From nobody Wed Feb 11 01:26:00 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D2D323F8ED for ; Sun, 21 Apr 2024 19:17:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713727052; cv=none; b=HDGMoBmrZsqkJGsZAYLlLGKbTppn4uv71UeQvNpo5s8sBm7fFco7lNkdb3KwQ4QvRWCs8dBQl6LDMZhy8H00Kenxl3Jj3fkmtuqFhgS8clHCCDqW5g0nRo0FW7zVTDRlWLXWSC0AAMkI0JwdB72ZN6qUOmnBXrOpti3KT0wJmKA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713727052; c=relaxed/simple; bh=J0OuVPrjKnI+2yDEh2HpOwIHUwKzrGSnjwOnVRO+I9w=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Q2/Xs2jLxPNnaPFcqQWJJKn3RoJE5amo95wFN2Hpe0iZVN732hW84SE6gRTebIxEhy5NIwIUpGayN2ghmuMx5jbsXd8Q/zKQyjWrA2yptVSVMghLSXKrLL3hVue+XoZ8KxXp1qi2a56A5tI0Fb+oZSQI+4FuhDr+XTNltjBBEXM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Lo50098D; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Lo50098D" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4397CC113CE; Sun, 21 Apr 2024 19:17:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1713727052; bh=J0OuVPrjKnI+2yDEh2HpOwIHUwKzrGSnjwOnVRO+I9w=; h=From:To:Cc:Subject:Date:From; b=Lo50098Dwtw0gXq6T/8vjxoZxdE43Ngplj+Obijq6Z6mDLMdct9VdG2tJ74CZS5RK clS1QjzfncEq24hRCG1AE7eP0CwdSRPoX0E0s5c12JUgc7g+IsHcXStVtW7k71ape7 79WpxIXrDLU8G8HEaTshLtRSDPei0B7cOJkokNEDJpWIjCuRnfiYCTl3YwYRB2HA6n rKvPvz2l+P79Kpoj1QVoF7TVAaTliS7I95amvGiziLJ2OHet3llbTldB2yzRzNkvex ItxEopqR/gqmLtntj5cW3rm7r/I1n0sVHxm72GBE10vUgPgp6DLC1nom2wesav3/+G 6uLJruFrwcBsQ== From: bp@kernel.org To: X86 ML Cc: LKML , David Kaplan , Borislav Petkov Subject: [PATCH] x86/cpu: Fix check for RDPKRU in __show_regs() Date: Sun, 21 Apr 2024 21:17:28 +0200 Message-ID: <20240421191728.32239-1-bp@kernel.org> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: David Kaplan cpu_feature_enabled(X86_FEATURE_OSPKE) does not necessarily reflect whether CR4.PKE is set on the CPU. In particular, they may differ on non-BSP CPUs before setup_pku() is executed. In this scenario, RDPKRU will #UD causing the system to hang. Fix by checking CR4 for PKE enablement which is always correct for the current CPU. The scenario happens by inserting a WARN* before setup_pku() in identiy_cpu() or some other diagnostic which would lead to calling __show_regs(). [ bp: Massage commit message. ] Signed-off-by: David Kaplan Signed-off-by: Borislav Petkov (AMD) --- arch/x86/kernel/process_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 7062b84dd467..6d3d20e3e43a 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -139,7 +139,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_m= ode mode, log_lvl, d3, d6, d7); } =20 - if (cpu_feature_enabled(X86_FEATURE_OSPKE)) + if (cr4 & X86_CR4_PKE) printk("%sPKRU: %08x\n", log_lvl, read_pkru()); } =20 --=20 2.43.0