x86/speculation: Rename RETPOLINE_AMD to RETPOLINE_LFENCE

The RETPOLINE_AMD name is unfortunate since it isn't necessarily
AMD only, in fact Hygon also uses it. Furthermore it will likely be
sufficient for some Intel processors. Therefore rename the thing to
RETPOLINE_LFENCE to better describe what it is.

Add the spectre_v2=retpoline,lfence option as an alias to
spectre_v2=retpoline,amd to preserve existing setups. However, the output
of /sys/devices/system/cpu/vulnerabilities/spectre_v2 will be changed.

  [ bp: Fix typos, massage. ]

Co-developed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 6db4e29..65d1479 100644 (file)
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -204,7 +204,7 @@
 /* FREE!                                ( 7*32+10) */
 #define X86_FEATURE_PTI                        ( 7*32+11) /* Kernel Page Table Isolation enabled */
 #define X86_FEATURE_RETPOLINE          ( 7*32+12) /* "" Generic Retpoline mitigation for Spectre variant 2 */
-#define X86_FEATURE_RETPOLINE_AMD      ( 7*32+13) /* "" AMD Retpoline mitigation for Spectre variant 2 */
+#define X86_FEATURE_RETPOLINE_LFENCE   ( 7*32+13) /* "" Use LFENCE for Spectre variant 2 */
 #define X86_FEATURE_INTEL_PPIN         ( 7*32+14) /* Intel Processor Inventory Number */
 #define X86_FEATURE_CDP_L2             ( 7*32+15) /* Code and Data Prioritization L2 */
 #define X86_FEATURE_MSR_SPEC_CTRL      ( 7*32+16) /* "" MSR SPEC_CTRL is implemented */

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index cc74dc5..c91d97b 100644 (file)
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -84,7 +84,7 @@
 #ifdef CONFIG_RETPOLINE
        ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), \
                      __stringify(jmp __x86_indirect_thunk_\reg), X86_FEATURE_RETPOLINE, \
-                     __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), X86_FEATURE_RETPOLINE_AMD
+                     __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), X86_FEATURE_RETPOLINE_LFENCE
 #else
        jmp     *%\reg
 #endif
@@ -94,7 +94,7 @@
 #ifdef CONFIG_RETPOLINE
        ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; call *%\reg), \
                      __stringify(call __x86_indirect_thunk_\reg), X86_FEATURE_RETPOLINE, \
-                     __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; call *%\reg), X86_FEATURE_RETPOLINE_AMD
+                     __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; call *%\reg), X86_FEATURE_RETPOLINE_LFENCE
 #else
        call    *%\reg
 #endif
@@ -146,7 +146,7 @@ extern retpoline_thunk_t __x86_indirect_thunk_array[];
        "lfence;\n"                                             \
        ANNOTATE_RETPOLINE_SAFE                                 \
        "call *%[thunk_target]\n",                              \
-       X86_FEATURE_RETPOLINE_AMD)
+       X86_FEATURE_RETPOLINE_LFENCE)
 
 # define THUNK_TARGET(addr) [thunk_target] "r" (addr)
 
@@ -176,7 +176,7 @@ extern retpoline_thunk_t __x86_indirect_thunk_array[];
        "lfence;\n"                                             \
        ANNOTATE_RETPOLINE_SAFE                                 \
        "call *%[thunk_target]\n",                              \
-       X86_FEATURE_RETPOLINE_AMD)
+       X86_FEATURE_RETPOLINE_LFENCE)
 
 # define THUNK_TARGET(addr) [thunk_target] "rm" (addr)
 #endif
@@ -188,8 +188,8 @@ extern retpoline_thunk_t __x86_indirect_thunk_array[];
 /* The Spectre V2 mitigation variants */
 enum spectre_v2_mitigation {
        SPECTRE_V2_NONE,
-       SPECTRE_V2_RETPOLINE_GENERIC,
-       SPECTRE_V2_RETPOLINE_AMD,
+       SPECTRE_V2_RETPOLINE,
+       SPECTRE_V2_LFENCE,
        SPECTRE_V2_IBRS_ENHANCED,
 };
 

