[v6] Attack vector controls (part 2)

[PATCH v6 19/21] x86/pti: Add attack vector controls for PTI

Posted by David Kaplan 2 months, 4 weeks ago

Disable PTI mitigation if user->kernel attack vector mitigations are
disabled.

Signed-off-by: David Kaplan <david.kaplan@amd.com>
---
 arch/x86/mm/pti.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index c0c40b67524e..b10d4d131dce 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -38,6 +38,7 @@
 #include <asm/desc.h>
 #include <asm/sections.h>
 #include <asm/set_memory.h>
+#include <asm/bugs.h>
 
 #undef pr_fmt
 #define pr_fmt(fmt)     "Kernel/User page tables isolation: " fmt
@@ -84,7 +85,8 @@ void __init pti_check_boottime_disable(void)
 		return;
 	}
 
-	if (cpu_mitigations_off())
+	if (pti_mode == PTI_AUTO &&
+	    !cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL))
 		pti_mode = PTI_FORCE_OFF;
 	if (pti_mode == PTI_FORCE_OFF) {
 		pti_print_if_insecure("disabled on command line.");
-- 
2.34.1

[tip: x86/bugs] x86/pti: Add attack vector controls for PTI

Posted by tip-bot2 for David Kaplan 2 months, 3 weeks ago

The following commit has been merged into the x86/bugs branch of tip:

Commit-ID:     02c7d5b8e0d123185817f533ed12622ed1c695e5
Gitweb:        https://git.kernel.org/tip/02c7d5b8e0d123185817f533ed12622ed1c695e5
Author:        David Kaplan <david.kaplan@amd.com>
AuthorDate:    Mon, 07 Jul 2025 13:33:14 -05:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Fri, 11 Jul 2025 17:56:41 +02:00

x86/pti: Add attack vector controls for PTI

Disable PTI mitigation if user->kernel attack vector mitigations are
disabled.

Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250707183316.1349127-20-david.kaplan@amd.com
---
 arch/x86/mm/pti.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 1902998..6dba18f 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -38,6 +38,7 @@
 #include <asm/desc.h>
 #include <asm/sections.h>
 #include <asm/set_memory.h>
+#include <asm/bugs.h>
 
 #undef pr_fmt
 #define pr_fmt(fmt)     "Kernel/User page tables isolation: " fmt
@@ -84,7 +85,8 @@ void __init pti_check_boottime_disable(void)
 		return;
 	}
 
-	if (cpu_mitigations_off())
+	if (pti_mode == PTI_AUTO &&
+	    !cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL))
 		pti_mode = PTI_FORCE_OFF;
 	if (pti_mode == PTI_FORCE_OFF) {
 		pti_print_if_insecure("disabled on command line.");