netdev - Re: [PATCH v5 06/14] x86/ioremap: Support hypervisor specified range to map as encrypted

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Message-ID: <ZAnu/Um+4qq4Owuh@8bytes.org>
Date:   Thu, 9 Mar 2023 15:36:45 +0100
From:   Jörg Rödel <joro@...tes.org>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     Borislav Petkov <bp@...en8.de>,
        David Woodhouse <dwmw2@...radead.org>,
        Dave Hansen <dave.hansen@...el.com>,
        "Michael Kelley (LINUX)" <mikelley@...rosoft.com>,
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        "hpa@...or.com" <hpa@...or.com>, KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "wei.liu@...nel.org" <wei.liu@...nel.org>,
        Dexuan Cui <decui@...rosoft.com>,
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        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
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Subject: Re: [PATCH v5 06/14] x86/ioremap: Support hypervisor specified range
 to map as encrypted

On Thu, Mar 09, 2023 at 08:19:58AM -0600, Tom Lendacky wrote:
> I believe Joerg added that key for performance reasons, since it is used on
> the exception path and can avoid all the calls to cc_platform_has(). I think
> that key should stay.

Yes, that is right. The key is mainly for the NMI entry path which can
be performance relevant in some situations. For SEV-ES some special
handling is needed there to re-enable NMIs and adjust the #VC stack in
case it was raised on the VC-handlers entry path.

Regards,

	Joerg