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 5007c3f..b4470ea 100644 (file)
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -389,7 +389,7 @@ static int emit_indirect(int op, int reg, u8 *bytes)
  *
  *   CALL *%\reg
  *
- * It also tries to inline spectre_v2=retpoline,amd when size permits.
+ * It also tries to inline spectre_v2=retpoline,lfence when size permits.
  */
 static int patch_retpoline(void *addr, struct insn *insn, u8 *bytes)
 {
@@ -407,7 +407,7 @@ static int patch_retpoline(void *addr, struct insn *insn, u8 *bytes)
        BUG_ON(reg == 4);
 
        if (cpu_feature_enabled(X86_FEATURE_RETPOLINE) &&
-           !cpu_feature_enabled(X86_FEATURE_RETPOLINE_AMD))
+           !cpu_feature_enabled(X86_FEATURE_RETPOLINE_LFENCE))
                return -1;
 
        op = insn->opcode.bytes[0];
@@ -438,9 +438,9 @@ static int patch_retpoline(void *addr, struct insn *insn, u8 *bytes)
        }
 
        /*
-        * For RETPOLINE_AMD: prepend the indirect CALL/JMP with an LFENCE.
+        * For RETPOLINE_LFENCE: prepend the indirect CALL/JMP with an LFENCE.
         */
-       if (cpu_feature_enabled(X86_FEATURE_RETPOLINE_AMD)) {
+       if (cpu_feature_enabled(X86_FEATURE_RETPOLINE_LFENCE)) {
                bytes[i++] = 0x0f;
                bytes[i++] = 0xae;
                bytes[i++] = 0xe8; /* LFENCE */

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 1c1f218..e3bb8af 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -664,7 +664,7 @@ enum spectre_v2_mitigation_cmd {
        SPECTRE_V2_CMD_FORCE,
        SPECTRE_V2_CMD_RETPOLINE,
        SPECTRE_V2_CMD_RETPOLINE_GENERIC,
-       SPECTRE_V2_CMD_RETPOLINE_AMD,
+       SPECTRE_V2_CMD_RETPOLINE_LFENCE,
 };
 
 enum spectre_v2_user_cmd {
@@ -824,8 +824,8 @@ set_mode:
 
 static const char * const spectre_v2_strings[] = {
        [SPECTRE_V2_NONE]                       = "Vulnerable",
-       [SPECTRE_V2_RETPOLINE_GENERIC]          = "Mitigation: Full generic retpoline",
-       [SPECTRE_V2_RETPOLINE_AMD]              = "Mitigation: Full AMD retpoline",
+       [SPECTRE_V2_RETPOLINE]                  = "Mitigation: Retpolines",
+       [SPECTRE_V2_LFENCE]                     = "Mitigation: LFENCE",
        [SPECTRE_V2_IBRS_ENHANCED]              = "Mitigation: Enhanced IBRS",
 };
 
@@ -837,7 +837,8 @@ static const struct {
        { "off",                SPECTRE_V2_CMD_NONE,              false },
        { "on",                 SPECTRE_V2_CMD_FORCE,             true  },
        { "retpoline",          SPECTRE_V2_CMD_RETPOLINE,         false },
-       { "retpoline,amd",      SPECTRE_V2_CMD_RETPOLINE_AMD,     false },
+       { "retpoline,amd",      SPECTRE_V2_CMD_RETPOLINE_LFENCE,  false },
+       { "retpoline,lfence",   SPECTRE_V2_CMD_RETPOLINE_LFENCE,  false },
        { "retpoline,generic",  SPECTRE_V2_CMD_RETPOLINE_GENERIC, false },
        { "auto",               SPECTRE_V2_CMD_AUTO,              false },
 };
@@ -875,13 +876,19 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
        }
 
        if ((cmd == SPECTRE_V2_CMD_RETPOLINE ||
-            cmd == SPECTRE_V2_CMD_RETPOLINE_AMD ||
+            cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE ||
             cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC) &&
            !IS_ENABLED(CONFIG_RETPOLINE)) {
                pr_err("%s selected but not compiled in. Switching to AUTO select\n", mitigation_options[i].option);
                return SPECTRE_V2_CMD_AUTO;
        }
 
