Re: [RFC PATCH v3 04/20] x86: Handle reduction in physical address size with SME

[Tom Lendacky]

On 11/15/2016 6:10 AM, Joerg Roedel wrote:
> On Wed, Nov 09, 2016 at 06:35:13PM -0600, Tom Lendacky wrote:
>> +/*
>> + * AMD Secure Memory Encryption (SME) can reduce the size of the physical
>> + * address space if it is enabled, even if memory encryption is not active.
>> + * Adjust x86_phys_bits if SME is enabled.
>> + */
>> +static void phys_bits_adjust(struct cpuinfo_x86 *c)
>> +{
> 
> Better call this function amd_sme_phys_bits_adjust(). This name makes it
> clear at the call-site why it is there and what it does.

Will do.

> 
>> +	u32 eax, ebx, ecx, edx;
>> +	u64 msr;
>> +
>> +	if (c->x86_vendor != X86_VENDOR_AMD)
>> +		return;
>> +
>> +	if (c->extended_cpuid_level < 0x8000001f)
>> +		return;
>> +
>> +	/* Check for SME feature */
>> +	cpuid(0x8000001f, &eax, &ebx, &ecx, &edx);
>> +	if (!(eax & 0x01))
>> +		return;
> 
> Maybe add a comment here why you can't use cpu_has (yet).
> 

Ok, will do.

Thanks,
Tom