From: Dave Hansen <dave.hansen@intel.com>
To: Borislav Petkov <bp@alien8.de>, Nikunj A Dadhania <nikunj@amd.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
thomas.lendacky@amd.com, 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 08:38:10 -0700 [thread overview]
Message-ID: <cde957ba-3579-4063-9d17-3630e79ea388@intel.com> (raw)
In-Reply-To: <20260309134640.GOaa7PQJli_C9QATGB@fat_crate.local>
On 3/9/26 06:46, Borislav Petkov wrote:
> My SNP guest stops booting with this right:
Could you dump out CR4 at wakeup_cpu_via_vmgexit() before and after this
patch? Right here:
/* CR4 should maintain the MCE value */
cr4 = native_read_cr4() & X86_CR4_MCE;
It's got to be some delta there.
The other possibility is that some CR4 bit becomes no longer pinned when
the CPU comes up, and the *pinning* was what caused the secondary CPU's
CR4 bit to get set, not its actual initialization.
Basically, the secondary boot code didn't explicitly set a bit and
counted on the pinning code to do it instead.
It's probably exacerbated by the "novel" way that SEV-SNP CPUs get
brought up and all the assembly that *only* runs there.
next prev parent reply other threads:[~2026-03-09 15:38 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 [this message]
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
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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