linux-kernel - Re: [PATCH v2 09/21] x86/virt/tdx: Get information about TDX module and convertible memory

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Date:   Tue, 29 Mar 2022 12:40:35 +1300
From:   Kai Huang <kai.huang@...el.com>
To:     Dave Hansen <dave.hansen@...el.com>,
        Isaku Yamahata <isaku.yamahata@...il.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        seanjc@...gle.com, pbonzini@...hat.com,
        kirill.shutemov@...ux.intel.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, peterz@...radead.org,
        tony.luck@...el.com, ak@...ux.intel.com, dan.j.williams@...el.com,
        isaku.yamahata@...el.com
Subject: Re: [PATCH v2 09/21] x86/virt/tdx: Get information about TDX module
 and convertible memory

On Mon, 2022-03-28 at 13:30 -0700, Dave Hansen wrote:
> On 3/28/22 13:22, Isaku Yamahata wrote:
> > > > > +	/*
> > > > > +	 * Also a sane BIOS should never generate invalid CMR(s) between
> > > > > +	 * two valid CMRs.  Sanity check this and simply return error in
> > > > > +	 * this case.
> > > > > +	 */
> > > > > +	for (j = i; j < cmr_num; j++)
> > > > > +		if (cmr_valid(&cmr_array[j])) {
> > > > > +			pr_err("Firmware bug: invalid CMR(s) among valid CMRs.\n");
> > > > > +			return -EFAULT;
> > > > > +		}
> > > > This check doesn't make sense because above i-for loop has break.
> > > The break in above i-for loop will hit at the first invalid CMR entry.  Yes "j =
> > > i" will make double check on this invalid CMR entry, but it should have no
> > > problem.  Or we can change to "j = i + 1" to skip the first invalid CMR entry.
> > > 
> > > Does this make sense?
> > It makes sense. Somehow I missed j = i. I scratch my review.
> 
> You can also take it as something you might want to refactor, add
> comments, or work on better variable names.  If it confused one person,
> it will confuse more in the future.

Hi Dave,

OK I'll think over whether I can improve.  Thanks for advice.

Btw if you have time, could you help to review this series? Or could you take a
look at whether the overall design is OK, for instance, the design limitations
described in the cover letter?

-- 
Thanks,
-Kai