linux-kernel - Re: [PATCH] x86/sev: Check whether SEV or SME is supported first

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Message-ID: <YLSuRBzM6piigP8t@suse.de>
Date:   Mon, 31 May 2021 11:37:08 +0200
From:   Joerg Roedel <jroedel@...e.de>
To:     Pu Wen <puwen@...on.cn>
Cc:     Sean Christopherson <seanjc@...gle.com>, x86@...nel.org,
        joro@...tes.org, thomas.lendacky@....com,
        dave.hansen@...ux.intel.com, peterz@...radead.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...e.de, hpa@...or.com,
        sashal@...nel.org, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] x86/sev: Check whether SEV or SME is supported first

On Thu, May 27, 2021 at 11:08:32PM +0800, Pu Wen wrote:
> Reading MSR_AMD64_SEV which is not implemented on Hygon Dhyana CPU will cause
> the kernel reboot, and native_read_msr_safe() has no help.

The reason for the reboot is that there is no #GP or #DF handler set up
when this MSR is read, so its propagated to a shutdown event. But there
is an IDT already, so you can set up early and #GP handler to fix the
reboot.

Regards,

	Joerg