59 lines
1.9 KiB
Diff
59 lines
1.9 KiB
Diff
From 7b41a615bd0f13959d9236abd341879c80379069 Mon Sep 17 00:00:00 2001
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From: Josh Poimboeuf <jpoimboe@redhat.com>
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Date: Tue, 2 Apr 2019 10:00:51 -0500
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Subject: [PATCH 20/30] x86/speculation/mds: Add SMT warning message
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commit 39226ef02bfb43248b7db12a4fdccb39d95318e3 upstream
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MDS is vulnerable with SMT. Make that clear with a one-time printk
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whenever SMT first gets enabled.
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Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Reviewed-by: Tyler Hicks <tyhicks@canonical.com>
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Acked-by: Jiri Kosina <jkosina@suse.cz>
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---
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arch/x86/kernel/cpu/bugs.c | 8 ++++++++
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1 file changed, 8 insertions(+)
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diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
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index 6ccbcac2cb1d..8e74282da80e 100644
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--- a/arch/x86/kernel/cpu/bugs.c
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+++ b/arch/x86/kernel/cpu/bugs.c
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@@ -659,6 +659,9 @@ static void update_indir_branch_cond(void)
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static_branch_disable(&switch_to_cond_stibp);
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}
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+#undef pr_fmt
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+#define pr_fmt(fmt) fmt
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+
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/* Update the static key controlling the MDS CPU buffer clear in idle */
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static void update_mds_branch_idle(void)
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{
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@@ -679,6 +682,8 @@ static void update_mds_branch_idle(void)
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static_branch_disable(&mds_idle_clear);
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}
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+#define MDS_MSG_SMT "MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details.\n"
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+
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void arch_smt_update(void)
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{
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/* Enhanced IBRS implies STIBP. No update required. */
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@@ -702,6 +707,8 @@ void arch_smt_update(void)
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switch (mds_mitigation) {
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case MDS_MITIGATION_FULL:
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case MDS_MITIGATION_VMWERV:
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+ if (sched_smt_active() && !boot_cpu_has(X86_BUG_MSBDS_ONLY))
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+ pr_warn_once(MDS_MSG_SMT);
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update_mds_branch_idle();
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break;
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case MDS_MITIGATION_OFF:
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@@ -1131,6 +1138,7 @@ static int __init l1tf_cmdline(char *str)
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early_param("l1tf", l1tf_cmdline);
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#undef pr_fmt
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+#define pr_fmt(fmt) fmt
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#ifdef CONFIG_SYSFS
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