From: Yosry Ahmed <yosry.ahmed@linux.dev>
To: x86@kernel.org
Cc: 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>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 3/6] x86/bugs: Remove the X86_FEATURE_USE_IBPB check in ib_prctl_set()
Date: Wed, 19 Feb 2025 22:08:23 +0000 [thread overview]
Message-ID: <20250219220826.2453186-4-yosry.ahmed@linux.dev> (raw)
In-Reply-To: <20250219220826.2453186-1-yosry.ahmed@linux.dev>
If X86_FEATURE_USE_IBPB is not set, then both spectre_v2_user_ibpb and
spectre_v2_user_stibp are set to SPECTRE_V2_USER_NONE in
spectre_v2_user_select_mitigation(). Since ib_prctl_set() already checks
for this before performing the IBPB, the X86_FEATURE_USE_IBPB check is
redundant. Remove it.
Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
---
arch/x86/kernel/cpu/bugs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index fc7ce7a2fc495..a5d0998d76049 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -2272,7 +2272,7 @@ static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
if (ctrl == PR_SPEC_FORCE_DISABLE)
task_set_spec_ib_force_disable(task);
task_update_spec_tif(task);
- if (task == current && cpu_feature_enabled(X86_FEATURE_USE_IBPB))
+ if (task == current)
indirect_branch_prediction_barrier();
break;
default:
--
2.48.1.601.g30ceb7b040-goog
next prev parent reply other threads:[~2025-02-19 22:08 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-19 22:08 [PATCH 0/6] IBPB cleanups and a fixup Yosry Ahmed
2025-02-19 22:08 ` [PATCH 1/6] x86/bugs: Move the X86_FEATURE_USE_IBPB check into callers Yosry Ahmed
2025-02-25 19:47 ` Sean Christopherson
2025-02-25 21:28 ` Yosry Ahmed
2025-02-19 22:08 ` [PATCH 2/6] x86/mm: Remove X86_FEATURE_USE_IBPB checks in cond_mitigation() Yosry Ahmed
2025-02-19 22:08 ` Yosry Ahmed [this message]
2025-02-19 22:08 ` [PATCH 4/6] x86/bugs: Use a static branch to guard IBPB on vCPU load Yosry Ahmed
2025-02-25 19:49 ` Sean Christopherson
2025-02-25 21:27 ` Yosry Ahmed
2025-02-25 22:40 ` Sean Christopherson
2025-02-26 2:49 ` Yosry Ahmed
2025-02-27 0:46 ` Sean Christopherson
2025-02-27 0:54 ` Yosry Ahmed
2025-02-19 22:08 ` [PATCH 5/6] KVM: nVMX: Always use IBPB to properly virtualize IBRS Yosry Ahmed
2025-02-19 23:09 ` Jim Mattson
2025-02-25 19:50 ` Sean Christopherson
2025-02-19 22:08 ` [PATCH 6/6] x86/bugs: Remove X86_FEATURE_USE_IBPB Yosry Ahmed
2025-02-20 19:04 ` [PATCH 0/6] IBPB cleanups and a fixup Josh Poimboeuf
2025-02-20 19:59 ` Yosry Ahmed
2025-02-20 20:47 ` Josh Poimboeuf
2025-02-20 21:50 ` Yosry Ahmed
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