From: Dave Hansen <dave.hansen@intel.com>
To: Tom Lendacky <thomas.lendacky@amd.com>, Borislav Petkov <bp@alien8.de>
Cc: Nikunj A Dadhania <nikunj@amd.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
tglx@kernel.org, mingo@redhat.com, dave.hansen@linux.intel.com,
hpa@zytor.com, xin@zytor.com, seanjc@google.com,
pbonzini@redhat.com, x86@kernel.org, sohil.mehta@intel.com,
jon.grimm@amd.com
Subject: Re: [PATCH v2 1/2] x86/cpu: Disable CR pinning during CPU bringup
Date: Mon, 9 Mar 2026 12:27:14 -0700 [thread overview]
Message-ID: <505a6bbd-3ecf-4de9-8fb9-0b21c3435a96@intel.com> (raw)
In-Reply-To: <7ca205d6-b01b-4ed3-959d-db31a6496d79@amd.com>
On 3/9/26 11:40, Tom Lendacky wrote:
> The SNP guest is dying in __x2apic_enable() when trying to read
> MSR_IA32_APICBASE, which will trigger a #VC.
>
> If I set CR4[16] in cr4_init() then the SNP guest boots fine.
That sounds pretty definitive.
How does this work on the boot CPU? How does it manage to get FSGSBASE
set up before __x2apic_enable()? Or is it on the early exception code,
which might not use FSGSBASE instructions?
Either way, I do think this needs to get fixed up. It was not acceptable
for cr4_init() implicitly to set pinned features and then have the CPU
boot code come along and do:
cr4_set_bits(X86_CR4_FSGSBASE);
It all basically worked by accident before.
next prev parent reply other threads:[~2026-03-09 19:27 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-26 9:23 [PATCH v2 0/2] x86/fred: Fix SEV-ES/SNP guest boot failures Nikunj A Dadhania
2026-02-26 9:23 ` [PATCH v2 1/2] x86/cpu: Disable CR pinning during CPU bringup Nikunj A Dadhania
2026-03-09 13:46 ` Borislav Petkov
2026-03-09 15:38 ` Dave Hansen
2026-03-09 16:15 ` Borislav Petkov
2026-03-09 18:03 ` Dave Hansen
2026-03-09 18:40 ` Tom Lendacky
2026-03-09 19:27 ` Dave Hansen [this message]
2026-03-11 10:41 ` Nikunj A. Dadhania
2026-03-11 14:07 ` Dave Hansen
2026-03-11 15:42 ` Nikunj A. Dadhania
2026-03-11 17:28 ` Dave Hansen
2026-03-12 7:21 ` Nikunj A. Dadhania
2026-03-12 7:26 ` Nikunj A. Dadhania
2026-03-12 14:08 ` Nikunj A. Dadhania
2026-03-12 14:20 ` Dave Hansen
2026-03-12 14:53 ` Nikunj A. Dadhania
2026-03-12 15:02 ` Dave Hansen
2026-03-12 19:06 ` David Laight
2026-03-16 20:27 ` Chang S. Bae
2026-03-16 21:43 ` Dave Hansen
2026-03-17 4:12 ` Nikunj A. Dadhania
2026-03-17 14:26 ` Borislav Petkov
2026-03-17 15:31 ` Dave Hansen
2026-03-17 16:54 ` Borislav Petkov
2026-03-18 8:19 ` Nikunj A. Dadhania
2026-03-17 17:04 ` Chang S. Bae
2026-03-17 17:51 ` Chang S. Bae
2026-03-12 18:09 ` Sohil Mehta
2026-03-13 8:35 ` Nikunj A. Dadhania
2026-03-13 18:05 ` Sohil Mehta
2026-03-13 19:10 ` Borislav Petkov
2026-03-17 17:06 ` Chang S. Bae
2026-02-26 9:23 ` [PATCH v2 2/2] x86/fred: Fix early boot failures on SEV-ES/SNP guests Nikunj A Dadhania
2026-02-26 14:14 ` Tom Lendacky
2026-02-27 4:14 ` Nikunj A. Dadhania
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