linux-kernel - Re: [PATCH 11/25] KVM: TDX: Report kvm_tdx_caps in KVM_TDX

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Message-ID: <d8cc987e-8007-4820-b493-df2364b31774@suse.com>
Date: Mon, 19 Aug 2024 13:24:53 +0300
From: Nikolay Borisov <nik.borisov@...e.com>
To: Chao Gao <chao.gao@...el.com>, Rick Edgecombe <rick.p.edgecombe@...el.com>
Cc: seanjc@...gle.com, pbonzini@...hat.com, kvm@...r.kernel.org,
 kai.huang@...el.com, isaku.yamahata@...il.com,
 tony.lindgren@...ux.intel.com, xiaoyao.li@...el.com,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/25] KVM: TDX: Report kvm_tdx_caps in
 KVM_TDX_CAPABILITIES



On 13.08.24 г. 6:35 ч., Chao Gao wrote:
> On Mon, Aug 12, 2024 at 03:48:06PM -0700, Rick Edgecombe wrote:
>> From: Xiaoyao Li <xiaoyao.li@...el.com>
>>
>> Report raw capabilities of TDX module to userspace isn't so useful
>> and incorrect, because some of the capabilities might not be supported
>> by KVM.
>>
>> Instead, report the KVM capp'ed capbilities to userspace.
>>
>> Removed the supported_gpaw field. Because CPUID.0x80000008.EAX[23:16] of
>> KVM_SUPPORTED_CPUID enumerates the 5 level EPT support, i.e., if GPAW52
>> is supported or not. Note, GPAW48 should be always supported. Thus no
>> need for explicit enumeration.
>>
>> Signed-off-by: Xiaoyao Li <xiaoyao.li@...el.com>
>> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
>> ---
>> uAPI breakout v1:
>> - Code change due to previous patches changed to use exported 'struct
>>    tdx_sysinfo' pointer.
>> ---
>> arch/x86/include/uapi/asm/kvm.h | 14 +++----------
>> arch/x86/kvm/vmx/tdx.c          | 36 ++++++++-------------------------
>> 2 files changed, 11 insertions(+), 39 deletions(-)
>>
>> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
>> index c9eb2e2f5559..2e3caa5a58fd 100644
>> --- a/arch/x86/include/uapi/asm/kvm.h
>> +++ b/arch/x86/include/uapi/asm/kvm.h
>> @@ -961,18 +961,10 @@ struct kvm_tdx_cpuid_config {
>> 	__u32 edx;
>> };
>>
>> -/* supported_gpaw */
>> -#define TDX_CAP_GPAW_48	(1 << 0)
>> -#define TDX_CAP_GPAW_52	(1 << 1)
>> -
>> struct kvm_tdx_capabilities {
>> -	__u64 attrs_fixed0;
>> -	__u64 attrs_fixed1;
>> -	__u64 xfam_fixed0;
>> -	__u64 xfam_fixed1;
>> -	__u32 supported_gpaw;
>> -	__u32 padding;
>> -	__u64 reserved[251];
>> +	__u64 supported_attrs;
>> +	__u64 supported_xfam;
>> +	__u64 reserved[254];
> 
> I wonder why this patch and patch 9 weren't squashed together. Many changes
> added by patch 9 are removed here.

As far as I can see this patch depends on the code in patch 10 
(kvm_tdx_caps) so this patch definitely must come after changes 
introduced in patch 10. However, patch 9 seems completely independent of 
patch 10, so I think patch 10 should become patch 9, and patch 9/11 
should be squashed into one and become patch 10.

<snip>