)
>  {
>  	struct sev_device *sev = psp_master->sev_data;
> -	struct sev_platform_init_args args = {0};
>  	u8 api_major, api_minor, build;
> -	int rc;
>  
>  	if (!sev)
>  		return;
> @@ -2530,16 +2523,6 @@ void sev_pci_init(void)
>  			 api_major, api_minor, build,
>  			 sev->api_major, sev->api_minor, sev->build);
>  
> -	/* Initialize the platform */
> -	args.probe = true;
> -	rc = sev_platform_init(&args);
> -	if (rc)
> -		dev_err(sev->dev, "SEV: failed to INIT error %#x, rc %d\n",
> -			args.error, rc);
> -
> -	dev_info(sev->dev, "SEV%s API:%d.%d build:%d\n", sev->snp_initialized ?
> -		"-SNP" : "", sev->api_major, sev->api_minor, sev->build);
> -
>  	return;
>  
>  err:
> @@ -2550,10 +2533,4 @@ void sev_pci_init(void)
>  
>  void sev_pci_exit(void)
>  {
> -	struct sev_device *sev = psp_master->sev_data;
> -
> -	if (!sev)
> -		return;
> -
> -	sev_firmware_shutdown(sev);

Should this remain? If there's a bug in KVM that somehow skips the
shutdown call, then SEV will remain initialized. I think the path is
safe to call a second time.

Thanks,
Tom


>  }
Re: [PATCH v4 7/7] crypto: ccp: Move SEV/SNP Platform initialization to KVM
Posted by Kalra, Ashish 10 months ago 
Hello Tom,

On 2/20/2025 2:03 PM, Tom Lendacky wrote:
> On 2/19/25 14:55, Ashish Kalra wrote:
>> From: Ashish Kalra <ashish.kalra@amd.com>
>>
>> SNP initialization is forced during PSP driver probe purely because SNP
>> can't be initialized if VMs are running.  But the only in-tree user of
>> SEV/SNP functionality is KVM, and KVM depends on PSP driver for the same.
>> Forcing SEV/SNP initialization because a hypervisor could be running
>> legacy non-confidential VMs make no sense.
>>
>> This patch removes SEV/SNP initialization from the PSP driver probe
>> time and moves the requirement to initialize SEV/SNP functionality
>> to KVM if it wants to use SEV/SNP.
>>
>> Suggested-by: Sean Christopherson <seanjc@google.com>
>> Reviewed-by: Alexey Kardashevskiy <aik@amd.com>
>> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
>> ---
>>  drivers/crypto/ccp/sev-dev.c | 25 +------------------------
>>  1 file changed, 1 insertion(+), 24 deletions(-)
>>
>> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
>> index f0f3e6d29200..99a663dbc2b6 100644
>> --- a/drivers/crypto/ccp/sev-dev.c
>> +++ b/drivers/crypto/ccp/sev-dev.c
>> @@ -1346,18 +1346,13 @@ static int _sev_platform_init_locked(struct sev_platform_init_args *args)
>>  	if (sev->state == SEV_STATE_INIT)
>>  		return 0;
>>  
>> -	/*
>> -	 * Legacy guests cannot be running while SNP_INIT(_EX) is executing,
>> -	 * so perform SEV-SNP initialization at probe time.
>> -	 */
>>  	rc = __sev_snp_init_locked(&args->error);
>>  	if (rc && rc != -ENODEV) {
>>  		/*
>>  		 * Don't abort the probe if SNP INIT failed,
>>  		 * continue to initialize the legacy SEV firmware.
>>  		 */
>> -		dev_err(sev->dev, "SEV-SNP: failed to INIT rc %d, error %#x\n",
>> -			rc, args->error);
>> +		dev_err(sev->dev, "SEV-SNP: failed to INIT, continue SEV INIT\n");
> 
> Please don't remove the error information.
> 

The error(s) are already being printed in __sev_snp_init_locked() otherwise the same
error will be printed twice, hence removing it here.

>>  	}
>>  
>>  	/* Defer legacy SEV/SEV-ES support if allowed by caller/module. */
>> @@ -2505,9 +2500,7 @@ EXPORT_SYMBOL_GPL(sev_issue_cmd_external_user);
>>  void sev_pci_init(void)
>>  {
>>  	struct sev_device *sev = psp_master->sev_data;
>> -	struct sev_platform_init_args args = {0};
>>  	u8 api_major, api_minor, build;
>> -	int rc;
>>  
>>  	if (!sev)
>>  		return;
>> @@ -2530,16 +2523,6 @@ void sev_pci_init(void)
>>  			 api_major, api_minor, build,
>>  			 sev->api_major, sev->api_minor, sev->build);
>>  
>> -	/* Initialize the platform */
>> -	args.probe = true;
>> -	rc = sev_platform_init(&args);
>> -	if (rc)
>> -		dev_err(sev->dev, "SEV: failed to INIT error %#x, rc %d\n",
>> -			args.error, rc);
>> -
>> -	dev_info(sev->dev, "SEV%s API:%d.%d build:%d\n", sev->snp_initialized ?
>> -		"-SNP" : "", sev->api_major, sev->api_minor, sev->build);
>> -
>>  	return;
>>  
>>  err:
>> @@ -2550,10 +2533,4 @@ void sev_pci_init(void)
>>  
>>  void sev_pci_exit(void)
>>  {
>> -	struct sev_device *sev = psp_master->sev_data;
>> -
>> -	if (!sev)
>> -		return;
>> -
>> -	sev_firmware_shutdown(sev);
> 
> Should this remain? If there's a bug in KVM that somehow skips the
> shutdown call, then SEV will remain initialized. I think the path is
> safe to call a second time.

