diff options
Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 18 |
1 files changed, 4 insertions, 14 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 992f832c447b..6383f0db098c 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -284,18 +284,6 @@ static const char * const spectre_v1_strings[] = { [SPECTRE_V1_MITIGATION_AUTO] = "Mitigation: usercopy/swapgs barriers and __user pointer sanitization", }; -static bool is_swapgs_serializing(void) -{ - /* - * Technically, swapgs isn't serializing on AMD (despite it previously - * being documented as such in the APM). But according to AMD, %gs is - * updated non-speculatively, and the issuing of %gs-relative memory - * operands will be blocked until the %gs update completes, which is - * good enough for our purposes. - */ - return boot_cpu_data.x86_vendor == X86_VENDOR_AMD; -} - /* * Does SMAP provide full mitigation against speculative kernel access to * userspace? @@ -346,9 +334,11 @@ static void __init spectre_v1_select_mitigation(void) * PTI as the CR3 write in the Meltdown mitigation * is serializing. * - * If neither is there, mitigate with an LFENCE. + * If neither is there, mitigate with an LFENCE to + * stop speculation through swapgs. */ - if (!is_swapgs_serializing() && !boot_cpu_has(X86_FEATURE_PTI)) + if (boot_cpu_has_bug(X86_BUG_SWAPGS) && + !boot_cpu_has(X86_FEATURE_PTI)) setup_force_cpu_cap(X86_FEATURE_FENCE_SWAPGS_USER); /* |