linux-kernel - Re: [PATCH v6 04/16] KVM: TDX: Pass size to tdx_measure

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Date:   Thu, 16 Nov 2023 16:36:49 -0800
From:   Isaku Yamahata <isaku.yamahata@...ux.intel.com>
To:     Binbin Wu <binbin.wu@...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,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        isaku.yamahata@...ux.intel.com
Subject: Re: [PATCH v6 04/16] KVM: TDX: Pass size to tdx_measure_page()

On Thu, Nov 16, 2023 at 04:57:26PM +0800,
Binbin Wu <binbin.wu@...ux.intel.com> wrote:

> 
> 
> On 11/7/2023 11:00 PM, isaku.yamahata@...el.com wrote:
> > From: Xiaoyao Li <xiaoyao.li@...el.com>
> > 
> > Extend tdx_measure_page() to pass size info so that it can measure
> > large page as well.
> > 
> > Signed-off-by: Xiaoyao Li <xiaoyao.li@...el.com>
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> > ---
> >   arch/x86/kvm/vmx/tdx.c | 8 +++++---
> >   1 file changed, 5 insertions(+), 3 deletions(-)
> > 
> > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> > index 2d5c86e06c5f..a728175c4a6d 100644
> > --- a/arch/x86/kvm/vmx/tdx.c
> > +++ b/arch/x86/kvm/vmx/tdx.c
> > @@ -1434,13 +1434,15 @@ void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int pgd_level)
> >   	td_vmcs_write64(to_tdx(vcpu), SHARED_EPT_POINTER, root_hpa & PAGE_MASK);
> >   }
> > -static void tdx_measure_page(struct kvm_tdx *kvm_tdx, hpa_t gpa)
> > +static void tdx_measure_page(struct kvm_tdx *kvm_tdx, hpa_t gpa, int size)
> IMHO, it's better to pass kvm page level instead of size here to align with
> other APIs.
> 
> >   {
> >   	struct tdx_module_args out;
> >   	u64 err;
> >   	int i;
> > -	for (i = 0; i < PAGE_SIZE; i += TDX_EXTENDMR_CHUNKSIZE) {
> > +	WARN_ON_ONCE(size % TDX_EXTENDMR_CHUNKSIZE);
> 
> If passed level instead of size, then no need to check KVM_HPAGE_SIZE(level)
> against TDX_EXTENDMR_CHUNKSIZE
> 
> But same qeustion, tdx_measure_page() is only for tdh_mem_page_add(), is
> this
> change necessary?

You're right. As tdx_mem_page_add() is the only caller of tdx_measure_page(),
open-code it into tdx_mem_page_add() and drop this patch.
-- 
Isaku Yamahata <isaku.yamahata@...ux.intel.com>