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Date:   Mon, 19 Jun 2023 16:50:12 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
Cc:     linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
        dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
        gorcunov@openvz.org, suresh.b.siddha@intel.com,
        Kishon Vijay Abraham I <kvijayab@amd.com>,
        Vasant Hegde <vasant.hegde@amd.com>
Subject: Re: [PATCH v1] x86/apic: Fix kernel panic when "intremap=off" and
 "x2apic_phys" are set
Message-ID: <20230619145012.GCZJBrJKuiape5djVt@fat_crate.local>
References: <20230616212236.1389-1-dheerajkumar.srivastava@amd.com>
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On Sat, Jun 17, 2023 at 02:52:36AM +0530, Dheeraj Kumar Srivastava wrote:
> x2APIC mode requires "Interrupt Remapping" to be enabled and the
> "physical x2apic" driver can be used only when x2APIC mode is enabled.
> However when "intremap=off" and "x2apic_phys" kernel command line
> parameters are passed, "physical x2apic" driver is being used even when
> x2APIC mode is disabled ("intremap=off" disables x2APIC mode).
> This results in the below kernel panic:
> 
>   unchecked MSR access error: RDMSR from 0x80f at rIP: 0xffffffff87eab4ec

Not a kernel panic - that's a warning about accessing a non-existent
MSR.

Can you send full dmesg? Privately is fine too.

How exactly do you trigger this? What hw?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette