linux-kernel - Re: [PATCH v2 3/3] KVM: SVM: Add support for MPK feature on AMD

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Message-ID: <2f4126c1-3c6f-b2d0-2ebb-80dc8f86304c@amd.com>
Date:   Fri, 8 May 2020 17:02:55 -0500
From:   Babu Moger <babu.moger@....com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     corbet@....net, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
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Subject: Re: [PATCH v2 3/3] KVM: SVM: Add support for MPK feature on AMD



On 5/8/20 4:55 PM, Sean Christopherson wrote:
> On Fri, May 08, 2020 at 04:10:03PM -0500, Babu Moger wrote:
>> The Memory Protection Key (MPK) feature provides a way for applications
>> to impose page-based data access protections (read/write, read-only or
>> no access), without requiring modification of page tables and subsequent
>> TLB invalidations when the application changes protection domains.
>>
>> This feature is already available in Intel platforms. Now enable the
>> feature on AMD platforms.
>>
>> AMD documentation for MPK feature is available at "AMD64 Architecture
>> Programmer’s Manual Volume 2: System Programming, Pub. 24593 Rev. 3.34,
>> Section 5.6.6 Memory Protection Keys (MPK) Bit". Documentation can be
>> obtained at the link below.
>>
>> Link: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.kernel.org%2Fshow_bug.cgi%3Fid%3D206537&amp;data=02%7C01%7Cbabu.moger%40amd.com%7Ceca826ce565e450edc0b08d7f39a95f1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637245717572330988&amp;sdata=IaZXO8LLyXMqP0pZBYKzkXY4cInzpjBbSyzcnIcj%2BoA%3D&amp;reserved=0
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>>  arch/x86/kvm/svm/svm.c |    4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
>> index 2f379bacbb26..37fb41ad9149 100644
>> --- a/arch/x86/kvm/svm/svm.c
>> +++ b/arch/x86/kvm/svm/svm.c
>> @@ -818,6 +818,10 @@ static __init void svm_set_cpu_caps(void)
>>  	if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||
>>  	    boot_cpu_has(X86_FEATURE_AMD_SSBD))
>>  		kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD);
>> +
>> +	/* PKU is not yet implemented for shadow paging. */
>> +	if (npt_enabled && boot_cpu_has(X86_FEATURE_OSPKE))
>> +		kvm_cpu_cap_check_and_set(X86_FEATURE_PKU);
> 
> This can actually be done in common code as well since both VMX and SVM
> call kvm_set_cpu_caps() after kvm_configure_mmu(), i.e. key off of
> tdp_enabled.

Ok. Sure. Will change it in next revision. Thanks.
> 
>>  }
>>  
>>  static __init int svm_hardware_setup(void)
>>