+       if ((cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE) &&
+           !boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
+               pr_err("%s selected, but CPU doesn't have a serializing LFENCE. Switching to AUTO select\n", mitigation_options[i].option);
+               return SPECTRE_V2_CMD_AUTO;
+       }
+
        spec_v2_print_cond(mitigation_options[i].option,
                           mitigation_options[i].secure);
        return cmd;
@@ -916,9 +923,9 @@ static void __init spectre_v2_select_mitigation(void)
                if (IS_ENABLED(CONFIG_RETPOLINE))
                        goto retpoline_auto;
                break;
-       case SPECTRE_V2_CMD_RETPOLINE_AMD:
+       case SPECTRE_V2_CMD_RETPOLINE_LFENCE:
                if (IS_ENABLED(CONFIG_RETPOLINE))
-                       goto retpoline_amd;
+                       goto retpoline_lfence;
                break;
        case SPECTRE_V2_CMD_RETPOLINE_GENERIC:
                if (IS_ENABLED(CONFIG_RETPOLINE))
@@ -935,17 +942,17 @@ static void __init spectre_v2_select_mitigation(void)
 retpoline_auto:
        if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
            boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
-       retpoline_amd:
+       retpoline_lfence:
                if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
                        pr_err("Spectre mitigation: LFENCE not serializing, switching to generic retpoline\n");
                        goto retpoline_generic;
                }
-               mode = SPECTRE_V2_RETPOLINE_AMD;
-               setup_force_cpu_cap(X86_FEATURE_RETPOLINE_AMD);
+               mode = SPECTRE_V2_LFENCE;
+               setup_force_cpu_cap(X86_FEATURE_RETPOLINE_LFENCE);
                setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
        } else {
        retpoline_generic:
-               mode = SPECTRE_V2_RETPOLINE_GENERIC;
+               mode = SPECTRE_V2_RETPOLINE;
                setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
        }
 

diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index 89b3fb2..afbdda5 100644 (file)
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -34,7 +34,7 @@ SYM_INNER_LABEL(__x86_indirect_thunk_\reg, SYM_L_GLOBAL)
 
        ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), \
                      __stringify(RETPOLINE \reg), X86_FEATURE_RETPOLINE, \
-                     __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *%\reg; int3), X86_FEATURE_RETPOLINE_AMD
+                     __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *%\reg; int3), X86_FEATURE_RETPOLINE_LFENCE
 
 .endm
 

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 2b1e266..0ecb140 100644 (file)
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -394,7 +394,7 @@ static void emit_indirect_jump(u8 **pprog, int reg, u8 *ip)
        u8 *prog = *pprog;
 
 #ifdef CONFIG_RETPOLINE
-       if (cpu_feature_enabled(X86_FEATURE_RETPOLINE_AMD)) {
+       if (cpu_feature_enabled(X86_FEATURE_RETPOLINE_LFENCE)) {
                EMIT_LFENCE();
                EMIT2(0xFF, 0xE0 + reg);
        } else if (cpu_feature_enabled(X86_FEATURE_RETPOLINE)) {

diff --git a/tools/arch/x86/include/asm/cpufeatures.h b/tools/arch/x86/include/asm/cpufeatures.h
index 6db4e29..ab4e537 100644 (file)
--- a/tools/arch/x86/include/asm/cpufeatures.h
+++ b/tools/arch/x86/include/asm/cpufeatures.h
@@ -204,7 +204,7 @@
 /* FREE!                                ( 7*32+10) */
 #define X86_FEATURE_PTI                        ( 7*32+11) /* Kernel Page Table Isolation enabled */
 #define X86_FEATURE_RETPOLINE          ( 7*32+12) /* "" Generic Retpoline mitigation for Spectre variant 2 */
-#define X86_FEATURE_RETPOLINE_AMD      ( 7*32+13) /* "" AMD Retpoline mitigation for Spectre variant 2 */
+#define X86_FEATURE_RETPOLINE_LFENCE   ( 7*32+13) /* "" Use LFENCEs for Spectre variant 2 */
 #define X86_FEATURE_INTEL_PPIN         ( 7*32+14) /* Intel Processor Inventory Number */
 #define X86_FEATURE_CDP_L2             ( 7*32+15) /* Code and Data Prioritization L2 */
 #define X86_FEATURE_MSR_SPEC_CTRL      ( 7*32+16) /* "" MSR SPEC_CTRL is implemented */