linux-kernel - Re: [PATCH 06/13] x86/sev: Rename global "sev_enabled" flag to "sev

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Date:   Mon, 11 Jan 2021 10:47:23 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Borislav Petkov <bp@...e.de>,
        Brijesh Singh <brijesh.singh@....com>
Subject: Re: [PATCH 06/13] x86/sev: Rename global "sev_enabled" flag to
 "sev_guest"

On 1/11/21 10:02 AM, Tom Lendacky wrote:
> On 1/8/21 6:47 PM, Sean Christopherson wrote:
>> Use "guest" instead of "enabled" for the global "running as an SEV guest"
>> flag to avoid confusion over whether "sev_enabled" refers to the guest or
>> the host.  This will also allow KVM to usurp "sev_enabled" for its own
>> purposes.
>>
>> No functional change intended.
>>
>> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> 
> Acked-by: Tom Lendacky <thomas.lendacky@....com>

Ah, I tried building with CONFIG_KVM=y and CONFIG_KVM_AMD=y and got a 
build error:

In file included from arch/x86/kvm/svm/svm.c:43:
arch/x86/kvm/svm/svm.h:222:20: error: ‘sev_guest’ redeclared as different 
kind of symbol
   222 | static inline bool sev_guest(struct kvm *kvm)
       |                    ^~~~~~~~~
In file included from ./include/linux/mem_encrypt.h:17,
                  from ./arch/x86/include/asm/page_types.h:7,
                  from ./arch/x86/include/asm/page.h:9,
                  from ./arch/x86/include/asm/thread_info.h:12,
                  from ./include/linux/thread_info.h:38,
                  from ./arch/x86/include/asm/preempt.h:7,
                  from ./include/linux/preempt.h:78,
                  from ./include/linux/percpu.h:6,
                  from ./include/linux/context_tracking_state.h:5,
                  from ./include/linux/hardirq.h:5,
                  from ./include/linux/kvm_host.h:7,
                  from arch/x86/kvm/svm/svm.c:3:
./arch/x86/include/asm/mem_encrypt.h:23:13: note: previous declaration of 
‘sev_guest’ was here
    23 | extern bool sev_guest;
       |             ^~~~~~~~~

Thanks,
Tom

> 
>> ---
>>   arch/x86/include/asm/mem_encrypt.h | 2 +-
>>   arch/x86/mm/mem_encrypt.c          | 4 ++--
>>   arch/x86/mm/mem_encrypt_identity.c | 2 +-
>>   3 files changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/mem_encrypt.h 
>> b/arch/x86/include/asm/mem_encrypt.h
>> index 2f62bbdd9d12..9b3990928674 100644
>> --- a/arch/x86/include/asm/mem_encrypt.h
>> +++ b/arch/x86/include/asm/mem_encrypt.h
>> @@ -20,7 +20,7 @@
>>   extern u64 sme_me_mask;
>>   extern u64 sev_status;
>> -extern bool sev_enabled;
>> +extern bool sev_guest;
>>   void sme_encrypt_execute(unsigned long encrypted_kernel_vaddr,
>>                unsigned long decrypted_kernel_vaddr,
>> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
>> index bc0833713be9..0f798355de03 100644
>> --- a/arch/x86/mm/mem_encrypt.c
>> +++ b/arch/x86/mm/mem_encrypt.c
>> @@ -44,7 +44,7 @@ EXPORT_SYMBOL(sme_me_mask);
>>   DEFINE_STATIC_KEY_FALSE(sev_enable_key);
>>   EXPORT_SYMBOL_GPL(sev_enable_key);
>> -bool sev_enabled __section(".data");
>> +bool sev_guest __section(".data");
>>   /* Buffer used for early in-place encryption by BSP, no locking needed */
>>   static char sme_early_buffer[PAGE_SIZE] __initdata __aligned(PAGE_SIZE);
>> @@ -344,7 +344,7 @@ int __init early_set_memory_encrypted(unsigned long 
>> vaddr, unsigned long size)
>>    */
>>   bool sme_active(void)
>>   {
>> -    return sme_me_mask && !sev_enabled;
>> +    return sme_me_mask && !sev_guest;
>>   }
>>   bool sev_active(void)
>> diff --git a/arch/x86/mm/mem_encrypt_identity.c 
>> b/arch/x86/mm/mem_encrypt_identity.c
>> index 6c5eb6f3f14f..91b6b899c02b 100644
>> --- a/arch/x86/mm/mem_encrypt_identity.c
>> +++ b/arch/x86/mm/mem_encrypt_identity.c
>> @@ -545,7 +545,7 @@ void __init sme_enable(struct boot_params *bp)
>>           /* SEV state cannot be controlled by a command line option */
>>           sme_me_mask = me_mask;
>> -        sev_enabled = true;
>> +        sev_guest = true;
>>           physical_mask &= ~sme_me_mask;
>>           return;
>>       }
>>