linux-kernel - Re: [PATCH v17 059/116] KVM: TDX: Create initial guest memory

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Message-ID: <e3e71256-3673-495e-a4b7-985c4aac4bd2@linux.intel.com>
Date:   Fri, 17 Nov 2023 13:25:57 +0800
From:   Binbin Wu <binbin.wu@...ux.intel.com>
To:     Isaku Yamahata <isaku.yamahata@...ux.intel.com>
Cc:     isaku.yamahata@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, isaku.yamahata@...il.com,
        Paolo Bonzini <pbonzini@...hat.com>, erdemaktas@...gle.com,
        Sean Christopherson <seanjc@...gle.com>,
        Sagi Shahar <sagis@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Kai Huang <kai.huang@...el.com>,
        Zhi Wang <zhi.wang.linux@...il.com>, chen.bo@...el.com,
        hang.yuan@...el.com, tina.zhang@...el.com, gkirkpatrick@...gle.com
Subject: Re: [PATCH v17 059/116] KVM: TDX: Create initial guest memory



On 11/17/2023 8:04 AM, Isaku Yamahata wrote:
> On Thu, Nov 16, 2023 at 02:35:33PM +0800,
> Binbin Wu <binbin.wu@...ux.intel.com> wrote:
>
>>
>> On 11/7/2023 10:56 PM, isaku.yamahata@...el.com wrote:
>>> From: Isaku Yamahata <isaku.yamahata@...el.com>
>>>
>>> Because the guest memory is protected in TDX, the creation of the initial
>>> guest memory requires a dedicated TDX module API, tdh_mem_page_add, instead
>>> of directly copying the memory contents into the guest memory in the case
>>> of the default VM type.  KVM MMU page fault handler callback,
>>> private_page_add, handles it.
>>>
>>> Define new subcommand, KVM_TDX_INIT_MEM_REGION, of VM-scoped
>>> KVM_MEMORY_ENCRYPT_OP.  It assigns the guest page, copies the initial
>>> memory contents into the guest memory, encrypts the guest memory.  At the
>>> same time, optionally it extends memory measurement of the TDX guest.  It
>>> calls the KVM MMU page fault(EPT-violation) handler to trigger the
>>> callbacks for it.
>>>
>>> Reported-by: gkirkpatrick@...gle.com
>>> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
>>>
>>> ---
>>> v15 -> v16:
>>> - add check if nr_pages isn't large with
>>>     (nr_page << PAGE_SHIFT) >> PAGE_SHIFT
>>>
>>> v14 -> v15:
>>> - add a check if TD is finalized or not to tdx_init_mem_region()
>>> - return -EAGAIN when partial population
>>> ---
>>>    arch/x86/include/uapi/asm/kvm.h       |   9 ++
>>>    arch/x86/kvm/mmu/mmu.c                |   1 +
>>>    arch/x86/kvm/vmx/tdx.c                | 167 +++++++++++++++++++++++++-
>>>    arch/x86/kvm/vmx/tdx.h                |   2 +
>>>    tools/arch/x86/include/uapi/asm/kvm.h |   9 ++
>>>    5 files changed, 185 insertions(+), 3 deletions(-)
>>>
>> [...]
>>> +static int tdx_sept_page_add(struct kvm *kvm, gfn_t gfn,
>>> +			     enum pg_level level, kvm_pfn_t pfn)
>> For me, the function name is a bit confusing.
>> I would relate it to a SEPT table page instead of a normal private page if
>> only by the function name.
>>
>> Similar to tdx_sept_page_aug(), though it's less confusing due to there is
>> no seam call to aug a sept table page.
> How about tdx_mem_page_{add, aug}()?

It looks good to me.