linux-kernel - RE: [PATCH v2 1/6] x86/tdx: Retry TDVMCALL_MAP

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Message-ID: <SA1PR21MB133556956745BA16EC2841C9BF1D9@SA1PR21MB1335.namprd21.prod.outlook.com>
Date:   Thu, 8 Dec 2022 19:54:22 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
CC:     "ak@...ux.intel.com" <ak@...ux.intel.com>,
        "arnd@...db.de" <arnd@...db.de>, "bp@...en8.de" <bp@...en8.de>,
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        Haiyang Zhang <haiyangz@...rosoft.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "jane.chu@...cle.com" <jane.chu@...cle.com>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        KY Srinivasan <kys@...rosoft.com>,
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        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
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        "Michael Kelley (LINUX)" <mikelley@...rosoft.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 1/6] x86/tdx: Retry TDVMCALL_MAP_GPA() when needed

> From: Kirill A. Shutemov <kirill@...temov.name>
> Sent: Thursday, December 8, 2022 11:48 AM
> To: Dexuan Cui <decui@...rosoft.com>
> > [...]
> > +static bool tdx_map_gpa(phys_addr_t start, phys_addr_t end, bool enc)
> >  {
> > -	phys_addr_t start = __pa(vaddr);
> > -	phys_addr_t end   = __pa(vaddr + numpages * PAGE_SIZE);
> > +	int max_retry_cnt = 1000, retry_cnt = 0;
> 
> Hm. max_retry_cnt looks too high to me. I expected to see 3 or something.
> 
> Any justification for it to be *that* high?

No. I just used an enough big number :-)
I'll change it to 3 in the next version.