From: Dave Hansen <dave.hansen@intel.com>
To: Borislav Petkov <bp@alien8.de>, Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Kim Phillips <kim.phillips@amd.com>,
x86@kernel.org, Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Joao Martins <joao.m.martins@oracle.com>,
Jonathan Corbet <corbet@lwn.net>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
David Woodhouse <dwmw@amazon.co.uk>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Juergen Gross <jgross@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Tony Luck <tony.luck@intel.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Alexey Kardashevskiy <aik@amd.com>,
kvm@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/CPU/AMD: Make sure EFER[AIBRSE] is set
Date: Mon, 27 Feb 2023 07:25:00 -0800 [thread overview]
Message-ID: <445daef5-8417-ddbb-abbf-3c5ab38e1c9c@intel.com> (raw)
In-Reply-To: <Y/n9XcbnCzWv2Vul@zn.tnic>
On 2/25/23 04:21, Borislav Petkov wrote:
> + /*
> + * Make sure EFER[AIBRSE - Automatic IBRS Enable] is set. The APs are brought up
> + * using the trampoline code and as part of it, EFER gets prepared there in order
> + * to be replicated onto them. Regardless, set it here again, if not set, to protect
> + * against any future refactoring/code reorganization which might miss setting
> + * this important bit.
> + */
> + if (spectre_v2_in_ibrs_mode(spectre_v2_enabled) &&
> + cpu_has(c, X86_FEATURE_AUTOIBRS))
> + msr_set_bit(MSR_EFER, _EFER_AUTOIBRS);
> }
I guess the belt and suspenders could be justified here by how important
the bit is.
But, if EFER[AIBRSE] gets clear somehow shouldn't we also dump a warning
out here so the fool who botched it can fix it? Even if AIBRSE is fixed
up, some less important bit could still be botched.
It will freak some users out, but it does seem like the kind of thing we
_want_ a bug report for.
next prev parent reply other threads:[~2023-02-27 15:25 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-24 16:33 [PATCH v9 0/8] x86/cpu, kvm: Support AMD Automatic IBRS Kim Phillips
2023-01-24 16:33 ` [PATCH v9 1/8] x86/cpu, kvm: Add support for CPUID_80000021_EAX Kim Phillips
2023-01-24 16:33 ` [PATCH v9 2/8] KVM: x86: Move open-coded cpuid leaf 0x80000021 EAX bit propagation code Kim Phillips
2023-01-24 16:33 ` [PATCH v9 3/8] x86/cpu, kvm: Add the NO_NESTED_DATA_BP feature Kim Phillips
2023-01-24 16:33 ` [PATCH v9 4/8] x86/cpu, kvm: Move X86_FEATURE_LFENCE_RDTSC to its native leaf Kim Phillips
2023-01-24 21:32 ` Sean Christopherson
2023-01-25 12:09 ` Borislav Petkov
2023-01-24 16:33 ` [PATCH v9 5/8] x86/cpu, kvm: Add the Null Selector Clears Base feature Kim Phillips
2023-01-24 16:33 ` [PATCH v9 6/8] x86/cpu, kvm: Add the SMM_CTL MSR not present feature Kim Phillips
2023-01-24 16:33 ` [PATCH v9 7/8] x86/cpu: Support AMD Automatic IBRS Kim Phillips
2023-02-24 18:52 ` Josh Poimboeuf
2023-02-24 21:08 ` Borislav Petkov
2023-02-24 21:35 ` Josh Poimboeuf
2023-02-24 21:59 ` Borislav Petkov
2023-02-24 22:03 ` Luck, Tony
2023-02-24 22:12 ` Borislav Petkov
2023-02-24 23:30 ` pawan.kumar.gupta
2023-02-24 22:51 ` Borislav Petkov
2023-02-24 23:23 ` Borislav Petkov
2023-02-25 0:09 ` Josh Poimboeuf
2023-02-25 0:20 ` [PATCH] x86/CPU/AMD: Make sure EFER[AIBRSE] is set Borislav Petkov
2023-02-25 0:52 ` Pawan Gupta
2023-02-25 1:32 ` Josh Poimboeuf
2023-02-25 12:21 ` Borislav Petkov
2023-02-25 17:28 ` Josh Poimboeuf
2023-02-25 22:56 ` Borislav Petkov
2023-02-25 23:43 ` Josh Poimboeuf
2023-02-26 11:18 ` Borislav Petkov
2023-02-26 17:27 ` Josh Poimboeuf
2023-02-26 18:44 ` Borislav Petkov
2023-02-27 15:25 ` Dave Hansen [this message]
2023-02-27 15:40 ` Borislav Petkov
2023-02-27 16:39 ` Dave Hansen
2023-03-10 16:22 ` [PATCH -v2] " Borislav Petkov
2023-03-13 15:42 ` Dave Hansen
2023-01-24 16:33 ` [PATCH v9 8/8] KVM: x86: Propagate the AMD Automatic IBRS feature to the guest Kim Phillips
2023-01-24 21:37 ` [PATCH v9 0/8] x86/cpu, kvm: Support AMD Automatic IBRS Sean Christopherson
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