The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: abe7c8b09bd72a9c726016257c6281f129b4c02d
Gitweb: https://git.kernel.org/tip/abe7c8b09bd72a9c726016257c6281f129b4c02d
Author: Rik van Riel <riel@surriel.com>
AuthorDate: Thu, 06 Aug 2026 08:54:57 -07:00
Committer: Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Mon, 10 Aug 2026 07:09:18 -07:00
x86/CPU: Add a tlbi= cmdline switch
With the recently found INVLPGB / TLBSYNC issue, there has been some
interest in disabling INVLPGB-based TLB flushing, in order to rule out
that CPU issue as a cause of userspace crashes.
Add a kernel command line option to control the TLB flushing behavior.
If the need arises, we will add a "tlbi=broadcast" for the case when TLB
invalidation broadcasts need to be explicitly selected, but this is not
needed now yet.
[ bp: Rewrite commit message, move to cpu/common.c, add documentation. ]
Fixes: 767ae437a32d ("x86/mm: Add INVLPGB feature and Kconfig entry")
Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260729204341.3eb0b5ea@fangorn
---
Documentation/admin-guide/kernel-parameters.txt | 4 ++++
arch/x86/kernel/cpu/common.c | 10 ++++++++++
2 files changed, 14 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3d35270..e8ff369 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -7568,6 +7568,10 @@ Kernel parameters
See Documentation/admin-guide/mm/transhuge.rst for more
details.
+ tlbi= [X86-64]
+ Format: {ipi}
+ ipi: switch to IPI-based TLB flushing
+
topology= [S390,EARLY]
Format: {off | on}
Specify if the kernel should make use of the cpu
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index a3df21d..a3caddd 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2664,3 +2664,13 @@ void __init arch_cpu_finalize_init(void)
*/
mem_encrypt_init();
}
+
+/* Control TLB flushing methods */
+static int __init tlbi_setup(char *str)
+{
+ if (!strcmp(str, "ipi"))
+ setup_clear_cpu_cap(X86_FEATURE_INVLPGB);
+
+ return 1;
+}
+__setup("tlbi=", tlbi_setup);