x86/bugs: Add X86_BUG_SPECTRE_V2_USER

All CPU vulnerabilities with command line options map to a single X86_BUG bit
except for Spectre V2 where both the spectre_v2 and spectre_v2_user command
line options are related to the same bug.

The spectre_v2 command line options mostly relate to user->kernel and
guest->host mitigations, while the spectre_v2_user command line options relate
to user->user or guest->guest protections.

Define a new X86_BUG bit for spectre_v2_user so each *_select_mitigation()
function in bugs.c is related to a unique X86_BUG bit.

No functional changes.

Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250108202515.385902-2-david.kaplan@amd.com

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index c8701abb77524b4ed2c67dbda5f3e985bcff8059..0bc420319ee248a7c4e8807682192e2f58d5aed3 100644 (file)
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -537,4 +537,5 @@
 #define X86_BUG_RFDS                   X86_BUG(1*32 + 2) /* "rfds" CPU is vulnerable to Register File Data Sampling */
 #define X86_BUG_BHI                    X86_BUG(1*32 + 3) /* "bhi" CPU is affected by Branch History Injection */
 #define X86_BUG_IBPB_NO_RET            X86_BUG(1*32 + 4) /* "ibpb_no_ret" IBPB omits return target predictions */
+#define X86_BUG_SPECTRE_V2_USER                X86_BUG(1*32 + 5) /* "spectre_v2_user" CPU is affected by Spectre variant 2 attack between user processes */
 #endif /* _ASM_X86_CPUFEATURES_H */

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 7cce91b19fb2c5bf59fb09dd392e6f79c8a55a14..1e80d76dc9c1d7a6874ef950aedc0957ace2068b 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1331,8 +1331,10 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 
        setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
 
-       if (!cpu_matches(cpu_vuln_whitelist, NO_SPECTRE_V2))
+       if (!cpu_matches(cpu_vuln_whitelist, NO_SPECTRE_V2)) {
                setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
+               setup_force_cpu_bug(X86_BUG_SPECTRE_V2_USER);
+       }
 
        if (!cpu_matches(cpu_vuln_whitelist, NO_SSB) &&
            !(x86_arch_cap_msr & ARCH_CAP_SSB_NO) &&