Hello Tom,
On 2/7/2025 3:45 PM, Tom Lendacky wrote:
> On 2/3/25 15:56, Ashish Kalra wrote:
>> From: Sean Christopherson <seanjc@xxxxxxxxxx>
>>
>> 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@xxxxxxxxxx>
>> Co-developed-by: Ashish Kalra <ashish.kalra@xxxxxxx>
>> Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
>> ---
>> 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.
>
Yes the booting will be parallelized, but the main reason we needed to
explicitly initialize the PSP driver from KVM module load time was that
for the built-in modules case, KVM module was being loaded before the PSP
driver, as per the order of compilation of modules.
So as kvm_amd module will be loading before CCP driver, therefore,
i don't believe kvm module load -> sev_module_init() -> sp_mod_init() can execute
concurrently with CCP module probe -> sp_mod_init().
Therefore i believe, the above code in sp_mod_init() should be safe.
And sev_module_init() is only called in case kvm_amd module is built-in.
Thanks,
Ashish
> If we don't need that:
>
> Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
>
> 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
>> *
