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Message-ID: <8c99f8d2-247d-ccee-3a0b-e95e547f8b9b@intel.com>
Date:   Mon, 2 Oct 2023 14:41:09 -0700
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Subject: Re: [PATCH v2 2/2] x86/sev-es: Only set x86_virt_bits to correct
 value
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To:     Nathan Chancellor <nathan@kernel.org>,
        Adam Dunlap <acdunlap@google.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Sean Christopherson <seanjc@google.com>,
        Kim Phillips <kim.phillips@amd.com>,
        Juergen Gross <jgross@suse.com>,
        Ashok Raj <ashok.raj@intel.com>,
        Joerg Roedel <jroedel@suse.de>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        David Hildenbrand <david@redhat.com>,
        Mike Rapoport <rppt@kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Nikunj A Dadhania <nikunj@amd.com>,
        Dionna Glaze <dionnaglaze@google.com>,
        Peter Gonda <pgonda@google.com>,
        David Rientjes <rientjes@google.com>,
        Khalid ElMously <khalid.elmously@canonical.com>,
        Jacob Xu <jacobhxu@google.com>, llvm@lists.linux.dev
References: <20230912002703.3924521-1-acdunlap@google.com>
 <20230912002703.3924521-3-acdunlap@google.com>
 <20231002200426.GA4127272@dev-arch.thelio-3990X>
From:   Dave Hansen <dave.hansen@intel.com>
In-Reply-To: <20231002200426.GA4127272@dev-arch.thelio-3990X>
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On 10/2/23 13:04, Nathan Chancellor wrote:
> On Mon, Sep 11, 2023 at 05:27:03PM -0700, Adam Dunlap wrote:
>> Instead of setting x86_virt_bits to a possibly-correct value and then
>> correcting it later, do all the necessary checks before setting it.
>>
>> At this point, the #VC handler references boot_cpu_data.x86_virt_bits,
>> and in the previous version, it would be triggered by the cpuids between
>> the point at which it is set to 48 and when it is set to the correct
>> value.
>>
>> Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
>> Signed-off-by: Adam Dunlap <acdunlap@google.com>
> Our continuous integration started seeing panics when booting ARCH=i386
> without KVM after this change landed in -tip as commit fbf6449f84bf
> ("x86/sev-es: Set x86_virt_bits to the correct value straight away,
> instead of a two-phase approach"):

I can't reproduce this, but I'm running a gcc-built kernel and I haven't
tried very hard to replicate your qemu setup.

I did notice, though, that the patch in question forgot to move one
assignment.  Could you see if the attached patch fixes things for you?
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