Ok.

Thanks,
Ashish
Re: [PATCH v4 7/7] crypto: ccp: Move SEV/SNP Platform initialization to KVM
Posted by Tom Lendacky 10 months ago 
On 2/20/25 14:23, Kalra, Ashish wrote:
> Hello Tom,
> 
> On 2/20/2025 2:03 PM, Tom Lendacky wrote:
>> On 2/19/25 14:55, Ashish Kalra wrote:
>>> From: Ashish Kalra <ashish.kalra@amd.com>
>>>
>>> SNP initialization is forced during PSP driver probe purely because SNP
>>> can't be initialized if VMs are running.  But the only in-tree user of
>>> SEV/SNP functionality is KVM, and KVM depends on PSP driver for the same.
>>> Forcing SEV/SNP initialization because a hypervisor could be running
>>> legacy non-confidential VMs make no sense.
>>>
>>> This patch removes SEV/SNP initialization from the PSP driver probe
>>> time and moves the requirement to initialize SEV/SNP functionality
>>> to KVM if it wants to use SEV/SNP.
>>>
>>> Suggested-by: Sean Christopherson <seanjc@google.com>
>>> Reviewed-by: Alexey Kardashevskiy <aik@amd.com>
>>> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
>>> ---
>>>  drivers/crypto/ccp/sev-dev.c | 25 +------------------------
>>>  1 file changed, 1 insertion(+), 24 deletions(-)
>>>
>>> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
>>> index f0f3e6d29200..99a663dbc2b6 100644
>>> --- a/drivers/crypto/ccp/sev-dev.c
>>> +++ b/drivers/crypto/ccp/sev-dev.c
>>> @@ -1346,18 +1346,13 @@ static int _sev_platform_init_locked(struct sev_platform_init_args *args)
>>>  	if (sev->state == SEV_STATE_INIT)
>>>  		return 0;
>>>  
>>> -	/*
>>> -	 * Legacy guests cannot be running while SNP_INIT(_EX) is executing,
>>> -	 * so perform SEV-SNP initialization at probe time.
>>> -	 */
>>>  	rc = __sev_snp_init_locked(&args->error);
>>>  	if (rc && rc != -ENODEV) {
>>>  		/*
>>>  		 * Don't abort the probe if SNP INIT failed,
>>>  		 * continue to initialize the legacy SEV firmware.
>>>  		 */
>>> -		dev_err(sev->dev, "SEV-SNP: failed to INIT rc %d, error %#x\n",
>>> -			rc, args->error);
>>> +		dev_err(sev->dev, "SEV-SNP: failed to INIT, continue SEV INIT\n");
>>
>> Please don't remove the error information.
>>
> 
> The error(s) are already being printed in __sev_snp_init_locked() otherwise the same
> error will be printed twice, hence removing it here.

Sounds like this change should be in patch #1 then.

Thanks,
Tom

> 
>>>  	}
>>>  
>>>  	/* Defer legacy SEV/SEV-ES support if allowed by caller/module. */
>>> @@ -2505,9 +2500,7 @@ EXPORT_SYMBOL_GPL(sev_issue_cmd_external_user);
>>>  void sev_pci_init(void)
>>>  {
>>>  	struct sev_device *sev = psp_master->sev_data;
>>> -	struct sev_platform_init_args args = {0};
>>>  	u8 api_major, api_minor, build;
>>> -	int rc;
>>>  
>>>  	if (!sev)
>>>  		return;
>>> @@ -2530,16 +2523,6 @@ void sev_pci_init(void)
>>>  			 api_major, api_minor, build,
>>>  			 sev->api_major, sev->api_minor, sev->build);
>>>  
>>> -	/* Initialize the platform */
>>> -	args.probe = true;
>>> -	rc = sev_platform_init(&args);
>>> -	if (rc)
>>> -		dev_err(sev->dev, "SEV: failed to INIT error %#x, rc %d\n",
>>> -			args.error, rc);
>>> -
>>> -	dev_info(sev->dev, "SEV%s API:%d.%d build:%d\n", sev->snp_initialized ?
>>> -		"-SNP" : "", sev->api_major, sev->api_minor, sev->build);
>>> -
>>>  	return;
>>>  
>>>  err:
>>> @@ -2550,10 +2533,4 @@ void sev_pci_init(void)
>>>  
>>>  void sev_pci_exit(void)
>>>  {
>>> -	struct sev_device *sev = psp_master->sev_data;
>>> -
>>> -	if (!sev)
>>> -		return;
>>> -
>>> -	sev_firmware_shutdown(sev);
>>
>> Should this remain? If there's a bug in KVM that somehow skips the
>> shutdown call, then SEV will remain initialized. I think the path is
>> safe to call a second time.
> 
> Ok.
> 
> Thanks,
> Ashish
>

Patchew 2.1-devel-b67e4c2

© 2016 - 2025 Red Hat, Inc.