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authorKim Phillips <kim.phillips@amd.com>2022-02-28 11:23:15 -0600
committerBorislav Petkov <bp@suse.de>2022-02-28 18:37:08 +0100
commit244d00b5dd4755f8df892c86cab35fb2cfd4f14b (patch)
tree72eb087e1e58cc99734ce51e1fb022717eb3a129
parent44a3918c8245ab10c6c9719dd12e7a8d291980d8 (diff)
downloadlinux-244d00b5dd4755f8df892c86cab35fb2cfd4f14b.tar.bz2
x86/speculation: Use generic retpoline by default on AMD
AMD retpoline may be susceptible to speculation. The speculation execution window for an incorrect indirect branch prediction using LFENCE/JMP sequence may potentially be large enough to allow exploitation using Spectre V2. By default, don't use retpoline,lfence on AMD. Instead, use the generic retpoline. Signed-off-by: Kim Phillips <kim.phillips@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de>
-rw-r--r--arch/x86/kernel/cpu/bugs.c9
1 files changed, 0 insertions, 9 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 0a4267c63d3b..a36bfe2c2480 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -941,15 +941,6 @@ static enum spectre_v2_mitigation __init spectre_v2_select_retpoline(void)
return SPECTRE_V2_NONE;
}
- if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
- boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
- if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
- pr_err("LFENCE not serializing, switching to generic retpoline\n");
- return SPECTRE_V2_RETPOLINE;
- }
- return SPECTRE_V2_LFENCE;
- }
-
return SPECTRE_V2_RETPOLINE;
}