From: Andi Kleen <andi@firstfloor.org>
To: speck@linutronix.de
Cc: Andi Kleen <ak@linux.intel.com>
Subject: [MODERATED] [PATCH v6 02/43] MDSv6
Date: Sun, 24 Feb 2019 07:07:08 -0800 [thread overview]
Message-ID: <73fc1e305dd1a511a311a899f9a1859964c29c5f.1551019522.git.ak@linux.intel.com> (raw)
In-Reply-To: <cover.1551019522.git.ak@linux.intel.com>
In-Reply-To: <cover.1551019522.git.ak@linux.intel.com>
Add basic code to clear unconditonally on every kernel exit.
The flushing is provided by new microcode as a new side
effect of the otherwise unused VERW instruction.
Future patches will provide more sophisticated policies
on when to clear.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
arch/x86/entry/common.c | 3 +++
arch/x86/include/asm/clearcpu.h | 23 +++++++++++++++++++++++
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/kernel/nmi.c | 5 ++++-
4 files changed, 31 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/include/asm/clearcpu.h
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 7bc105f47d21..dfd51d97d683 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -29,6 +29,7 @@
#include <asm/desc.h>
#include <asm/traps.h>
#include <asm/vdso.h>
+#include <asm/clearcpu.h>
#include <linux/uaccess.h>
#include <asm/cpufeature.h>
@@ -211,6 +212,8 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs)
ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED);
#endif
+ clear_cpu();
+
user_enter_irqoff();
}
diff --git a/arch/x86/include/asm/clearcpu.h b/arch/x86/include/asm/clearcpu.h
new file mode 100644
index 000000000000..1da885793805
--- /dev/null
+++ b/arch/x86/include/asm/clearcpu.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_CLEARCPU_H
+#define _ASM_CLEARCPU_H 1
+
+#include <linux/jump_label.h>
+#include <linux/sched/smt.h>
+#include <asm/alternative.h>
+#include <linux/thread_info.h>
+
+/*
+ * Clear CPU buffers to avoid side channels.
+ * We use microcode as a side effect of the obsolete VERW instruction
+ */
+
+static inline void clear_cpu(void)
+{
+ unsigned kernel_ds = __KERNEL_DS;
+ /* Has to be memory form, don't modify to use an register */
+ alternative_input("", "verw %[kernelds]", X86_BUG_MDS,
+ [kernelds] "m" (kernel_ds));
+}
+
+#endif
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 9ef6c5dc00dc..233ca598826f 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -344,6 +344,7 @@
/* Intel-defined CPU features, CPUID level 0x00000007:0 (EDX), word 18 */
#define X86_FEATURE_AVX512_4VNNIW (18*32+ 2) /* AVX-512 Neural Network Instructions */
#define X86_FEATURE_AVX512_4FMAPS (18*32+ 3) /* AVX-512 Multiply Accumulation Single precision */
+#define X86_FEATURE_MD_CLEAR (18*32+10) /* Flush state on VERW */
#define X86_FEATURE_PCONFIG (18*32+18) /* Intel PCONFIG */
#define X86_FEATURE_SPEC_CTRL (18*32+26) /* "" Speculation Control (IBRS + IBPB) */
#define X86_FEATURE_INTEL_STIBP (18*32+27) /* "" Single Thread Indirect Branch Predictors */
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 18bc9b51ac9b..1c5507400089 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -494,7 +494,7 @@ do_nmi(struct pt_regs *regs, long error_code)
{
if (this_cpu_read(nmi_state) != NMI_NOT_RUNNING) {
this_cpu_write(nmi_state, NMI_LATCHED);
- return;
+ goto out;
}
this_cpu_write(nmi_state, NMI_EXECUTING);
this_cpu_write(nmi_cr2, read_cr2());
@@ -533,6 +533,9 @@ do_nmi(struct pt_regs *regs, long error_code)
write_cr2(this_cpu_read(nmi_cr2));
if (this_cpu_dec_return(nmi_state))
goto nmi_restart;
+
+out:
+ clear_cpu();
}
NOKPROBE_SYMBOL(do_nmi);
--
2.17.2
next prev parent reply other threads:[~2019-02-24 15:12 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-24 15:07 [MODERATED] [PATCH v6 00/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 01/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` Andi Kleen [this message]
2019-02-24 15:07 ` [MODERATED] [PATCH v6 03/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 04/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 05/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 06/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 07/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 08/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 09/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 10/43] MDSv6 Andi Kleen
2019-02-25 16:11 ` [MODERATED] " Greg KH
2019-02-25 16:42 ` Andi Kleen
2019-02-25 16:30 ` Greg KH
2019-02-25 16:41 ` [MODERATED] Encrypted Message Jon Masters
2019-02-25 16:58 ` [MODERATED] Re: [PATCH v6 10/43] MDSv6 Andi Kleen
2019-02-25 17:18 ` Dave Hansen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 11/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 12/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 13/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 14/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 15/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 16/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 17/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 18/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 19/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 20/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 21/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 22/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 23/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 24/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 25/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 26/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 27/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 28/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 29/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 30/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 31/43] MDSv6 Andi Kleen
2019-02-25 15:19 ` [MODERATED] " Greg KH
2019-02-25 15:34 ` Andi Kleen
2019-02-25 15:49 ` Greg KH
2019-02-25 15:52 ` [MODERATED] Encrypted Message Jon Masters
2019-02-25 16:00 ` [MODERATED] " Greg KH
2019-02-25 16:19 ` [MODERATED] " Jon Masters
2019-02-25 16:19 ` [MODERATED] Re: [PATCH v6 31/43] MDSv6 Andi Kleen
2019-02-25 16:24 ` mark gross
2019-02-25 16:24 ` Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 32/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 33/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 34/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 35/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [FROZEN] [PATCH v6 36/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 37/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 38/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 39/43] MDSv6 Andi Kleen
2019-02-25 15:26 ` [MODERATED] " Greg KH
2019-02-25 16:28 ` Andi Kleen
2019-02-25 16:47 ` Greg KH
2019-02-25 17:05 ` Andi Kleen
2019-02-25 17:49 ` Greg KH
2019-02-25 18:10 ` Andi Kleen
2019-02-25 20:11 ` Greg KH
2019-02-25 21:00 ` Greg KH
2019-02-25 21:19 ` Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 40/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 41/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 42/43] MDSv6 Andi Kleen
2019-02-24 15:07 ` [MODERATED] [PATCH v6 43/43] MDSv6 Andi Kleen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=73fc1e305dd1a511a311a899f9a1859964c29c5f.1551019522.git.ak@linux.intel.com \
--to=andi@firstfloor.org \
--cc=ak@linux.intel.com \
--cc=speck@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).